5/1/08 - SAVE OUR EARTH

May 16, 2008

Indonesia may lose 2,000 islands to warming

Indonesia could lose about 2,000 islands by 2030 due to climate change, the country’s environment minister said on Monday.

“It is very, very serious,” Rachmat Witoelar said at a media conference attended by Yvo de Boer, executive secretary of the U.N. climate treaty secretariat.

He said studies by U.N. experts showed that sea levels were expected to rise about 89 centimeters, or 35 inches, in 2030 which meant that about 2,000 mostly uninhabited small islets would be submerged.

“We are still in a better position. Island countries like Saint Lucia, Fiji and the Bahamas would likely disappear,” he told Reuters.

Indonesia, which consists of 17,000 islands, has been trying to avert such a scenario by reducing reliance on fossil fuels and switching to biofuels, he said.

“We are optimistic it can be prevented. Switching to biofuels is not only good for the environment but also will benefit us economically considering the volatile state of oil prices,” he said.

Biofuels can be substituted for fossil fuels and are seen as a way to reduce the emission of greenhouse gases which are believed to contribute to global warming.

Rice shortages
The environment minister also said rice shortages are forecast for next year because of wild weather blamed on climate change. “It is feared there will be a lack of rice production next year because of the changes in the weather and because the farmers are not used to this,” he said.

A major U.N. conference on climate change will be held in the Indonesian island of Bali in December.

A draft U.N. report due to be released in Paris on Feb. 2 projects a big rise in temperatures this century and warns of more heat waves, floods, droughts and rising seas linked to greenhouse gases.

World leaders signed a U.N. Climate Convention in 1992 with an overriding goal of stabilizing greenhouse gases at levels preventing “dangerous (human) interference with the climate system”.

However, it did not define “dangerous” and the issue has been a vexed point in efforts to slow climate change ever since.

Under the Kyoto Protocol, the U.N. plan for fighting global warming, 35 industrial nations have agreed to cut emissions by 5 percent below 1990 levels by 2008-12.

President Bush pulled the United States out of the protocol in 2001, saying it would damage the U.S. economy and wrongly exempted developing nations from the first phase.

Source http://www.msnbc.msn.com/id/16867998/

Indonesia losing crops, fish stocks to global warming

Millions of fishermen are facing harsher weather conditions, while dwindling fish stocks affect their income.Indonesia is losing tonnes of crop production each year and its fish stock is dwindling as a result of global warming, a UN report said on Tuesday, putting the greatest pressure on the nation's poor. Millions of poor Indonesians will suffer loss of livelihoods, undermining the government's efforts to fight poverty, the report by the United Nations Development Programme (UNDP) said. The report was launched ahead of the UN climate change talks next week on the tourist island of Bali, where delegates from 189 countries will hammer out a replacement for the Kyoto Protocol, a pact against global warming which runs out in 2012. Shifting weather patterns have made it increasingly difficult for Indonesian farmers to decide when to plant their crops, and erratic droughts and rainfall have led to crop failures, the report said. The report quoted a study by a local research institute which said that Indonesia had lost 300,000 tonnes of crop production every year between 1992-2000, three times the annual loss in the previous decade. Indonesia's 40 million poor, including farmers and fishermen, will be the worst affected due to threats including rising sea levels, prolonged droughts and tropical cyclones, the report said. "No one can escape from climate change. But the effects will be felt more acutely by the poorest people, who are living in the most marginal areas that are vulnerable to drought, for example, or to floods and landslide," the report said. "Already one of the world's most disaster-prone countries, Indonesia faces increased exposure to droughts, floods and storms as well as disruption in agricultural production," the UNDP said in a press statement. Developed countries are responsible for the majority of greenhouse gas emissions which cause global warming, said UNDP's Country Director Hakan Bjorkman at the launch of the report. "The poor walk the earth with very light carbon footprint," Bjorkman said, but "they are set to suffer the most from the actions of a few."

Source http://www.alertnet.org/thenews/newsdesk/JAK84229.htm

Global Warming Effects Coral Reefs: Bali

Bali’s tourist pulling-power may be a thing of the past. In the West Bali National Park, the once common sight of vibrantly-coloured clown fish swimming among healthy pink anemones is becoming rare. And larger fish are increasingly uncommon.

Rising sea temperatures are aiding the bleaching process on coral reefs.

Experts say climate change is hitting Bali’s coral reefs hard, turning once vibrant diving locations into bleached shadows of their former glory.

While it struggles to recover from the effects of two terrorist bombings, Bali’s tourism industry has to face the problems of global warming.

Greenpeace activists in Bali’s busy Kuta district have staged a protest, urging greater action to tackle the problem of climate change.

The warming situation has been compounded by the widespread, but illegal, use of cyanide and explosive lures by local fishermen.

Despite a government ban, fishermen are using potassium cyanide to catch fish. They spray the highly toxic compound into holes in the coral to flush out the fish, which are then scooped up.

Sumber : http://www.planetmole.org/indonesian-news/global-warming-effects-coral-reefs-bali.html

5 Deadliest Effects of Global Warming

Green house gases stay can stay in the atmosphere for an amount of years ranging from decades to hundreds and thousands of years. No matter what we do, global warming is going to have some effect on Earth. Here are the 5 deadliest effects of global warming.

5. Spread of disease
As northern countries warm, disease carrying insects migrate north, bringing plague and disease with them. Indeed some scientists believe that in some countries thanks to global warming, malaria has not been fully eradicated.

Disease

4. Warmer waters and more hurricanes
As the temperature of oceans rises, so will the probability of more frequent and stronger hurricanes. We saw in this in 2004 and 2005.

hurricanes, an effect of global warming

3. Increased probability and intensity of droughts and heat waves
Although some areas of Earth will become wetter due to global warming, other areas will suffer serious droughts and heat waves. Africa will receive the worst of it, with more severe droughts also expected in Europe. Water is already a dangerously rare commodity in Africa, and according to the Intergovernmental Panel on Climate Change, global warming will exacerbate the conditions and could lead to conflicts and war.

Droughts are an effect of global warming

2. Economic consequences
Most of the effects of anthropogenic global warming won’t be good. And these effects spell one thing for the countries of the world: economic consequences. Hurricanes cause do billions of dollars in damage, diseases cost money to treat and control and conflicts exacerbate all of these.

Economic consequences of global warming

1. Polar ice caps melting
The ice caps melting is a four-pronged danger.

First, it will raise sea levels. There are 5,773,000 cubic miles of water in ice caps, glaciers, and permanent snow. According to the National Snow and Ice Data Center, if all glaciers melted today the seas would rise about 230 feet. Luckily, that’s not going to happen all in one go! But sea levels will rise.

Second, melting ice caps will throw the global ecosystem out of balance. The ice caps are fresh water, and when they melt they will desalinate the ocean, or in plain English - make it less salty. The desalinization of the gulf current will “screw up” ocean currents, which regulate temperatures. The stream shutdown or irregularity would cool the area around north-east America and Western Europe. Luckily, that will slow some of the other effects of global warming in that area!

Third, temperature rises and changing landscapes in the artic circle will endanger several species of animals. Only the most adaptable will survive.

Fourth, global warming could snowball with the ice caps gone. Ice caps are white, and reflect sunlight, much of which is relected back into space, further cooling Earth. If the ice caps melt, the only reflector is the ocean. Darker colors absorb sunlight, further warming the Earth.

Ice caps meting, the deadliest effect of global warming?

So what is the solution? Are we just being negative? Are there any positive effects of global warming? What about all the stupid global warming solutions. We welcome your thoughts.

Source http://www.environmentalgraffiti.com/sciencetech/5-deadliest-effects-of-global-warming/276

Pengaruh Pemanasan Global Bagi Indonesia

Perubahan pola cuaca yang terjadi belakangan telah mengakibatkan banyak hal. Hal itu tidak hanya memengaruhi pertanian yang bergantung pada musim, tapi juga menimbulkan berbagai jenis penyakit.

Perubahan cuaca tersebut hanya satu contoh dampak yang dilahirkan perubahan iklim global. Perubahan iklim global tidak hanya terjadi di Indonesia, namun hampir di semua belahan bumi. Tetapi, perubahan iklim itu juga disebabkan hal lain, yaitu pemanasan global (global warming).

Pemanasan global adalah kejadian meningkatnya temperatur rata-rata atmosfer, laut, dan daratan. Penyebabnya, pembakaran bahan bakar fosil, seperti batu bara, minyak bumi, dan gas alam. Pembakaran tersebut melepas karbondioksida (CO2), gas metan (CH4), nitrous oksida (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs ), dan sulphur hexafluoride (SF6) di atmosfer yang dikenal sebagai gas rumah kaca (GRK).

Bagaimana dampak yang dirasakan Indonesia? Tidak dapat dimungkiri, kebijakan pemerintah mengimpor beras pada akhir 2006 dan awal 2007 ini adalah sebagai salah satu akibat dari tidak menentunya cuaca akibat pemanasan global. Hal itu diakui Menteri Pertanian Anton Apriantono. "Mau bagaimana lagi. Kita kan tidak bisa memprediksi kapan datangnya hujan," ungkap Anton kepada Jawa Pos beberapa waktu lalu.

Kepala Badan Meteorologi dan Geofisika (BMG) Sri Woro B. Harijanto mengungkapkan, sebenarnya Indonesia telah merasakan efek global warming dalam tiga tahun terakhir. Dia mencontohkan terlambatnya musim penghujan yang seharusnya sudah turun pada Oktober lalu. Namun, hingga Desember, hujan tak kunjung datang. Keterlambatan itu juga disertai dengan pendeknya periode hujan, namun intensitasnya tinggi. "Akibatnya, kemarin banjir melanda Jakarta dan sekitarnya," ujar Woro.

Anomali itu, lanjut Woro, banyak pihak merasakan dampak negatifnya. "Terutama mereka yang mata pencahariannya bergantung pada cuaca, seperti petani dan nelayan," jelasnya.

Dia menambahkan, khusus untuk Indonesia, fenomena yang terjadi saat ini lebih disebabkan pada rumitnya posisi geografis. Pengaruh itu terbagi atas pengaruh global dan pengaruh lokal. Pengaruh global disebabkan posisi Indonesia terletak di sekitar Samudera Pasifik dan Lautan Hindia.

Sementara itu, pengaruh lokal disebabkan topografi Indonesia. Letak Indonesia pada garis ekuator juga membuat sirkulasi khas yang memengaruhi cuaca. "Maka, kita harus hati-hati ketika berbicara tentang cuaca atau musim," bebernya. Meski demikian, sesuai dengan tugasnya, BMG selalu melansir informasi yang terkait dengan cuaca tersebut untuk kepentingan maritim ataupun publik.

Pemanasan global akibat ulah manusia juga diakui Menteri Lingkungan Hidup Rachmat Witoelar. "Terpuruknya dunia ini akibat ulah manusia," ujar Rachmat. Karena itu, manusia juga harus mengobatinya. "Manusia harus berusaha mengatasinya," tambahnya.

Dulu, isu perubahan iklim belum ditanggapi serius oleh manusia. "Dulu hanya dianggap biasa saja. Padahal, ini berbeda dengan gempa misalnya," katanya.

Dampak dari perubahan iklim sangat membahayakan kehidupan. Bahkan, menurut Rahmat, ancaman yang ditimbulkan lebih berbahaya daripada terorisme. Sebab, dampaknya akan menyebabkan kerusakan fatal di bumi pada beberapa dekade ke depan. "Bukan (ancaman) global terrorism tidak penting, tapi ini (climate change) lebih penting," tukasnya.

Salah satu yang dimaksud dengan kerusakan fatal itu adalah ancaman bagi keanekaragaman hayati. Pasalnya, setiap spesies harus beradaptasi dengan perubahan iklim. Jika tidak, diperkirakan satu juta spesies akan punah.

Selain itu, di antara 17.500 pulau di Indonesia, sekitar 4.000 pulau akan tenggelam karena naiknya permukaan air laut ke daratan. Mengatasinya memang tidak mudah. Sebab, itu juga bergantung pada subjektivitas masing-masing negara dalam menyikapi perubahan iklim. "Tidak mudah karena perbedaan kepentingan antara negara maju dan negara berkembang. Mungkin saja Amerika bilang nggak apa-apa. Tetapi kita?" jelas mantan Dubes RI untuk Rusia tersebut. (joe)

Sumber: bbc

May 15, 2008

Pemanasan Global Tingkatkan Kasus Flu Burung

Pemanasan global mengakibatkan meningkatnya kasus flu burung (Avian Influenza/AI) karena meningkatnya suhu udara mendorong peningkatan penguapan sehingga kondisi udara lebih lembab, sementara virus AI sangat menyukai kondisi lembab dan dingin.Oleh karena itu, Badan Meteorologi dan Geofisika (BMG) akan mengupayakan agar efek pemanasan global terhadap peningkatan kasus AI ini bisa dimasukkan dalam pembahasan sidang UN Forum on Convention on Climate Change (UNFCCC) di Bali, Desember mendatang.Kepala Pusat Penelitian dan Pengembangan BMG, Prof Mezak A Ratag mengatakan di Bogor, Senin, masalah tersebut --efek pemanasan global terhadap peningkatan kasus AI-- memang belum dikaji oleh Panel Antar-pemerintah untuk Perubahan Cuaca (Intergovernmental Panel on Climate Change)."Masalah ini belum masuk `assessment` perubahan iklim UNFCCC," katanya.

BMG, kata dia, akan melakukan pemetaan iklim (mikro klimat) di tingkat sub kabupaten sehingga bisa digunakan sebagai sistem peringatan dini bagi penyebaran virus flu burung."Kalau tadinya BMG hanya fokus (pemetaan iklim) untuk masalah pangan, sekarang juga ke masalah penyebaran penyakit," katanya.Sementara itu, peneliti dari Fakultas Kedokteran Hewan (FKH) Institut Pertanian Bogor (IPB), Agik Suprayogi mengatakan, angka kejadian AI di daerah tropis tinggi karena wilayah ini kelembabannya juga tinggi."Ada hubungan antara karakter klimat (mikro klimat) dengan kasus kejadian AI," katanya.Riset yang dilakukannya sejak 2003 tersebut mengambil sampel Bogor dan masih harus dipertajam lagi untuk skala nasional.Menurut hasil riset Agik, Bogor merupakan salah satu daerah potensial terjadi wabah flu burung karena karakter klimat di Bogor cenderung mengarah ke temperatur hangat, curah hujan tinggi dan sangat lembab.

Kemungkinan kondisi ini sangat disenangi oleh virus flu burung.Pada Desember 2004 sampai Februari 2005 terjadi wabah flu burung di Bogor karena bulan-bulan tersebut merupakan bulan yang lembab dengan temperatur udara rendah.Dengan adanya gambaran mengenai hubungan antara perubahan cuaca dan kejadian penyakit, maka dapat diperoleh metode untuk sistem peringatan dini bagi masyarakat."Seperti juga halnya untuk demam berdarah, masyarakat sudah tahu pada waktu-waktu kapan saja kita mesti ekstra hati-hati mengantisipasi penyebaran penyakit," katanya.

Sumber http://kkpjayapura.blogspot.com

May 14, 2008

Dampak pemanasan global

PADA PENGARUH CUACA.

Gunung-gunung es akan mencair
Daratan akan mengecil
Akan lebih sedikit es yang terapung di perairan sebelah utara
Daerah-daerah yang sebelumnya mengalami sealju ringan, tidak akan mengalaminya lagi
Di daerah subtropis, bagian pegunungan yang ditutupi salju akan semakin sedikit serta salju akan lebih cepat mencair
Musim tanam akan menjadi lebih panjang di beberapa area
Temperatur pada musim dingin dan malam hari akan cenderung meningkat
Daerah tropus akan menjadi lembap karena lebih banyak air yang menguap dari lautan

Kelembapan yang tinggi akan berdampak antara lain;

Curah hujan meningkat
Badai akan lebih sering terjadi
Air tanah akan cepat menguap
Beberapa daerah menjadi kering sebelumnya
Angin bertiup kencang dengan pola-pola yang berbeda
Terjadinya badai topan akan semakin besar
Beberapa periode yang sangat dingin akan terjadi
Pola cuaca menjadi tidak terprediksi dan lebih ekstrim

PADA PENGARUH KESEHATAN MANUSIA

Seperti demam berdarah dengue (DBD) dan malaria. Penyakit tersebut dipengaruhi curah hujan dan jumlah air hujan. Semakin tinggi curah hujan, semakin tinggi kasus DBD.
Lebih banyak orang terkena meninggal bahkan meninggal karena stres panas.
Meningkatnya insiden alergi dan penyakit pernapasan, karena udara yang lebih hangat akan memperbanyak polutan, spora mold, dan serbuk sari.
Meningkatnya penyakit-penyakit tropis lainnya seperti demam kuning dan enchepalitis

Sumber http://gogreenindonesia.blogspot.com

Pengaruh Pemanasan Global di Candi Borobudur

Tahun ini, Balai Konservasi Peninggalan Candi Borobudur akan mulai meneliti pengaruh pemanasan global terhadap batuan Candi Borobudur. Saat ini, upaya tersebut sudah diawali dengan mengumpulkan berbagai data diantaranya menyangkut kelembapan, suhu, dan cur ah hujan, selama 20 tahun terakhir.

"Namun, untuk melakukan analisis terhadap batuan candi, kami nantinya akan menggandeng ahli atau pakar dari pihak luar," ujar Kepala Balai Konservasi Peninggalan Borobudur, Marsis Sutopo, Kamis (10/4). Pihak luar yang akan dilibatkan adalah dosen, pakar klimatologi dari Universitas Gajah Mada (UGM) Yogyakarta.

Penelitian ini dimungkinkan akan berlangsung lama, lebih dari setahun. Dari kegiatan ini, nantinya akan diketahui seberapa besar pengaruh perubahan iklim dan cuaca terhadap sifat-sifat dan kondisi batuan candi.

Sumber http://www.kompas.com

Pengaruh Pemanasan Global Bagi Indonesia

Persetujuan internasional

Kerjasama internasional diperlukan untuk mensukseskan pengurangan gas-gas rumah kaca. Di tahun 1992, pada Earth Summit di Rio de Janeiro, Brazil, 150 negara berikrar untuk menghadapi masalah gas rumah kaca dan setuju untuk menterjemahkan maksud ini dalam suatu perjanjian yang mengikat. Pada tahun 1997 di Jepang, 160 negara merumuskan persetujuan yang lebih kuat yang dikenal dengan Protokol Kyoto.

Perjanjian ini, yang belum diimplementasikan, menyerukan kepada 38 negara-negara industri yang memegang persentase paling besar dalam melepaskan gas-gas rumah kaca untuk memotong emisi mereka ke tingkat 5 persen di bawah emisi tahun 1990. Pengurangan ini harus dapat dicapai paling lambat tahun 2012. Pada mulanya, Amerika Serikat mengajukan diri untuk melakukan pemotongan yang lebih ambisius, menjanjikan pengurangan emisi hingga 7 persen di bawah tingkat 1990; Uni Eropa, yang menginginkan perjanjian yang lebih keras, berkomitmen 8 persen; dan Jepang 6 persen. Sisa 122 negara lainnya, sebagian besar negara berkembang, tidak diminta untuk berkomitmen dalam pengurangan emisi gas.

Akan tetapi, pada tahun 2001, Presiden Amerika Serikat yang baru terpilih, George W. Bush mengumumkan bahwa perjanjian untuk pengurangan karbon dioksida tersebut menelan biaya yang sangat besar. Ia juga menyangkal dengan menyatakan bahwa negara-negara berkembang tidak dibebani dengan persyaratan pengurangan karbon dioksida ini. Kyoto Protokol tidak berpengaruh apa-apa bila negara-negara industri yang bertanggung jawab menyumbang 55 persen dari emisi gas rumah kaca pada tahun 1990 tidak meratifikasinya. Persyaratan itu berhasil dipenuhi ketika tahun 2004, Presiden Rusia Vladimir Putin meratifikasi perjanjian ini, memberikan jalan untuk berlakunya perjanjian ini mulai 16 Februari 2005.

Banyak orang mengkritik Protokol Kyoto terlalu lemah. Bahkan jika perjanjian ini dilaksanakan segera, ia hanya akan sedikit mengurangi bertambahnya konsentrasi gas-gas rumah kaca di atmosfer. Suatu tindakan yang keras akan diperlukan nanti, terutama karena negara-negara berkembang yang dikecualikan dari perjanjian ini akan menghasilkan separuh dari emisi gas rumah kaca pada 2035. Penentang protokol ini memiliki posisi yang sangat kuat. Penolakan terhadap perjanjian ini di Amerika Serikat terutama dikemukakan oleh industri minyak, industri batubara dan perusahaan-perusahaan lainnya yang produksinya tergantung pada bahan bakar fosil. Para penentang ini mengklaim bahwa biaya ekonomi yang diperlukan untuk melaksanakan Protokol Kyoto dapat menjapai 300 milyar dollar AS, terutama disebabkan oleh biaya energi. Sebaliknya pendukung Protokol Kyoto percaya bahwa biaya yang diperlukan hanya sebesar 88 milyar dollar AS dan dapat lebih kurang lagi serta dikembalikan dalam bentuk penghematan uang setelah mengubah ke peralatan, kendaraan, dan proses industri yang lebih effisien.

Pada suatu negara dengan kebijakan lingkungan yang ketat, ekonominya dapat terus tumbuh walaupun berbagai macam polusi telah dikurangi. Akan tetapi membatasi emisi karbon dioksida terbukti sulit dilakukan. Sebagai contoh, Belanda, negara industrialis besar yang juga pelopor lingkungan, telah berhasil mengatasi berbagai macam polusi tetapi gagal untuk memenuhi targetnya dalam mengurangi produksi karbon dioksida.

Setelah tahun 1997, para perwakilan dari penandatangan Protokol Kyoto bertemu secara reguler untuk menegoisasikan isu-isu yang belum terselesaikan seperti peraturan, metode dan pinalti yang wajib diterapkan pada setiap negara untuk memperlambat emisi gas rumah kaca. Para negoisator merancang sistem di mana suatu negara yang memiliki program pembersihan yang sukses dapat mengambil keuntungan dengan menjual hak polusi yang tidak digunakan ke negara lain. Sistem ini disebut perdagangan karbon. Sebagai contoh, negara yang sulit meningkatkan lagi hasilnya, seperti Belanda, dapat membeli kredit polusi di pasar, yang dapat diperoleh dengan biaya yang lebih rendah. Rusia, merupakan negara yang memperoleh keuntungan bila sistem ini diterapkan. Pada tahun 1990, ekonomi Rusia sangat payah dan emisi gas rumah kacanya sangat tinggi. Karena kemudian Rusia berhasil memotong emisinya lebih dari 5 persen di bawah tingkat 1990, ia berada dalam posisi untuk menjual kredit emisi ke negara-negara industri lainnya, terutama mereka yang ada di Uni Eropa.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Menghilangkan karbon

Cara yang paling mudah untuk menghilangkan karbon dioksida di udara adalah dengan memelihara pepohonan dan menanam pohon lebih banyak lagi. Pohon, terutama yang muda dan cepat pertumbuhannya, menyerap karbon dioksida yang sangat banyak, memecahnya melalui fotosintesis, dan menyimpan karbon dalam kayunya. Di seluruh dunia, tingkat perambahan hutan telah mencapai level yang mengkhawatirkan. Di banyak area, tanaman yang tumbuh kembali sedikit sekali karena tanah kehilangan kesuburannya ketika diubah untuk kegunaan yang lain, seperti untuk lahan pertanian atau pembangunan rumah tinggal. Langkah untuk mengatasi hal ini adalah dengan penghutanan kembali yang berperan dalam mengurangi semakin bertambahnya gas rumah kaca.

Gas karbon dioksida juga dapat dihilangkan secara langsung. Caranya dengan menyuntikkan (menginjeksikan) gas tersebut ke sumur-sumur minyak untuk mendorong agar minyak bumi keluar ke permukaan (lihat Enhanced Oil Recovery). Injeksi juga bisa dilakukan untuk mengisolasi gas ini di bawah tanah seperti dalam sumur minyak, lapisan batubara atau aquifer. Hal ini telah dilakukan di salah satu anjungan pengeboran lepas pantai Norwegia, di mana karbon dioksida yang terbawa ke permukaan bersama gas alam ditangkap dan diinjeksikan kembali ke aquifer sehingga tidak dapat kembali ke permukaan.

Salah satu sumber penyumbang karbon dioksida adalah pembakaran bahan bakar fosil. Penggunaan bahan bakar fosil mulai meningkat pesat sejak revolusi industri pada abad ke-18. Pada saat itu, batubara menjadi sumber energi dominan untuk kemudian digantikan oleh minyak bumi pada pertengahan abad ke-19. Pada abad ke-20, energi gas mulai biasa digunakan di dunia sebagai sumber energi. Perubahan tren penggunaan bahan bakar fosil ini sebenarnya secara tidak langsung telah mengurangi jumlah karbon dioksida yang dilepas ke udara, karena gas melepaskan karbon dioksida lebih sedikit bila dibandingkan dengan minyak apalagi bila dibandingkan dengan batubara. Walaupun demikian, penggunaan energi terbaharui dan energi nuklir lebih mengurangi pelepasan karbon dioksida ke udara. Energi nuklir, walaupun kontroversial karena alasan keselamatan dan limbahnya yang berbahaya, bahkan tidak melepas karbon dioksida sama sekali.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Pengendalian PemanasanGlobal

Konsumsi total bahan bakar fosil di dunia meningkat sebesar 1 persen per-tahun. Langkah-langkah yang dilakukan atau yang sedang diskusikan saat ini tidak ada yang dapat mencegah pemanasan global di masa depan. Tantangan yang ada saat ini adalah mengatasi efek yang timbul sambil melakukan langkah-langkah untuk mencegah semakin berubahnya iklim di masa depan.

Kerusakan yang parah dapat diatasi dengan berbagai cara. Daerah pantai dapat dilindungi dengan dinding dan penghalang untuk mencegah masuknya air laut. Cara lainnya, pemerintah dapat membantu populasi di pantai untuk pindah ke daerah yang lebih tinggi. Beberapa negara, seperti Amerika Serikat, dapat menyelamatkan tumbuhan dan hewan dengan tetap menjaga koridor (jalur) habitatnya, mengosongkan tanah yang belum dibangun dari selatan ke utara. Spesies-spesies dapat secara perlahan-lahan berpindah sepanjang koridor ini untuk menuju ke habitat yang lebih dingin.

Ada dua pendekatan utama untuk memperlambat semakin bertambahnya gas rumah kaca. Pertama, mencegah karbon dioksida dilepas ke atmosfer dengan menyimpan gas tersebut atau komponen karbon-nya di tempat lain. Cara ini disebut carbon sequestration (menghilangkan karbon). Kedua, mengurangi produksi gas rumah kaca.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Pertanian, Kesehatan Manusia, Hewan dan Tumbuhan

Orang mungkin beranggapan bahwa Bumi yang hangat akan menghasilkan lebih banyak makanan dari sebelumnya, tetapi hal ini sebenarnya tidak sama di beberapa tempat. Bagian Selatan Kanada, sebagai contoh, mungkin akan mendapat keuntungan dari lebih tingginya curah hujan dan lebih lamanya masa tanam. Di lain pihak, lahan pertanian tropis semi kering di beberapa bagian Afrika mungkin tidak dapat tumbuh. Daerah pertanian gurun yang menggunakan air irigasi dari gunung-gunung yang jauh dapat menderita jika snowpack (kumpulan salju) musim dingin, yang berfungsi sebagai reservoir alami, akan mencair sebelum puncak bulan-bulan masa tanam. Tanaman pangan dan hutan dapat mengalami serangan serangga dan penyakit yang lebih hebat.

Di dunia yang hangat, para ilmuan memprediksi bahwa lebih banyak orang yang terkena penyakit atau meninggal karena stress panas. Wabah penyakit yang biasa ditemukan di daerah tropis, seperti penyakit yang diakibatkan nyamuk dan hewan pembawa penyakit lainnya, akan semakin meluas karena mereka dapat berpindah ke daerah yang sebelumnya terlalu dingin bagi mereka. Saat ini, 45 persen penduduk dunia tinggal di daerah di mana mereka dapat tergigit oleh nyamuk pembawa parasit malaria; persentase itu akan meningkat menjadi 60 persen jika temperature meningkat. Penyakit-penyakit tropis lainnya juga dapat menyebar seperti malaria, seperti demam dengue, demam kuning, dan encephalitis. Para ilmuan juga memprediksi meningkatnya insiden alergi dan penyakit pernafasan karena udara yang lebih hangat akan memperbanyak polutan, spora mold dan serbuk sari.

Hewan dan tumbuhan menjadi makhluk hidup yang sulit menghindar dari efek pemanasan ini karena sebagian besar lahan telah dikuasai manusia. Dalam pemanasan global, hewan cenderung untuk bermigrasi ke arah kutub atau ke atas pegunungan. Tumbuhan akan mengubah arah pertumbuhannya, mencari daerah baru karena habitat lamanya menjadi terlalu hangat. Akan tetapi, pembangunan manusia akan menghalangi perpindahan ini. Spesies-spesies yang bermigrasi ke utara atau selatan yang terhalangi oleh kota-kota atau lahan-lahan pertanian mungkin akan mati. Beberapa tipe spesies yang tidak mampu secara cepat berpindah menuju kutub mungkin juga akan musnah.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Tinggi muka laut

Perubahan tinggi rata-rata muka laut diukur dari daerah dengan lingkungan yang stabil secara geologi.

Ketika atmosfer menghangat, lapisan permukaan lautan juga akan menghangat, sehingga volumenya akan membesar dan menaikkan tinggi permukaan laut. Pemanasan juga akan mencairkan banyak es di kutub, terutama sekitar Greenland, yang lebih memperbanyak volume air di laut. Tinggi muka laut di seluruh dunia telah meningkat 10 - 25 cm (4 - 10 inchi) selama abad ke-20, dan para ilmuan IPCC memprediksi peningkatan lebih lanjut 9 - 88 cm (4 - 35 inchi) pada abad ke-21.

Perubahan tinggi muka laut akan sangat mempengaruhi kehidupan di daerah pantai. Kenaikan 100 cm (40 inchi) akan menenggelamkan 6 persen daerah Belanda, 17,5 persen daerah Bangladesh, dan banyak pulau-pulau. Erosi dari tebing, pantai, dan bukit pasir akan meningkat. Ketika tinggi lautan mencapai muara sungai, banjir akibat air pasang akan meningkat di daratan. Negara-negara kaya akan menghabiskan dana yang sangat besar untuk melindungi daerah pantainya, sedangkan negara-negara miskin mungkin hanya dapat melakukan evakuasi dari daerah pantai.

Bahkan sedikit kenaikan tinggi muka laut akan sangat mempengaruhi ekosistem pantai. Kenaikan 50 cm (20 inchi) akan menenggelamkan separuh dari rawa-rawa pantai di Amerika Serikat. Rawa-rawa baru juga akan terbentuk, tetapi tidak di area perkotaan dan daerah yang sudah dibangun. Kenaikan muka laut ini akan menutupi sebagian besar dari Florida Everglades.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Cuaca

Para ilmuan memperkirakan bahwa selama pemanasan global, daerah bagian Utara dari belahan Bumi Utara (Northern Hemisphere) akan memanas lebih dari daerah-daerah lain di Bumi. Akibatnya, gunung-gunung es akan mencair dan daratan akan mengecil. Akan lebih sedikit es yang terapung di perairan Utara tersebut. Daerah-daerah yang sebelumnya mengalami salju ringan, mungkin tidak akan mengalaminya lagi. Pada pegunungan di daerah subtropis, bagian yang ditutupi salju akan semakin sedikit serta akan lebih cepat mencair. Musim tanam akan lebih panjang di beberapa area. Temperatur pada musim dingin dan malam hari akan cenderung untuk meningkat.

Daerah hangat akan menjadi lebih lembab karena lebih banyak air yang menguap dari lautan. Para ilmuan belum begitu yakin apakah kelembaban tersebut malah akan meningkatkan atau menurunkan pemanasan yang lebih jauh lagi. Hal ini disebabkan karena uap air merupakan gas rumah kaca, sehingga keberadaannya akan meningkatkan efek insulasi pada atmosfer. Akan tetapi, uap air yang lebih banyak juga akan membentuk awan yang lebih banyak, sehingga akan memantulkan cahaya matahari kembali ke angkasa luar, di mana hal ini akan menurunkan proses pemanasan (lihat siklus air). Kelembaban yang tinggi akan meningkatkan curah hujan, secara rata-rata, sekitar 1 persen untuk setiap derajat Fahrenheit pemanasan. (Curah hujan di seluruh dunia telah meningkat sebesar 1 persen dalam seratus tahun terakhir ini)^[22]. Badai akan menjadi lebih sering. Selain itu, air akan lebih cepat menguap dari tanah. Akibatnya beberapa daerah akan menjadi lebih kering dari sebelumnya. Angin akan bertiup lebih kencang dan mungkin dengan pola yang berbeda. Topan badai (hurricane) yang memperoleh kekuatannya dari penguapan air, akan menjadi lebih besar. Berlawanan dengan pemanasan yang terjadi, beberapa periode yang sangat dingin mungkin akan terjadi. Pola cuaca menjadi tidak terprediksi dan lebih ekstrim.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Model iklim

Prakiraan peningkatan temperature terhadap beberapa skenario kestabilan (pita berwarna) berdasarkan Laporan Pandangan IPCC ke Empat. Garis hitam menunjukkan prakiraan terbaik; garis merah dan biru menunjukkan batas-batas kemungkinan yang dapat terjadi.

Perhitungan pemanasan global pada tahun 2001 dari beberapa model iklim berdasarkan scenario SRES A2, yang mengasumsikan tidak ada tindakan yang dilakukan untuk mengurangi emisi.

Para ilmuan telah mempelajari pemanasan global berdasarkan model-model computer berdasarkan prinsip-prinsip dasar dinamikan fluida, transfer radiasi, dan proses-proses lainya, dengan beberapa penyederhanaan disebabkan keterbatasan kemampuan komputer. Model-model ini memprediksikan bahwa penambahan gas-gas rumah kaca berefek pada iklim yang lebih hangat.^[16] Walaupun digunakan asumsi-asumsi yang sama terhadap konsentrasi gas rumah kaca di masa depan, sensitivitas iklimnya masih akan berada pada suatu rentang tertentu.

Dengan memasukkan unsur-unsur ketidakpastian terhadap konsentrasi gas rumah kaca dan pemodelan iklim, IPCC memperkirakan pemanasan sekitar 1.1 °C hingga 6.4 °C (2.0 °F hingga 11.5 °F) antara tahun 1990 dan 2100.^[1] Model-model iklim juga digunakan untuk menyelidiki penyebab-penyebab perubahan iklim yang terjadi saat ini dengan membandingkan perubahan yang teramati dengan hasil prediksi model terhadap berbagai penyebab, baik alami maupun aktivitas manusia.

Model iklim saat ini menghasilkan kemiripan yang cukup baik dengan perubahan temperature global hasil pengamatan selama seratus tahun terakhir, tetapi tidak mensimulasi semua aspek dari iklim.^[17] Model-model ini tidak secara pasti menyatakan bahwa pemanasan yang terjadi antara tahun 1910 hingga 1945 disebabkan oleh proses alami atau aktivitas manusia; akan tetapi; mereka menunjukkan bahwa pemanasan sejak tahun 1975 didominasi oleh emisi gas-gas yang dihasilkan manusia.

Sebagian besar model-model iklim, ketika menghitung iklim di masa depan, dilakukan berdasarkan skenario-skenario gas rumah kaca, biasanya dari Laporan Khusus terhadap Skenario Emisi (Special Report on Emissions Scenarios / SRES) IPCC. Yang jarang dilakukan, model menghitung dengan menambahkan simulasi terhadap siklus karbon; yang biasanya menghasilkan umpan balik yang positif, walaupun responnya masih belum pasti (untuk skenario A2 SRES, respon bervariasi antara penambahan 20 dan 200 ppm CO₂). Beberapa studi-studi juga menunjukkan beberapa umpan balik positif.^[18]^[19]^[20]

Pengaruh awan juga merupakan salah satu sumber yang menimbulkan ketidakpastian terhadap model-model yang dihasilkan saat ini, walaupun sekarang telah ada kemajuan dalam menyelesaikan masalah ini. ^[21] Saat ini juga terjadi diskusi-diskusi yang masih berlanjut mengenai apakah model-model iklim mengesampingkan efek-efek umpan balik dan tak langsung dari variasi Matahari.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Mengukur pemanasan global

Hasil pengukuran konsentrasi CO₂ di Mauna Loa

Pada awal 1896, para ilmuan beranggapan bahwa membakar bahan bakar fosil akan mengubah komposisi atmosfer dan dapat meningkatkan temperatur rata-rata global. Hipotesis ini dikonfirmasi tahun 1957 ketika para peneliti yang bekerja pada program penelitian global yaitu International Geophysical Year, mengambil sampel atmosfer dari puncak gunung Mauna Loa di Hawai. Hasil pengukurannya menunjukkan terjadi peningkatan konsentrasi karbon dioksida di atmosfer. Setelah itu, komposisi dari atmosfer terus diukur dengan cermat. Data-data yang dikumpulkan menunjukkan bahwa memang terjadi peningkatan konsentrasi dari gas-gas rumah kaca di atmosfer.

Para ilmuan juga telah lama menduga bahwa iklim global semakin menghangat, tetapi mereka tidak mampu memberikan bukti-bukti yang tepat. Temperatur terus bervariasi dari waktu ke waktu dan dari lokasi yang satu ke lokasi lainnya. Perlu bertahun-tahun pengamatan iklim untuk memperoleh data-data yang menunjukkan suatu kecenderungan (trend) yang jelas. Catatan pada akhir 1980-an agak memperlihatkan kecenderungan penghangatan ini, akan tetapi data statistik ini hanya sedikit dan tidak dapat dipercaya. Stasiun cuaca pada awalnya, terletak dekat dengan daerah perkotaan sehingga pengukuran temperatur akan dipengaruhi oleh panas yang dipancarkan oleh bangunan dan kendaraan dan juga panas yang disimpan oleh material bangunan dan jalan. Sejak 1957, data-data diperoleh dari stasiun cuaca yang terpercaya (terletak jauh dari perkotaan), serta dari satelit. Data-data ini memberikan pengukuran yang lebih akurat, terutama pada 70 persen permukaan planet yang tertutup lautan. Data-data yang lebih akurat ini menunjukkan bahwa kecenderungan menghangatnya permukaan Bumi benar-benar terjadi. Jika dilihat pada akhir abad ke-20, tercatat bahwa sepuluh tahun terhangat selama seratus tahun terakhir terjadi setelah tahun 1980, dan tiga tahun terpanas terjadi setelah tahun 1990, dengan 1998 menjadi yang paling panas.

Dalam laporan yang dikeluarkannya tahun 2001, Intergovernmental Panel on Climate Change (IPCC) menyimpulkan bahwa temperatur udara global telah meningkat 0,6 derajat Celsius (1 derajat Fahrenheit) sejak 1861. Panel setuju bahwa pemanasan tersebut terutama disebabkan oleh aktifitas manusia yang menambah gas-gas rumah kaca ke atmosfer. IPCC memprediksi peningkatan temperatur rata-rata global akan meningkat 1.1 hingga 6.4 °C (2.0 hingga 11.5 °F) antara tahun 1990 dan 2100.

IPCC panel juga memperingatkan, bahwa meskipun konsentrasi gas di atmosfer tidak bertambah lagi sejak tahun 2100, iklim tetap terus menghangat selama periode tertentu akibat emisi yang telah dilepaskan sebelumnya. karbon dioksida akan tetap berada di atmosfer selama seratus tahun atau lebih sebelum alam mampu menyerapnya kembali. Jika emisi gas rumah kaca terus meningkat, para ahli memprediksi, konsentrasi karbondioksioda di atmosfer dapat meningkat hingga tiga kali lipat pada awal abad ke-22 bila dibandingkan masa sebelum era industri. Akibatnya, akan terjadi perubahan iklim secara dramatis. Walaupun sebenarnya peristiwa perubahan iklim ini telah terjadi beberapa kali sepanjang sejarah Bumi, manusia akan menghadapi masalah ini dengan resiko populasi yang sangat besar.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Variasi Matahari

Terdapat hipotesa yang menyatakan bahwa variasi dari Matahari, dengan kemungkinan diperkuat oleh umpan balik dari awan, dapat memberi kontribusi dalam pemanasan saat ini.[7] Perbedaan antara mekanisme ini dengan pemanasan akibat efek rumah kaca adalah meningkatnya aktivitas Matahari akan memanaskan stratosfer sebaliknya efek rumah kaca akan mendinginkan stratosfer. Pendinginan stratosfer bagian bawah paling tidak telah diamati sejak tahun 1960,[8] yang tidak akan terjadi bila aktivitas Matahari menjadi kontributor utama pemanasan saat ini. (Penipisan lapisan ozon juga dapat memberikan efek pendinginan tersebut tetapi penipisan tersebut terjadi mulai akhir tahun 1970-an.) Fenomena variasi Matahari dikombinasikan dengan aktivitas gunung berapi mungkin telah memberikan efek pemanasan dari masa pra-industri hingga tahun 1950, serta efek pendinginan sejak tahun 1950.[9][10]
Ada beberapa hasil penelitian yang menyatakan bahwa kontribusi Matahari mungkin telah diabaikan dalam pemanasan global. Dua ilmuan dari Duke University mengestimasikan bahwa Matahari mungkin telah berkontribusi terhadap 45-50% peningkatan temperatur rata-rata global selama periode 1900-2000, dan sekitar 25-35% antara tahun 1980 dan 2000.[11] Stott dan rekannya mengemukakan bahwa model iklim yang dijadikan pedoman saat ini membuat estimasi berlebihan terhadap efek gas-gas rumah kaca dibandingkan dengan pengaruh Matahari; mereka juga mengemukakan bahwa efek pendinginan dari debu vulkanik dan aerosol sulfat juga telah dipandang remeh.[12] Walaupun demikian, mereka menyimpulkan bahwa bahkan dengan meningkatkan sensitivitas iklim terhadap pengaruh Matahari sekalipun, sebagian besar pemanasan yang terjadi pada dekade-dekade terakhir ini disebabkan oleh gas-gas rumah kaca.
Pada tahun 2006, sebuah tim ilmuan dari Amerika Serikat, Jerman dan Swiss menyatakan bahwa mereka tidak menemukan adanya peningkatan tingkat "keterangan" dari Matahari pada seribu tahun terakhir ini. Siklus Matahari hanya memberi peningkatan kecil sekitar 0,07% dalam tingkat "keterangannya" selama 30 tahun terakhir. Efek ini terlalu kecil untuk berkontribusi terhadap pemansan global.[13][14] Sebuah penelitian oleh Lockwood dan Fröhlich menemukan bahwa tidak ada hubungan antara pemanasan global dengan variasi Matahari sejak tahun 1985, baik melalui variasi dari output Matahari maupun variasi dalam sinar kosmis.[15]

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Efek umpan balik

Efek-efek dari agen penyebab pemanasan global juga dipengaruhi oleh berbagai proses umpan balik yang dihasilkannya. Sebagai contoh adalah pada penguapan air. Pada kasus pemanasan akibat bertambahnya gas-gas rumah kaca seperti CO2, pemanasan pada awalnya akan menyebabkan lebih banyaknya air yang menguap ke atmosfer. Karena uap air sendiri merupakan gas rumah kaca, pemanasan akan terus berlanjut dan menambah jumlah uap air di udara hingga tercapainya suatu kesetimbangan konsentrasi uap air. Efek rumah kaca yang dihasilkannya lebih besar bila dibandingkan oleh akibat gas CO2 sendiri. (Walaupun umpan balik ini meningkatkan kandungan air absolut di udara, kelembaban relatif udara hampir konstan atau bahkan agak menurun karena udara menjadi menghangat).[4] Umpan balik ini hanya dapat dibalikkan secara perlahan-lahan karena CO2 memiliki usia yang panjang di atmosfer.
Efek-efek umpan balik karena pengaruh awan sedang menjadi objek penelitian saat ini. Bila dilihat dari bawah, awan akan memantulkan radiasi infra merah balik ke permukaan, sehingga akan meningkatkan efek pemanasan. Sebaliknya bila dilihat dari atas, awan tersebut akan memantulkan sinar Matahari dan radiasi infra merah ke angkasa, sehingga meningkatkan efek pendinginan. Apakah efek netto-nya pemanasan atau pendinginan tergantung pada beberapa detail-detail tertentu seperti tipe dan ketinggian awan tersebut. Detail-detail ini sulit direpresentasikan dalam model iklim, antara lain karena awan sangat kecil bila dibandingkan dengan jarak antara batas-batas komputasional dalam model iklim (sekitar 125 hingga 500 km untuk model yang digunakan dalam Laporan Pandangan IPCC ke Empat). Walaupun demikian, umpan balik awan berada pada peringkat dua bila dibandingkan dengan umpan balik uap air dan dianggap positif (menambah pemanasan) dalam semua model yang digunakan dalam Laporan Pandangan IPCC ke Empat.[4]
Umpan balik penting lainnya adalah hilangnya kemampuan memantulkan cahaya (albedo) oleh es.[5] Ketika temperatur global meningkat, es yang berada di dekat kutub mencair dengan kecepatan yang terus meningkat. Bersama dengan melelehnya es tersebut, daratan atau air dibawahnya akan terbuka. Baik daratan maupun air memiliki kemampuan memantulkan cahaya lebih sedikit bila dibandingkan dengan es, dan akibatnya akan menyerap lebih banyak radiasi Matahari. Hal ini akan menambah pemanasan dan menimbulkan lebih banyak lagi es yang mencair, menjadi suatu siklus yang berkelanjutan.
Umpan balik positif akibat terlepasnya CO2 dan CH4 dari melunaknya tanah beku (permafrost) adalah mekanisme lainnya yang berkontribusi terhadap pemanasan. Selain itu, es yang meleleh juga akan melepas CH4 yang juga menimbulkan umpan balik positif.
Kemampuan lautan untuk menyerap karbon juga akan berkurang bila ia menghangat, hal ini diakibatkan oleh menurunya tingkat nutrien pada zona mesopelagic sehingga membatasi pertumbuhan diatom daripada fitoplankton yang merupakan penyerap karbon yang rendah.[6]

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

May 13, 2008

Efek rumah kaca

Segala sumber energi yang terdapat di Bumi berasal dari Matahari. Sebagian besar energi tersebut dalam bentuk radiasi gelombang pendek, termasuk cahaya tampak. Ketika energi ini mengenai permukaan Bumi, ia berubah dari cahaya menjadi panas yang menghangatkan Bumi. Permukaan Bumi, akan menyerap sebagian panas dan memantulkan kembali sisanya. Sebagian dari panas ini sebagai radiasi infra merah gelombang panjang ke angkasa luar. Namun sebagian panas tetap terperangkap di atmosfer bumi akibat menumpuknya jumlah gas rumah kaca antara lain uap air, karbon dioksida, dan metana yang menjadi perangkap gelombang radiasi ini. Gas-gas ini menyerap dan memantulkan kembali radiasi gelombang yang dipancarkan Bumi dan akibatnya panas tersebut akan tersimpan di permukaan Bumi. Hal tersebut terjadi berulang-ulang dan mengakibatkan suhu rata-rata tahunan bumi terus meningkat.

Gas-gas tersebut berfungsi sebagaimana kaca dalam rumah kaca. Dengan semakin meningkatnya konsentrasi gas-gas ini di atmosfer, semakin banyak panas yang terperangkap di bawahnya.

Sebenarnya, efek rumah kaca ini sangat dibutuhkan oleh segala makhluk hidup yang ada di bumi, karena tanpanya, planet ini akan menjadi sangat dingin. Dengan temperatur rata-rata sebesar 15 °C (59 °F), bumi sebenarnya telah lebih panas 33 °C (59 °F) dengan efek rumah kaca^[3] (tanpanya suhu bumi hanya -18 °C sehingga es akan menutupi seluruh permukaan Bumi). Akan tetapi sebaliknya, akibat jumlah gas-gas tersebut telah berlebih di atmosfer, pemanasan global menjadi akibatnya.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

Pemanasan Global

Temperatur rata-rata global 1850 sampai 2006 relatif terhadap 1961–1990

Anomali temperatur permukaan rata-rata selama periode 1995 sampai 2004 dengan dibandingkan pada temperatur rata-rata dari 1940 sampai 1980

Pemanasan global adalah adanya proses peningkatan suhu rata-rata atmosfer, laut, dan daratan Bumi.

Suhu rata-rata global pada permukaan Bumi telah meningkat 0.74 ± 0.18 °C (1.33 ± 0.32 °F) selama seratus tahun terakhir. Intergovernmental Panel on Climate Change (IPCC) menyimpulkan bahwa, "sebagian besar peningkatan temperatur rata-rata global sejak pertengahan abad ke-20 kemungkinan besar disebabkan oleh meningkatnya konsentrasi gas-gas rumah kaca akibat aktivitas manusia"^[1] melalui efek rumah kaca. Kesimpulan dasar ini telah dikemukakan oleh setidaknya 30 badan ilmiah dan akademik, termasuk semua akademi sains nasional dari negara-negara G8. Akan tetapi, masih terdapat beberapa ilmuwan yang tidak setuju dengan beberapa kesimpulan yang dikemukakan IPCC tersebut.

Model iklim yang dijadikan acuan oleh projek IPCC menunjukkan suhu permukaan global akan meningkat 1.1 hingga 6.4 °C (2.0 hingga 11.5 °F) antara tahun 1990 dan 2100.^[1] Perbedaan angka perkiraan itu dikarenakan oleh penggunaan skenario-skenario berbeda mengenai emisi gas-gas rumah kaca di masa mendatang, serta model-model sensitivitas iklim yang berbeda. Walaupun sebagian besar penelitian terfokus pada periode hingga 2100, pemanasan dan kenaikan muka air laut diperkirakan akan terus berlanjut selama lebih dari seribu tahun walaupun tingkat emisi gas rumah kaca telah stabil.^[1] Ini mencerminkan besarnya kapasitas panas dari lautan.

Meningkatnya suhu global diperkirakan akan menyebabkan perubahan-perubahan yang lain seperti naiknya permukaan air laut, meningkatnya intensitas fenomena cuaca yang ekstrim,^[2] serta perubahan jumlah dan pola presipitasi. Akibat-akibat pemanasan global yang lain adalah terpengaruhnya hasil pertanian, hilangnya gletser, dan punahnya berbagai jenis hewan.

Beberapa hal-hal yang masih diragukan para ilmuan adalah mengenai jumlah pemanasan yang diperkirakan akan terjadi di masa depan, dan bagaimana pemanasan serta perubahan-perubahan yang terjadi tersebut akan bervariasi dari satu daerah ke daerah yang lain. Hingga saat ini masih terjadi perdebatan politik dan publik di dunia mengenai apa, jika ada, tindakan yang harus dilakukan untuk mengurangi atau membalikkan pemanasan lebih lanjut atau untuk beradaptasi terhadap konsekwensi-konsekwensi yang ada. Sebagian besar pemerintahan negara-negara di dunia telah menandatangani dan meratifikasi Protokol Kyoto, yang mengarah pada pengurangan emisi gas-gas rumah kaca.

Sumber http://id.wikipedia.org/wiki/Pemanasan_global

May 09, 2008

The Ocean and Global Warming

“The oceans of the world have gotten warmer since the 1940s. Furthermore, it has done so from the surface down towards the bottom of the three oceans, introducing the dimension of depth, something that was not previously actively considered when measuring ocean temperatures. Now the larger driver of the new climate oscillation is the heat we put into the oceans of the world. The world's increasing ocean temperatures have spawned ever-stronger ocean waves over the past 40 years. This energy increases as the ocean’s temperature rises, so the energy content of the tsunamis, hurricanes and typhoons also rises,” said Sinyan Shen, Director of the GWIC in the U.S.

Florida, Louisiana, Mississippi and Alabama were hit by Hurricane Katrina in late August, causing heavy human and economic losses.

The official death toll:

Louisiana	558
Mississippi	218
Alabama	2
Florida	14
U.S. approximately	800

"The American president shuts his eyes to the economic and human damage that the failure to protect the climate inflicts on his country and the world through natural catastrophes like Katrina," Germany's environmental minister, Jurgen Trittin, wrote in an opinion piece printed Aug. 30 in the Frankfurter Rundschau newspaper.

Source http://www.globalwarming.net/index.php?option=com_content&task=view&id=136&Itemid=1

Things you can do today to reduce Global Warming

Take Action!

There are many things you can do in your daily life that can have an effect on your immediate surrounding, and on places as far away as Antarctica. Here is a list of things that you can do to make a difference.

There are many things you can do today to reduce your own adding to on this problem!

Tropical Tree Growth Slowed
Other big changes are being monitored in the tropics, too. Data on tree growth, tropical air temperatures and CO2 readings collected over 16 years indicate that a warming climate may cause the tropical forests to give off more carbon dioxide than they take up. This would upset the common belief that tropical forests are always a counterbalance to carbon, taking huge amounts out of the atmosphere. The study, by Deborah and David Clark of the La Selva Biological Station in Costa Rica, and Charles Keeling and Stephen Piper of the Scripps Institution, reports that rainforest trees grow much more slowly in warmer nighttime temperatures, which is a hallmark of climate change in the tropics.
Tropical Tree Charles Keeling

Landscaping Your Home for Energy Efficiency
In Winter, by maximizing solar heating while deflecting winds away from your home; and
in Summer by maximizing shading while funneling breezes toward your home. [Source]

Buy a Hybrid Car
The average driver could save 16,000 lbs. of carbon dioxide and $3,750 per year driving a hybrid.

Buy a Fuel Efficient Car
Getting a few extra miles per gallon makes a big difference. Save thousands of lbs. of carbon dioxide and a lot of money per year.

Carpool When You Can
Own a big vehicle? Carpooling with friends and co-workers saves fuel. Save 790 lbs. of carbon dioxide and hundreds of dollars per year.

Inflate Your Tires
Keep the tires on your car adequately inflated. Save 250 lbs. of carbon dioxide and $840 per year.

Change Your Air Filter
Check your car's air filter monthly. Save 800 lbs. of carbon dioxide and $130 per year.

Reduce Garbage
Buy products with less packaging and recycle paper, plastic and glass. Save 2,000 lbs. of carbon dioxide per year.
Composting helps reduce greenhouse gas emissions by reducing the number of trips trucks must make to the landfill as well as the amount of methane released by our landfills.

Use Recycled Paper
Make sure your printer paper is 100% post consumer recycled paper. Save 5 lbs. of carbon dioxide per ream of paper.

Buy Minimally Packaged Goods
Less packaging could reduce your garbage by about 10%. Save 1,200 pounds of carbon dioxide and $1,000 per year.

Unplug Un-used Electronics
Even when electronic devices are turned off, they use energy. Save over 1,000 lbs of carbon dioxide and $150 per year.

Plant a Tree
Trees provide a microclimate and sustained moisture for you. Trees suck up carbon dioxide and make clean air for us to breath. Save 2,000 lbs. of carbon dioxide per year.

Use Compact Fluorescent Bulbs
Replace 3 frequently used light bulbs with compact fluorescent bulbs. Save 300 lbs. of carbon dioxide and $60 per year.

Fill the Dishwasher
Run your dishwasher only with a full load. Save 100 lbs. of carbon dioxide and $40 per year.

Adjust Your Thermostat
Move your heater thermostat down two degrees in winter and up two degrees in the summer. Save 2000 lbs of carbon dioxide and $98 per year.

Check Your Waterheater
Keep your water heater thermostat no higher than 120EF. Save 550 lbs. of carbon dioxide and $30 per year.

Change the AC Filter
Clean or replace dirty air conditioner filters as recommended. Save 350 lbs. of carbon dioxide and $150 per year.

Take Shorter Showers
Showers account for 2/3 of all water heating costs. Save 350 lbs. of carbon dioxide and $99 per year.

Install a Low-Flow Showerhead
Using less water in the shower means less energy to heat the water. Save 350 lbs. of carbon dioxide and $150.

Buy Products Locally
Buy locally and reduce the amount of energy required to drive your products to your store.

Buy Energy Certificates
Help spur the renewable energy market and cut global warming pollution by buying wind certificates and green tags.

Insulate Your Water Heater
Keep your water heater insulated could save 1,000 lbs. of carbon dioxide and $40 per year.

Replace Old Appliances
Inefficient appliances waste energy. Save hundreds of lbs. of carbon dioxide and hundreds of dollars per year.

Weatherize Your Home
Caulk and weather strip your doorways and windows. Save 1,700 lbs. of carbon dioxide and $274 per year.

Use a Push Mower
Use your muscles instead of fossil fuels and get some exercise. Save 80 lbs of carbon dioxide and x $ per year.

Put on a Sweater
Instead of turning up the heat in your home, wear more clothes Save 1,000 lbs. of carbon dioxide and $250 per year.

Insulate Your Home
Make sure your walls and ceilings are insulated. Save 2,000 lbs. of carbon dioxide and $245 per year.

Air Dry Your Clothes
Line-dry your clothes in the spring and summer instead of using the dryer. Save 700 lbs. of carbon dioxide and $75 per year.

Switch to a Tankless Water Heater
Your water will be heated as you use it rather than keeping a tank of hot water. Save 300 lbs. of carbon dioxide and $390 per year.

Switch to Double Pane Windows
Double pane windows keep more heat inside your home so you use less energy. Save 10,000 lbs. of carbon dioxide and $436 per year.

Buy Organic Food
The chemicals used in modern agriculture pollute the water supply, and require energy to produce.

Bring Cloth Bags to the Market
Using your own cloth bag instead of plastic or paper bags reduces waste and requires no additional energy.

Source StopGlobalWarming.org

Global Warming Article

Subhankar Banerjee/Associated Press

On Feb. 2, 2007, the United Nations scientific panel studying climate change declared that the evidence of a warming trend is "unequivocal," and that human activity has "very likely" been the driving force in that change over the last 50 years. The last report by the group, the Intergovernmental Panel on Climate Change, in 2001, had found that humanity had "likely" played a role.

The addition of that single word "very" did more than reflect mounting scientific evidence that the release of carbon dioxide and other heat-trapping gases from smokestacks, tailpipes and burning forests has played a central role in raising the average surface temperature of the earth by more than 1 degree Fahrenheit since 1900. It also added new momentum to a debate that now seems centered less over whether humans are warming the planet, but instead over what to do about it. In recent months, business groups have banded together to make unprecedented calls for federal regulation of greenhouse gases. The subject had a red-carpet moment when former Vice President Al Gore's documentary, "An Inconvenient Truth," was awarded an Oscar; and the Supreme Court made its first global warming-related decision, ruling 5 to 4 that the Environmental Protection Agency had not justified its position that it was not authorized to regulate carbon dioxide.

How Global Warming Affects the Ecosystems

Global warming has such a profound impact on the earth’s surface and oceans, it is not surprising that it affects the ecosystems of earth. Species depend on a fairly consistent habitat in which to live. Global warming changes habitats and endangers these species.

One of the habitats already being affected by global warming is the Polar Regions. Vast amounts of ice are melting at both poles. This makes it hard for the species in these regions to survive. For instance, polar bears’ habitat is altered. Where once they could swim a short distance from ice floe to ice floe, that is no longer the case.

Now, the ice floes are so far apart that many polar bears drown trying to make the swim. According to the US Geological Survey, their numbers will decrease by half in the next forty or so years. The melting polar ice cap will be too much for most polar bears to survive. Global warming will eventually lead to their extinction if left unchecked.

Global warming is pushing a reported 2000 species toward the poles. The climate becomes warmer in the habitats the plants and animals are used to. They naturally gravitate towards a cooler climate that will match the earlier climate of the region they left. They were moving at a rate of 3.8 miles per decade.

Another ice habitat being ruined by global warming is the penguins’ home in Antarctica. They have been declining in number rapidly for the last 25 years. In fact, in that amount of time, 33% of the penguins are gone. The global warming melting the ice has made their habitat inhospitable to them.

Global warming may soon make alpine meadows a thing of the past. Already, in Washington’s Olympic Mountains, sub-alpine forests have come in and taken over where alpine meadows once lay. In the last 60 years, species in alpine areas have moved up the mountains at a rate of 20 feet per decade. This leaves little doubt that global warming is having an impact on alpine areas.

The health of sea creatures in their habitats is also being threatened by global warming. In California, sea life is moving northward. This is a behavior designed to keep the creatures at a temperature that is most like the one they are adapted to. They naturally do this as a means of survival. When all the water is too warm, they will have nowhere to go.

Other sea creatures are being put in danger of extinction because of global warming. This happens because the extra carbon dioxide in the air mixes with the ocean water. It changes the acidity of the water.

The sea plants and animals are then in an environment for which they are not suited. If this global warming goes on, many will not be able to survive. For example, 97% of the earth’s coral reefs could disappear if there is a 3.6 degree Fahrenheit rise in temperature. The destruction of ecosystems by global warming has begun. Since all the species are needed to support each other, the whole world will suffer when species are lost. Only a concerted effort on the parts of all human beings will help the situation.

Source http://www.ecologyforlife.info/uncategorized/how-global-warming-affects-the-ecosystems.html

Top 50 Things To Do To Stop Global Warming

Global Warming is a dramatically urgent and serious problem. We don't need to wait for governments to find a solution for this problem: each individual can bring an important help adopting a more responsible lifestyle: starting from little, everyday things. It's the only reasonable way to save our planet, before it is too late.

Here is a list of 50 simple things that everyone can do in order to fight against and reduce the Global Warming phenomenon: some of these ideas are at no cost, some other require a little effort or investment but can help you save a lot of money, in the middle-long term!

Replace a regular incandescent light bulb with a compact fluorescent light bulb (cfl)
CFLs use 60% less energy than a regular bulb. This simple switch will save about 300 pounds of carbon dioxide a year.
Install a programmable thermostat
Programmable thermostats will automatically lower the heat or air conditioning at night and raise them again in the morning. They can save you $100 a year on your energy bill.
Move your thermostat down 2° in winter and up 2° in summer
Almost half of the energy we use in our homes goes to heating and cooling. You could save about 2,000 pounds of carbon dioxide a year with this simple adjustment.
Clean or replace filters on your furnace and air conditioner
Cleaning a dirty air filter can save 350 pounds of carbon dioxide a year.
Choose energy efficient appliances when making new purchases
Look for the Energy Star label on new appliances to choose the most energy efficient products available.
Do not leave appliances on standby
Use the "on/off" function on the machine itself. A TV set that's switched on for 3 hours a day (the average time Europeans spend watching TV) and in standby mode during the remaining 21 hours uses about 40% of its energy in standby mode.
Wrap your water heater in an insulation blanket
You’ll save 1,000 pounds of carbon dioxide a year with this simple action. You can save another 550 pounds per year by setting the thermostat no higher than 50°C.
Move your fridge and freezer
Placing them next to the cooker or boiler consumes much more energy than if they were standing on their own. For example, if you put them in a hot cellar room where the room temperature is 30-35ºC, energy use is almost double and causes an extra 160kg of CO2 emissions for fridges per year and 320kg for freezers.
Defrost old fridges and freezers regularly
Even better is to replace them with newer models, which all have automatic defrost cycles and are generally up to two times more energy-efficient than their predecessors.
Don't let heat escape from your house over a long period
When airing your house, open the windows for only a few minutes. If you leave a small opening all day long, the energy needed to keep it warm inside during six cold months (10ºC or less outside temperature) would result in almost 1 ton of CO2 emissions.
Replace your old single-glazed windows with double-glazing
This requires a bit of upfront investment, but will halve the energy lost through windows and pay off in the long term. If you go for the best the market has to offer (wooden-framed double-glazed units with low-emission glass and filled with argon gas), you can even save more than 70% of the energy lost.
Get a home energy audit
Many utilities offer free home energy audits to find where your home is poorly insulated or energy inefficient. You can save up to 30% off your energy bill and 1,000 pounds of carbon dioxide a year. Energy Star can help you find an energy specialist.
Cover your pots while cooking
Doing so can save a lot of the energy needed for preparing the dish. Even better are pressure cookers and steamers: they can save around 70%!
Use the washing machine or dishwasher only when they are full
If you need to use it when it is half full, then use the half-load or economy setting. There is also no need to set the temperatures high. Nowadays detergents are so efficient that they get your clothes and dishes clean at low temperatures.
Take a shower instead of a bath
A shower takes up to four times less energy than a bath. To maximise the energy saving, avoid power showers and use low-flow showerheads, which are cheap and provide the same comfort.
Use less hot water
It takes a lot of energy to heat water. You can use less hot water by installing a low flow showerhead (350 pounds of carbon dioxide saved per year) and washing your clothes in cold or warm water (500 pounds saved per year) instead of hot.
Use a clothesline instead of a dryer whenever possible
You can save 700 pounds of carbon dioxide when you air dry your clothes for 6 months out of the year.
Insulate and weatherize your home
Properly insulating your walls and ceilings can save 25% of your home heating bill and 2,000 pounds of carbon dioxide a year. Caulking and weather-stripping can save another 1,700 pounds per year. Energy Efficient has more information on how to better insulate your home.
Be sure you’re recycling at home
You can save 2,400 pounds of carbon dioxide a year by recycling half of the waste your household generates.
Recycle your organic waste
Around 3% of the greenhouse gas emissions through the methane is released by decomposing bio-degradable waste. By recycling organic waste or composting it if you have a garden, you can help eliminate this problem! Just make sure that you compost it properly, so it decomposes with sufficient oxygen, otherwise your compost will cause methane emissions and smell foul.
Buy intelligently
One bottle of 1.5l requires less energy and produces less waste than three bottles of 0.5l. As well, buy recycled paper products: it takes less 70 to 90% less energy to make recycled paper and it prevents the loss of forests worldwide.
Choose products that come with little packaging and buy refills when you can
You will also cut down on waste production and energy use... another help against global warming.
Reuse your shopping bag
When shopping, it saves energy and waste to use a reusable bag instead of accepting a disposable one in each shop. Waste not only discharges CO2 and methane into the atmosphere, it can also pollute the air, groundwater and soil.
Reduce waste
Most products we buy cause greenhouse gas emissions in one or another way, e.g. during production and distribution. By taking your lunch in a reusable lunch box instead of a disposable one, you save the energy needed to produce new lunch boxes.
Plant a tree
A single tree will absorb one ton of carbon dioxide over its lifetime. Shade provided by trees can also reduce your air conditioning bill by 10 to 15%. The Arbor Day Foundation has information on planting and provides trees you can plant with membership.
Switch to green power
In many areas, you can switch to energy generated by clean, renewable sources such as wind and solar. In some of these, you can even get refunds by government if you choose to switch to a clean energy producer, and you can also earn money by selling the energy you produce and don't use for yourself.
Buy locally grown and produced foods
The average meal in the United States travels 1,200 miles from the farm to your plate. Buying locally will save fuel and keep money in your community.
Buy fresh foods instead of frozen
Frozen food uses 10 times more energy to produce.
Seek out and support local farmers markets
They reduce the amount of energy required to grow and transport the food to you by one fifth. Seek farmer’s markets in your area, and go for them.
Buy organic foods as much as possible
Organic soils capture and store carbon dioxide at much higher levels than soils from conventional farms. If we grew all of our corn and soybeans organically, we’d remove 580 billion pounds of carbon dioxide from the atmosphere!
Eat less meat
Methane is the second most significant greenhouse gas and cows are one of the greatest methane emitters. Their grassy diet and multiple stomachs cause them to produce methane, which they exhale with every breath.
Reduce the number of miles you drive by walking, biking, carpooling or taking mass transit wherever possible
Avoiding just 10 miles of driving every week would eliminate about 500 pounds of carbon dioxide emissions a year! Look for transit options in your area.
Start a carpool with your coworkers or classmates
Sharing a ride with someone just 2 days a week will reduce your carbon dioxide emissions by 1,590 pounds a year. eRideShare.com runs a free service connecting north american commuters and travelers.
Don't leave an empty roof rack on your car
This can increase fuel consumption and CO2 emissions by up to 10% due to wind resistance and the extra weight - removing it is a better idea.
Keep your car tuned up
Regular maintenance helps improve fuel efficiency and reduces emissions. When just 1% of car owners properly maintain their cars, nearly a billion pounds of carbon dioxide are kept out of the atmosphere.
Drive carefully and do not waste fuel
You can reduce CO2 emissions by readjusting your driving style. Choose proper gears, do not abuse the gas pedal, use the engine brake instead of the pedal brake when possible and turn off your engine when your vehicle is motionless for more than one minute. By readjusting your driving style you can save money on both fuel and car mantainance.
Check your tires weekly to make sure they’re properly inflated
Proper tire inflation can improve gas mileage by more than 3%. Since every gallon of gasoline saved keeps 20 pounds of carbon dioxide out of the atmosphere, every increase in fuel efficiency makes a difference!
When it is time for a new car, choose a more fuel efficient vehicle
You can save 3,000 pounds of carbon dioxide every year if your new car gets only 3 miles per gallon more than your current one. You can get up to 60 miles per gallon with a hybrid! You can find information on fuel efficiency on FuelEconomy and on GreenCars websites.
Try car sharing
Need a car but don’t want to buy one? Community car sharing organizations provide access to a car and your membership fee covers gas, maintenance and insurance. Many companies – such as Flexcar - offer low emission or hybrid cars too! Also, see ZipCar.
Try telecommuting from home
Telecommuting can help you drastically reduce the number of miles you drive every week. For more information, check out the Telework Coalition.
Fly less
Air travel produces large amounts of emissions so reducing how much you fly by even one or two trips a year can reduce your emissions significantly. You can also offset your air travel carbon emissions by investingin renewable energy projects.
Encourage your school or business to reduce emissions
You can extend your positive influence on global warming well beyond your home by actively encouraging other to take action.
Join the virtual march
The Stop Global Warming Virtual March is a non-political effort to bring people concerned about global warming together in one place. Add your voice to the hundreds of thousands of other people urging action on this issue.
Encourage the switch to renewable energy
Successfully combating global warming requires a national transition to renewable energy sources such as solar, wind and biomass. These technologies are ready to be deployed more widely but there are regulatory barriers impeding them. U.S. citizens, take action to break down those barriers with Vote Solar.
Protect and conserve forest worldwide
Forests play a critial role in global warming: they store carbon. When forests are burned or cut down, their stored carbon is release into the atmosphere - deforestation now accounts for about 20% of carbon dioxide emissions each year. Conservation International has more information on saving forests from global warming.
Consider the impact of your investments
If you invest your money, you should consider the impact that your investments and savings will have on global warming. Check out SocialInvest and Ceres to can learn more about how to ensure your money is being invested in companies, products and projects that address issues related to climate change.
Make your city cool
Cities and states around the country have taken action to stop global warming by passing innovative transportation and energy saving legislation. If you're in the U.S., join the cool cities list.
Tell Congress to act
The McCain Lieberman Climate Stewardship and Innovation Act would set a firm limit on carbon dioxide emissions and then use free market incentives to lower costs, promote efficiency and spur innovation. Tell your representative to support it.
Make sure your voice is heard!
Americans must have a stronger commitment from their government in order to stop global warming and implement solutions and such a commitment won’t come without a dramatic increase in citizen lobbying for new laws with teeth. Get the facts about U.S. politicians and candidates at Project Vote Smart and The League of Conservation Voters. Make sure your voice is heard by voting!
Share this list!
Send this page via e-mail to your friends! Spread this list worldwide and help people doing their part: the more people you will manage to enlighten, the greater YOUR help to save the planet will be (but please take action on first person too)!

If you like, you are free to republish, adapt or translate the list and post it in your blog, website or forum as long as you give us credit with a link to the original source.
Thank you.

If you wish, you can download this page as PDF: print it (on recycled paper sheets, of course), stick it to your office/room walls, or send it to your friends!

Source http://globalwarming-facts.info/50-tips.html

How Global Warming Affects the Ecosystems

Source
http://www.ecologyforlife.info/uncategorized/how-global-warming-affects-the-ecosystems.html

Related climatic issues

Main articles: Ocean acidification, global dimming, and ozone depletion

A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO₂ increases the amount of CO₂ dissolved in the oceans.^[116] CO₂ dissolved in the ocean reacts with water to form carbonic acid, resulting in acidification. Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004,^[117] and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO₂.^[1]^[118] Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO₂, that could disrupt food webs and impact human societies that depend on marine ecosystem services.^[119]

Global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface, may have partially mitigated global warming in the late twentieth century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.^[1]

Ozone depletion, the steady decline in the total amount of ozone in Earth's stratosphere, is frequently cited in relation to global warming. Although there are areas of linkage, the relationship between the two is not strong.

Source http://en.wikipedia.org/wiki/Global_warming

Social and political debate

Main articles: Global warming controversy, Politics of global warming, and Economics of global warming

See also: Climate change denial

Per capita greenhouse gas emissions in 2000, including land-use change.

Per country greenhouse gas emissions in 2000, including land-use change.

Since the last decades of the 20th century, increased awareness of the scientific findings surrounding global warming has resulted in political and economic debate.^[100] Poor regions, particularly Africa, appear at greatest risk from the projected effects of global warming, while their emissions have been small compared to the developed world.^[101] At the same time, developing country exemptions from provisions of the Kyoto Protocol have been criticized by the United States and Australia, and used as part of a rationale for continued non-ratification by the U.S.^[102] In the Western world, the idea of human influence on climate has gained wider public acceptance in Europe than in the United States.^[103]^[104]

The issue of climate change has sparked debate weighing the benefits of limiting industrial emissions of greenhouse gases against the costs that such changes would entail. There has been discussion in several countries about the cost and benefits of adopting alternative energy sources in order to reduce carbon emissions.^[105] Organizations and companies such as the Competitive Enterprise Institute and ExxonMobil have emphasized more conservative climate change scenarios while highlighting the potential economic cost of stricter controls.^[106]^[107]^[108]^[109] Likewise, various environmental lobbies and a number of public figures have launched campaigns to emphasize the potential risks of climate change and promote the implementation of stricter controls. Some fossil fuel companies have scaled back their efforts in recent years,^[110] or called for policies to reduce global warming.^[111]

Another point of contention is the degree to which emerging economies such as India and China should be expected to constrain their emissions. According to recent reports, China's gross national CO₂ emissions may now exceed those of the U.S. ^[112] China has contended that it has less of an obligation to reduce emissions since its per capita emissions are roughly one-fifth that of the United States.^[113] India, also exempt from Kyoto restrictions and another of the biggest sources of industrial emissions, has made similar assertions.^[114] However, the U.S. contends that if they must bear the cost of reducing emissions, then China should do the same.^[115]

Source http://en.wikipedia.org/wiki/Global_warming

Adaptation and mitigation

Main articles: Adaptation to global warming, Mitigation of global warming, and Kyoto Protocol

The broad agreement among climate scientists that global temperatures will continue to increase has led some nations, states, corporations and individuals to implement actions to try to curtail global warming or adjust to it. Many environmental groups encourage individual action against global warming, often by the consumer, but also by community and regional organizations. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO₂ emissions.^[90]^[91]

There has also been business action on climate change, including efforts at increased energy efficiency and limited moves towards use of alternative fuels. One important innovation has been the development of greenhouse gas emissions trading through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances.

The world's primary international agreement on combating global warming is the Kyoto Protocol, an amendment to the UNFCCC negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55% of global greenhouse gas emissions.^[92] Only the United States and Kazakhstan have not ratified the treaty, with the United States historically being the world's largest emitter of greenhouse gas. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one.^[93]

Claiming "serious harm" to the United States economy and the exemption of "80 percent of the world, including major population centers" like China and India from the treaty, George W. Bush contends that the Kyoto Protocol is an unfair and ineffective means of addressing global climate change concerns.^[94] Bush has promoted improved energy technology as a means to combat climate change,^[95] and various state and city governments within the United States have begun their own initiatives to indicate support and compliance with the Kyoto Protocol on a local basis; an example of this being the Regional Greenhouse Gas Initiative.^[96]

China and India, though exempt from its provisions as developing countries, have ratified the Kyoto Protocol. China may have passed the U.S. in total annual greenhouse gas emissions according to some recent studies. Chinese Premier Wen Jiabao has called on the nation to redouble its efforts to tackle pollution and global warming.^[97]

The IPCC's Working Group III is responsible for crafting reports that deal with the mitigation of global warming and analyzing the costs and benefits of different approaches. In the 2007 IPCC Fourth Assessment Report, they conclude that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as energy supply, transportation, industry, and agriculture, that should be implemented to reduced global emissions. They estimate that stabilization of carbon dioxide equivalent between 445 and 710 ppm by 2030 will result in between a 0.6% increase and 3% decrease in global gross domestic product.^[98] According to Working Group III, to limit temperature rise to 2 Degrees Centigrade, "developed countries as a group would need to reduce their emissions to below 1990 levels in 2020 (on the order of –10% to 40% below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40% (Sic. 80% in Box 13.7, p776) to 95% below 1990 levels), even if developing countries make substantial reductions."^[99]

Source http://en.wikipedia.org/wiki/Global_warming

Attributed and expected effects

Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the WGMS and the NSIDC.

Main article: Effects of global warming

Although it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause broader changes, including glacial retreat, Arctic shrinkage, and worldwide sea level rise. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, addition of new trade routes,^[75] reduced summer streamflows, species extinctions, and increases in the range of disease vectors.

Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as that of the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events, are being attributed in part to global warming.^[76] While changes are expected for overall patterns, intensity, and frequencies, it is difficult to attribute specific events to global warming. Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects from warmer temperatures.^[77]

Increasing deaths, displacements, and economic losses projected due to extreme weather attributed to global warming may be exacerbated by growing population densities in affected areas, although temperate regions are projected to experience some benefits, such as fewer deaths due to cold exposure.^[78] A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II.^[76] The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature, but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.^[1]

Additional anticipated effects include sea level rise of 110 to 770 millimeters (0.36 to 2.5 ft) between 1990 and 2100,^[79] repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increased intensity of hurricanes and extreme weather events, lowering of ocean pH, and the spread of diseases such as malaria and dengue fever. One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections.^[80] However, few mechanistic studies have documented extinctions due to recent climate change^[81] and one study suggests that projected rates of extinction are uncertain.^[82]

Economic

The projected temperature increase for a range of stabilization scenarios (the colored bands). The black line in middle of the shaded area indicates 'best estimates'; the red and the blue lines the likely limits. From the work of IPCC AR4.

Main articles: Economics of global warming and Low-carbon economy

Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far failed to reach conclusive findings; in a survey of 100 estimates, the values ran from US$-10 per tonne of carbon (tC) (US$-3 per tonne of carbon dioxide) up to US$350/tC (US$95 per tonne of carbon dioxide), with a mean of US$43 per tonne of carbon (US$12 per tonne of carbon dioxide).^[78] One widely publicized report on potential economic impact is the Stern Review; it suggests that extreme weather might reduce global gross domestic product by up to 1%, and that in a worst-case scenario global per capita consumption could fall 20%.^[83] The report's methodology, advocacy and conclusions have been criticized by many economists, primarily around the Review's assumptions of discounting and its choices of scenarios,^[84] while others have supported the general attempt to quantify economic risk, even if not the specific numbers.^[85]^[86]

Preliminary studies suggest that costs and benefits of mitigating global warming are broadly comparable in magnitude.^[87]

According to United Nations Environment Programme (UNEP), economic sectors likely to face difficulties related to climate change include banks, agriculture, transport and others.^[88] Developing countries dependent upon agriculture will be particularly harmed by global warming.^[89]

Source http://en.wikipedia.org/wiki/Global_warming

Climate Models

Calculations of global warming prepared in or before 2001 from a range of climate models under the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions.

The geographic distribution of surface warming during the 21^st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F).

Main article: Global climate model

Scientists have studied global warming with computer models of the climate. These models are based on physical principles of fluid dynamics, radiative transfer, and other processes, with simplifications being necessary because of limitations in computer power and the complexity of the climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes.^[68]These models predict that the effect of adding greenhouse gases is to produce a warmer climate.^[69] However, even when the same assumptions of future greenhouse gas levels are used, there still remains a considerable range of climate sensitivity.

Including uncertainties in future greenhouse gas concentrations and climate modeling, the IPCC anticipates a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) by the end of the 21st century, relative to 1980–1999.^[1] Models have also been used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human-derived causes.

Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate.^[70] These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.

Global climate model projections of future climate are forced by imposed greenhouse gas emission scenarios, most often from the IPCC Special Report on Emissions Scenarios (SRES). Less commonly, models may also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain (under the A2 SRES scenario, responses vary between an extra 20 and 200 ppm of CO₂). Some observational studies also show a positive feedback.^[71]^[72]^[73]

The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.^[74]

Source http://en.wikipedia.org/wiki/Global_warming

Temperature changes

Two millennia of mean surface temperatures according to different reconstructions, each smoothed on a decadal scale. The unsmoothed, annual value for 2004 is also plotted for reference.

Main article: Temperature record

Recent

Global temperatures on both land and sea have increased by 0.75 °C (1.35 °F) relative to the period 1860–1900, according to the instrumental temperature record. This measured temperature increase is not significantly affected by the urban heat island effect.^[54] Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).^[55] Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.

Sea temperatures increase more slowly than those on land both because of the larger effective heat capacity of the oceans and because the ocean can lose heat by evaporation more readily than the land.^[56] The Northern Hemisphere has more land than the Southern Hemisphere, so it warms faster. The Northern Hemisphere also has extensive areas of seasonal snow and sea-ice cover subject to the ice-albedo feedback. More greenhouse gases are emitted in the Northern than Southern Hemisphere, but this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.

Based on estimates by NASA's Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.^[57] Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998.^[58]^[59] Temperatures in 1998 were unusually warm because the strongest El Niño in the past century occurred during that year.^[60]

Anthropogenic emissions of other pollutants—notably sulfate aerosols—can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century,^[61] though the cooling may also be due in part to natural variability. James Hansen and colleagues have proposed that the effects of the products of fossil fuel combustion—CO₂ and aerosols—have largely offset one another, so that warming in recent decades has been driven mainly by non-CO₂ greenhouse gases.^[62]

Paleoclimatologist William Ruddiman has argued that human influence on the global climate began around 8,000 years ago with the start of forest clearing to provide land for agriculture and 5,000 years ago with the start of Asian rice irrigation.^[63] Ruddiman's interpretation of the historical record, with respect to the methane data, has been disputed.^[64]

Pre-human climate variations

Curves of reconstructed temperature at two locations in Antarctica and a global record of variations in glacial ice volume. Today's date is on the left side of the graph.

Further information: Paleoclimatology

See also: Snowball Earth

Earth has experienced warming and cooling many times in the past. The recent Antarctic EPICA ice core spans 800,000 years, including eight glacial cycles timed by orbital variations with interglacial warm periods comparable to present temperatures.^[65]

A rapid buildup of greenhouse gases amplified warming in the early Jurassic period (about 180 million years ago), with average temperatures rising by 5 °C (9 °F). Research by the Open University indicates that the warming caused the rate of rock weathering to increase by 400%. As such weathering locks away carbon in calcite and dolomite, CO₂ levels dropped back to normal over roughly the next 150,000 years.^[66]^[67]

Sudden releases of methane from clathrate compounds (the clathrate gun hypothesis) have been hypothesized as both a cause for and an effect of other warming events in the distant past, including the Permian–Triassic extinction event (about 251 million years ago) and the Paleocene–Eocene Thermal Maximum (about 55 million years ago).

Source http://en.wikipedia.org/wiki/Global_warming

Causes

Main articles: Attribution of recent climate change and Scientific opinion on climate change

The Earth's climate changes in response to external forcing, including variations in its orbit around the Sun (orbital forcing),^[14]^[15]^[16], changes in solar luminosity, volcanic eruptions,^[17] and atmospheric greenhouse gas concentrations. The detailed causes of the recent warming remain an active field of research, but the scientific consensus^[18]^[19] is that the increase in atmospheric greenhouse gases due to human activity caused most of the warming observed since the start of the industrial era. This attribution is clearest for the most recent 50 years, for which the most detailed data are available. Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity.^[20]^[21]^[22]

None of the effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.^[23]

Greenhouse gases in the atmosphere

Main articles: Greenhouse gas and Greenhouse effect

The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet's lower atmosphere and surface.

Existence of the greenhouse effect as such is not disputed. Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable.^[24]^[25] On Earth, the major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect (not including clouds); carbon dioxide (CO₂), which causes 9–26%; methane (CH₄), which causes 4–9%; and ozone, which causes 3–7%.^[26]^[27] The issue is how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of some greenhouse gases.

Human activity since the industrial revolution has increased the concentration of various greenhouse gases, leading to increased radiative forcing from CO₂, methane, tropospheric ozone, CFCs and nitrous oxide. Molecule for molecule, methane is a more effective greenhouse gas than carbon dioxide, but its concentration is much smaller so that its total radiative forcing is only about a fourth of that from carbon dioxide. Some other naturally occurring gases contribute very small fractions of the greenhouse effect; one of these, nitrous oxide (N₂O), is increasing in concentration owing to human activity such as agriculture. The atmospheric concentrations of CO₂ and CH₄ have increased by 31% and 149% respectively since the beginning of the industrial revolution in the mid-1700s. These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores.^[28] From less direct geological evidence it is believed that CO₂ values this high were last attained 20 million years ago.^[29] Fossil fuel burning has produced approximately three-quarters of the increase in CO₂ from human activity over the past 20 years. Most of the rest is due to land-use change, in particular deforestation.^[30]

Recent increases in atmospheric carbon dioxide (CO₂). The monthly CO₂ measurements display small seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the Northern Hemisphere's late spring, and declines during the Northern Hemisphere growing season as plants remove some CO₂ from the atmosphere.

The present atmospheric concentration of CO₂ is about 385 parts per million (ppm) by volume.^[31] Future CO₂ levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, and natural developments, but may be ultimately limited by the availability of fossil fuels. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO₂ scenarios, ranging from 541 to 970 ppm by the year 2100.^[32] Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or methane clathrates are extensively used.^[33] Research by NASA climate scientist James Hansen indicates the 0.75° rise in average global temperatures over the last 100 years has been driven mainly by greenhouse gases other than carbon dioxide.^[34]

Feedbacks

Main article: Effects of global warming

The effects of forcing agents on the climate are complicated by various feedback processes.

One of the most pronounced feedback effects relates to the evaporation of water. Warming by the addition of long-lived greenhouse gases such as CO₂ will cause more water to evaporate into the atmosphere. Since water vapor itself acts as a greenhouse gas, the atmosphere warms further; this warming causes more water vapor to evaporate (a positive feedback), and so on until other processes stop the feedback loop. The result is a much larger greenhouse effect than that due to CO₂ alone. Although this feedback process causes an increase in the absolute moisture content of the air, the relative humidity stays nearly constant or even decreases slightly because the air is warmer.^[35] This feedback effect can only be reversed slowly as CO₂ has a long average atmospheric lifetime.

Feedback effects due to clouds are an area of ongoing research. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud. These details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models. Nevertheless, cloud feedback is second only to water vapor feedback and is positive in all the models that were used in the IPCC Fourth Assessment Report.^[35]

A subtler feedback process relates to changes in the lapse rate as the atmosphere warms. The atmosphere's temperature decreases with height in the troposphere. Since emission of infrared radiation varies with the fourth power of temperature, longwave radiation emitted from the upper atmosphere is less than that emitted from the lower atmosphere. Most of the radiation emitted from the upper atmosphere escapes to space, while most of the radiation emitted from the lower atmosphere is re-absorbed by the surface or the atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height: if the rate of temperature decrease is greater the greenhouse effect will be stronger, and if the rate of temperature decrease is smaller then the greenhouse effect will be weaker. Both theory and climate models indicate that warming will reduce the decrease of temperature with height, producing a negative lapse rate feedback that weakens the greenhouse effect. Measurements of the rate of temperature change with height are very sensitive to small errors in observations, making it difficult to establish whether the models agree with observations.^[36]

Another important feedback process is ice-albedo feedback.^[37] When global temperatures increase, ice near the poles melts at an increasing rate. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.

Positive feedback due to release of CO₂ and CH₄ from thawing permafrost, such as the frozen peat bogs in Siberia, is an additional mechanism that could contribute to warming.^[38] Similarly a massive release of CH₄ from methane clathrates in the ocean could cause rapid warming, according to the clathrate gun hypothesis.

The ocean's ability to sequester carbon is expected to decline as it warms. This is because the resulting low nutrient levels of the mesopelagic zone (about 200 to 1000 m depth) limits the growth of diatoms in favor of smaller phytoplankton that are poorer biological pumps of carbon.^[39]

Solar variation

Solar variation over the last thirty years.

Main article: Solar variation

A few papers suggest that the Sun's contribution may have been underestimated. Two researchers at Duke University, Bruce West and Nicola Scafetta, have estimated that the Sun may have contributed about 45–50% of the increase in the average global surface temperature over the period 1900–2000, and about 25–35% between 1980 and 2000.^[40] A paper by Peter Stott and other researchers suggests that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.^[41] They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases.

A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming.^[42] It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.^[43]

One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas greenhouse gas theory predicts cooling there.^[44] The observed trend since at least 1960 has been a cooling of the lower stratosphere.^[45] Reduction of stratospheric ozone also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.^[46] Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since.^[1] In 2006, Peter Foukal and other researchers from the United States, Germany, and Switzerland found no net increase of solar brightness over the last thousand years. Solar cycles led to a small increase of 0.07% in brightness over the last thirty years. This effect is far too small to contribute significantly to global warming.^[47]^[48] A paper by Mike Lockwood and Claus Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays.^[49] Henrik Svensmark and Eigil Friis-Christensen, the main proponents of cloud seeding by galactic cosmic rays, disputed this criticism of their hypothesis.^[50] A 2007 paper found that in the last 20 years there has been no significant link between changes in cosmic rays coming to Earth and cloudiness and temperature.^[51]^[52]^[53]

Source http://en.wikipedia.org/wiki/Global_warming

Terminology

The term "global warming" refers to the warming in recent decades and its projected continuation, and implies a human influence.^[11]^[12] The United Nations Framework Convention on Climate Change (UNFCCC) uses the term "climate change" for human-caused change, and "climate variability" for other changes.^[13] The term "anthropogenic global warming" (AGW) is sometimes used when focusing on human-induced changes.

Source http://en.wikipedia.org/wiki/Global_warming

Global Warming

This article is about the current period of increasing global temperature. For other periods of warming in Earth's history, see Palaeoclimatology and Geologic temperature record.

Global mean surface temperature anomaly relative to 1961–1990

Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980

Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-twentieth century, and its projected continuation.

The average global air temperature near the Earth's surface increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the hundred years ending in 2005.^[1] The Intergovernmental Panel on Climate Change (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations"^[1] via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.^[2]^[3]

These basic conclusions have been endorsed by at least thirty scientific societies and academies of science,^[4] including all of the national academies of science of the major industrialized countries.^[5]^[6]^[7] While individual scientists have voiced disagreement with some findings of the IPCC,^[8] the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.^[9]^[10]

Climate model projections summarized by the IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.^[1] The range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a thousand years even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans.^[1]

Increasing global temperature will cause sea level to rise, and is expected to increase the intensity of extreme weather events and to change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors.

Remaining scientific uncertainties include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the globe. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions, but there is ongoing political and public debate worldwide regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences.

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