Selasa, 08 April 2008

Lempengan Es Antartika Kian Mengkhawatirkan





WASHINGTON - Efek pemanasan global makin mengkhawatirkan. Bongkahan es seluas 414 kilometer persegi (hampir 1,5 kali luas Surabaya, Red) di Antartika mulai meleleh akibat efek tersebut. Gambar satelit Pusat Data Es dan Salju Universitas Colorado (NSIDC) menunjukkan reruntuhan bongkahan es tersebut terjadi mulai 28 Februari lalu.

Menurut peneliti, bongkahan es berbentuk lempengan yang sangat besar itu mengambang permanen di sekitar 1.609 kilometer selatan Amerika Selatan, barat daya Semenanjung Antartika. Padahal, diyakini bongkahan es itu berada di sana sejak 1.500 tahun lalu. “Ini akibat pemanasan global,” ujar ketua peneliti NSIDC Ted Scambos. Menurut dia, lempengan es yang disebut Wilkins Ice Shelf itu sangat jarang ambrol.

Sekarang, setelah adanya perpecahan itu, bongkahan es yang tersisa tinggal 12.950 kilometer persegi, ditambah 5,6 kilometer potongan es yang berdekatan dan menghubungkan dua pulau. “Sedikit lagi, bongkahan es terakhir ini bisa turut amblas. Dan, separo total area es bakal hilang dalam beberapa tahun mendatang,” ujar Scambos.

Perpecahan paling dramatis terjadi pada 2002 dan 1995. Masing-masing 3.850 kilometer persegi dan 2.625 kilometer persegi. Runtuhnya bongkahan es di Antartika dalam 50 tahun terakhir telah mencapai 13 ribu kilometer persegi. Ini dapat meningkatkan level air laut di dunia. Berdasarkan kalkulasi, level permukaan air laut meningkat 3 milimeter per tahun. Level permukaan samudera dapat meningkat 1,4 meter pada akhir abad ke-21.

Diperkirakan Wilkins Ice Shelf akan benar-benar runtuh 15 tahun lagi. Memang, bagian yang baru saja amblas hanya sekitar 4 persen dari ukuran total. Tapi, itu bagian terpenting dan mengancam keruntuhan lanjutan.

Masih ada kesempatan hingga tahun depan untuk mempertahankan lempengan es yang tersisa. Sebab, ini akhir dari suhu panas di Antartika dan mulai masuk suhu dingin.

“Beberapa kejadian akhir-akhir ini merupakan titik yang memicu dalam perubahan sistem,” ujar Sarah Das, peneliti dari Institut Kelautan Wood Hole. Perubahan di Antartika sangat kompleks dan lebih terisolasi dari seluruh bagian dunia.

Antartika di Kutub Selatan adalah daratan benua dengan wilayah pegunungan dan danau berselimut es yang dikelilingi lautan. Benua ini jauh lebih dingin daripada Artik, sehingga lapisan es di sana sangat jarang meleleh, bahkan ada lapisan yang tidak pernah mencair dalam sejarah. Temperatur rata-ratanya minus 49 derajat Celsius, tapi pernah mencapai hampir minus 90 derajat celsius pada Juli 1983. Tak heran jika fenomena mencairnya es di benua yang mengandung hampir 90 persen es di seluruh dunia itu mendapat perhatian serius peneliti. (AP/AFP/erm/ami)

Selasa, 01 April 2008

global warming

global warming

Today the IPCC released its 4th installment of its report on global warming. It has found that only .12 percent of world GDP would be needed to stave off the harmful effects of climate change. Echoing the Stern Report it shows that the only thing we should be afraid of is doing nothing. The report focused on economic changes that need to be made, pointing out that emissions must start declining by the year 2015 to prevent the world’s temperature from rising more than 2 degrees Celsius over pre-industrialized temperatures. (a scenario that would be catastrophic)

Read the summary for policy makers here (doc)

While some governments try to delay action, the switch to a cleaner and more efficient energy system is already underway, according to a new report from WWF.

A new briefing from the global conservation organization, Stop Climate Change: It Is Possible highlights 15 ways in which people, business and governments work with WWF to reduce CO2 emissions and help slow global warming.

The report highlights initiatives from around the world, ranging from India to Brazil, that save energy and reduce carbon pollution.

In Thailand, a new law encourages the clean production of energy from biofuel plants that will feed into the electricity grid. Elsewhere, major businesses have signed up for WWF’s Climate Savers programme and are actively reducing their carbon emissions. And in the UK a new campaign shows that people can simply unplug their phone chargers to cut standby power consumption.

“Taking action brings real savings and other benefits to consumers and businesses while preventing dangerous climate change,” says Hans Verolme, Director of WWF’s Global Climate Change Programme. “The planet is running a fever and people are working with WWF to cool it - global warming is costing us dearly already but by acting now we can avoid future calamities.”

The Intergovernmental Panel on Climate Change’s (IPCC’s) third working group, meeting in Bangkok today, showed that the cost of doing nothing about global warming is far higher than the cost of cleaning up our economies.

The WWF has said that to stay below a dangerous rise in temperature of 2°C the world needs to reduce global CO2 emissions by over 50 per cent by the middle of this century. Independent economic assessments have confirmed that this pays off. A claim backed up in todays report.

“We have all the technological and economic tools available today - governments now need to implement clean energy solutions and remove the obstacles that still prevent their break-through,” says Dr Stephan Singer, Head of WWF’s European Climate Change Program and expert reviewer of the report by IPCC Working Group III. “The facts are clear - preventing climate change is the best deal for the global economy, so why are we still waiting?”

In my view, climate change is the most severe problem that we are facing today -- more serious even than the threat of terrorism."

With this warning to an international science meeting in February 2004, David A. King, Chief Scientific Advisor to the British Government, brought the issue of global warming into sharp focus.

The World View of Global Warming project is documenting this change through science photography from the Arctic to Antarctica, from glaciers to the oceans, across all climate zones. Rapid climate change and its effects is fast becoming one of the prime events of the 21st century. It is real and it is accelerating across the globe. As the effects of this change combine with overpopulation and weather crises, climate disruptions will affect more people than does war.

The 2005 average global temperature equaled (within several hundredths of a degree) the record warm year of 1998, according to meteorologists. 2002-4 were nearly as warm, and the 11 warmest years on record have all occurred since 1990. In response, our planet has been changing with warming winds and rising seas. At the poles and in mountains, ice is under fire and glaciers are receding. Down into the temperate zone, change is rearranging the boundaries of life. The plants and animals with whom we share the planet are adapting and moving -- some even going extinct -- because they have no choice.

We six billion humans are being affected, too. Coastal towns are suffering from rising sea level, storms are getting stronger and 35,000 people died in European heat waves in 2003. However, we have choices to make to help correct and ameliorate global warming. This is a story of frightening scale and and great urgency that is just beginning to be told. Please go to Actions to see what you can do now.

I began photographing climate change in 1999, about when scientists started to realize how great a change in temperatures is taking place in our time. Past earth temperatures left their mark in tree rings, glaciers and ancient lake and ocean sediments, and the record shows slowly decreasing temperatures over the last 2000 years. In that time there have been warm and cool periods, but nothing like the rise in temperatures in the past 150 years -- and no increase even close to the past 30. This research has created what has become the single most powerful icon of climate change, the so-called "hockey-stick" graph of temperatures. In 2005-6 it was subjected to intense re-analysis. Evidence of previous cool and warm periods has increased, but the rapid and sustained heat gain especially since the 1970s remains unparalleled in recent earth history.

chartIn general global temperatures have risen since the 19th century industrial revolution. There is little scientific question the reason is a steep increase in atmospheric carbon dioxide -- CO2 -- from human use of fossil fuels. Methane, ozone, other gases and dusts have also increased greatly. The mechanism of our atmosphere is that gases like CO2 and methane trap some of the sun's radiation and hold it in the lower atmosphere, heating it. The natural greenhouse effect made the earth warm enough for life, but the effect is much higher now. Ice core records show that whenever CO2 has increased in the earth's past, so has temperature. The recent increase in atmospheric CO2 is 200 times as great as any previous change seen in the ice cores. The current level is 380 parts per million, the highest in more than 650,000 years. It shows no signs of decreasing.

CHARTThis increase caused earth's average atmospheric temperature to go up about 1. degree F in the 20th century. Now, according to NOAA, the global warming rate in the last 25 years has risen to 3.6 degrees F per century. This tends to confirm the predictions of temperature increases made by international panels of climate scientists (IPCC). The ocean has actually absorbed most of the added CO2 and heat -- becoming warmer and very slightly more acidic. These increases, seemingly small, have a giant effect on weather, climate zones, plants and animals, sea life, glaciers and river flow -- and thus human life. My project and this Web site seek to document these changes. For more on past climate and today's weather, see especially the Paleoclimate and Weather sections.

Kamis, 06 Maret 2008

Jangan d1 tiru



untuk semua blogger ini pesan dari wijo (sehat) :

mari kita selamatkan bumi dari pemanasan global.kami comunitas anak sehat menyatakan perang terhadap penebang hutan dan bentuk kejahatan lingkungan.

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