Arctic Ice Melt 'Alarming'

Al Jazeera
03 May 2011

Ocean could be ice-free in summers within 40 years and sea levels could rise by 1.6 metres by 2100, says new study.

Ice in Greenland and the rest of the Arctic is melting dramatically faster than was earlier projected and could raise global sea levels by as much as 1.6 metres by 2100, says a new study.

The study released on Tuesday by the Arctic Monitoring and Assessment Program (AMAP) said there is a "need for greater urgency" in fighting global warming as record temperatures have led to the increased rate of melting.

The AMAP report said the correspondending rise in water levels will directly threaten low-lying coastal areas such as Florida and Bangladesh, but would also affect islands and cities from London to Shanghai. The report says it will also increase the cost of rebuilding tsunami barriers in Japan.

"The past six years (until 2010) have been the warmest period ever recorded in the Arctic," said the report.

"In the future, global sea level is projected to rise by 0.9 metres to 1.6 metres by 2100 and the loss of ice from Arctic glaciers, ice caps and the Greenland ice sheet will make a substantial contribution," it added.

The rises had been projected from levels recorded in 1990.

Dramatic rise from projections

In its last major study in 2007, the United Nations' Intergovernmental Panel on Climate Change (IPCC) said that sea levels were likely to rise by only between 18 and 59 centimetres by 2100, though those numbers did not include any possible acceleration due to a thaw in the polar regions.

The new AMAP assessment says that Greenland lost ice in the 2004-2009 period four times faster than it did between 1995-2000.

The AMAP is the scientific arm of the eight-nation Arctic Council.

Foreign ministers from council nations - the United States, Russia, Canada, Sweden, Finland, Denmark, Norway and Iceland -- are due to meet in Greenland on May 12, and will discuss the AMAP report's findings.

The report will first be discussed by about 400 international scientists at a conference this week in Copenhagen, Denmark.

"The increase in annual average temperature since 1980 has been twice as high over the Arctic as it has been over the rest of the world," the report said. Temperatures were higher than at any time in the past 2,000 years."

In its report, the IPCC had said that it was at least 90 per cent probable that emissions of greenhouse gases by human beings, including the burning of fossil fuels, were to blame for most of the warming in recent decades.

"It is worrying that the most recent science points to much higher sea level rise than we have been expecting until now," Connie Hedegaard, the European Climate Commissioner, told the Reuters news agency.

"The study is yet another reminder of how pressing it has become to tackle climate change, although this urgency is not always evident neither in the public debate nor from the pace in the international negotiations," she said.

UN talks on a global accord to combat climate change have been making slow progress, and the organisation says national promises to limit greenhouse gas emissions are now insufficent to avoid possibly catastrophic consequences of global temperature rises.

Arctic could be ice-free

The AMAP study, which drew on the work of hundreds of experts, said that there were signs warming in the Arctic was accelerating, and that the Arctic Ocean could be nearly free of ice in the summers within 30 or 40 years. This, too, was higher than projected by the IPCC.

While the thaw would make the Arctic more accessible for oil exploration, mining and shipping, it would also disrupt the livelihoods of people who live there, as well as threaten the survival of creatures such as polar bears.

"There is evidence that two components of the Arctic cryosphere - snow and sea ice - are interacting with the climate system to accelerate warming," the report said.

The IPCC estimate was based largely on the expansion of ocean waters from warming and the runoff from
melting land glaciers elsewhere in the world.

The AMAP report says that Arctic temperatures in the past six years have been at their highest levels since measurements began in 1880, and the rises were being fed by "feedback" mechanisms in the far north.

One such mechanism involves the ocean absorbing more heat as a result of not being covered by ice, as ice reflects solar energy. While the effect had been predicted by scientists earlier, the AMAP report says that "clear evidence for it has only been observed in the past five years".

Temperature rises expected

It projected that average fall and winter temperatures in the Arctic will climb by roughly 2.8 to 6.1 degrees Celsius by 2080, even if greenhouse gas emissions are lower than in the past decade.

"The observed changes in sea ice on the Arctic Ocean, in the mass of the Greenland ice sheet and Arctic ice caps and glaciers over the past 10 years are dramatic and represent an obvious departure from the long-term
patterns," AMAP said.

"The changes that are emerging in the Arctic are very strong, dramatic even," said Mark Serreze, director of the US National Snow and Ice Data Center in Boulder, Colorado, and a contributor to the report.

"But this is not entirely a surprise. We have known for decades that, as climate change takes hold, it is the Arctic where you are going to see it first, and where it is going to be pronounced," he said by phone.

Some Antarctic Ice Forms From the Bottom Up

Khaleej News (Reuters)

4 March 2011

OSLO - Some of Antarctica’s ice sheet is formed by water re-freezing from below not just by snow falling on top as was traditionally thought, findings showed on Thursday that will help scientists project effects of climate change.

Experts are seeking to understand the frozen continent since even a small thaw could swamp low-lying coastal areas and cities. Antarctica contains enough ice to raise world sea levels by about 57 metres (187 ft) if it ever all melted.

A six-nation study of the jagged mountain range as high as the Alps that is buried under ice in East Antarctica found that almost a quarter of the ice sheet in the area was formed by a thaw and re-freeze of water from underneath.

Deep below the surface, ice flowing into narrow, submerged valleys often melted because of high pressure and heat from the earth below and re-froze when it was forced up again.

The findings, published in the journal Science, confound a traditional view that ice sheets are almost solely formed by snow that lands on top, gets compressed into ice and flows slowly towards the oceans because of gravity.

“We usually think of ice sheets like cakes — one layer at a time added from the top. This is like someone injected a layer of frosting at the bottom — a really thick layer,” Robin Bell, lead author at Columbia University in New York, said in a statement.

Dome

The scientists said that about 24 percent of the ice in an area around Dome A, a 13,800 feet (4,206 metres) high plateau the size of California that forms the top of East Antarctica, was formed by re-frozen ice.

“In some places up to half the ice thickness has been added from below,” they wrote of ice above the invisible Gamburtsev Mountain range.

The finding could help understand flows of Antarctic and Greenland ice sheets, and possible responses to global warming.

The British Antarctic Survey (BAS), which took part, said it gave “new understanding about ice sheet growth and movement that is essential for predicting how the ice sheet may change as the Earth’s climate warms.”

Radars spotted unexpected bulges deep in the ice — one was 1 km (0.6 mile) high from the bottom of the ice sheet. “We almost thought the equipment was broken,” co-author Tom Jordan of BAS told Reuters.

The U.N. panel of climate scientists projected in a 2007 report that world sea levels may rise by 18-59 cm (7-24 inches) in the 21^st century, or by more if a thaw of Greenland or Antarctica picks up.

The thaw and re-freeze might also affect chances of finding unknown life in sub-glacial lakes in Antarctica such as Vostok where Russian scientists have been drilling. These lakes may have been isolated for a shorter time than previously believed.

Antarctica’s ice sheet formed about 32 million years ago but Jordan said that experts now believed the oldest ice was only 1.4 million years old.

World's Sixth Mass Extinction May Be Underway - Study

Yahoo News
March 3, 2011

Mankind may have unleashed the sixth known mass extinction in Earth's history, according to a paper released on Wednesday by the science journal Nature.

Over the past 540 million years, five mega-wipeouts of species have occurred through naturally-induced events.

But the new threat is man-made, inflicted by habitation loss, over-hunting, over-fishing, the spread of germs and viruses and introduced species, and by climate change caused by fossil-fuel greenhouse gases, says the study.

Evidence from fossils suggests that in the "Big Five" extinctions, at least 75 percent of all animal species were destroyed.

Palaeobiologists at the University of California at Berkeley looked at the state of biodiversity today, using the world's mammal species as a barometer.

Until mankind's big expansion some 500 years ago, mammal extinctions were very rare: on average, just two species died out every million years.

But in the last five centuries, at least 80 out of 5,570 mammal species have bitten the dust, providing a clear warning of the peril to biodiversity.

"It looks like modern extinction rates resemble mass extinction rates, even after setting a high bar for defining 'mass extinction," said researcher Anthony Barnosky.

This picture is supported by the outlook for mammals in the "critically endangered" and "currently threatened" categories of the Red List of biodiversity compiled by the International Union for Conservation of Nature (IUCN).

On the assumption that these species are wiped out and biodiversity loss continues unchecked, "the sixth mass extinction could arrive within as little as three to 22 centuries," said Barnosky.

Compared with nearly all the previous extinctions this would be fast-track.

Four of the "Big Five" events unfolded on scales estimated at hundreds of thousands to millions of years, inflicted in the main by naturally-caused global warming or cooling.

The most abrupt extinction came at the end of the Cretaceous, some 65 million years ago when a comet or asteroid slammed into the Yucatan peninsula, in modern-day Mexico, causing firestorms whose dust cooled the planet.

An estimated 76 percent of species were killed, including the dinosaurs.

The authors admitted to weaknesses in the study. They acknowledged that the fossil record is far from complete, that mammals provide an imperfect benchmark of Earth's biodiversity and further work is needed to confirm their suspicions.

But they described their estimates as conservative and warned a large-scale extinction would have an impact on a timescale beyond human imagining.

"Recovery of biodiversity will not occur on any timeframe meaningful to people," said the study.

"Evolution of new species typically takes at least hundreds of thousands of years, and recovery from mass extinction episodes probably occurs on timescales encompassing millions of years."

Even so, they stressed, there is room for hope.

"So far, only one to two percent of all species have gone gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction. We still have a lot of Earth's biota to save," Barnosky said.

Even so, "it's very important to devote resources and legislation toward species conservation if we don't want to be the species whose activity caused a mass extinction."

Asked for an independent comment, French biologist Gilles Boeuf, president of the Museum of Natural History in Paris, said the question of a new extinction was first raised in 2002.

So far, scientists have identified 1.9 million species, and between 16,000 and 18,000 new ones, essentially microscopic, are documented each year.

"At this rate, it will take us a thousand years to record all of Earth's biodiversity, which is probably between 15 and 30 million species" said Boeuf.

"But at the rate things are going, by the end of this century, we may well have wiped out half of them, especially in tropical forests and coral reefs."

Catastrophic Drought in the Amazon

The Independent

February 3, 2011

A widespread drought in the Amazon rainforest last year caused the "lungs of the world" to produce more carbon dioxide than they absorbed, potentially leading to a dangerous acceleration of global warming. Scientists have calculated that the 2010 drought was more intense than the "one-in-100-year" drought of 2005.

They are predicting it will result in some eight billion tonnes of carbon dioxide being expelled from the Amazon rainforest, which is more than the total annual carbon emissions of the United States. For the second time in less than a decade, the earth's greatest rainforest released more carbon dioxide than it absorbed because many of its trees dried out and died.

Scientists believe that the highly unusual nature of the two droughts, which occurred in the space of just five years, may be the result of higher sea-surface temperatures in the tropical Atlantic, which could also be influenced by global warming caused by the release of man-made emissions of carbon dioxide and other greenhouse gases. The Anglo-Brazilian team of researchers has emphasised that there is as yet no proof that the two highly unusual droughts in the Amazon are the direct result of rising carbon dioxide levels in the atmosphere, but the scientists have warned that the world is gambling with its future if it fails to curb fossil fuel emissions.

Simon Lewis of Leeds University, the lead author of the study, said: "If greenhouse gas emissions contribute to Amazon droughts that in turn cause forests to release carbon, this feedback loop would be extremely concerning. Put more starkly, current emissions pathways risk playing Russian roulette with the world's largest rainforest.

"Two unusual and extreme droughts occurring within a decade may largely offset the carbon absorbed by intact Amazon forests during that time. If events like this happen more often, the Amazon rainforest would reach a point where it shifts from being a valuable carbon sink slowing climate change to a major source of greenhouse gases that could speed it up. Having two events of this magnitude in such close succession is extremely unusual, but is unfortunately consistent with those climate models that project a grim future for Amazonia."

The study, published in the journal Science, analysed satellite data on rainfall across two million square miles of rainforest during the 2010 dry season. The scientists were able to make a direct comparison with an earlier study of the 2005 drought, which also looked at the effect of the low rainfall on the growth of trees.

In the 2005 drought, the scientists estimated that the rainforest turned from a net absorber of about two billion tonnes of carbon dioxide to an exporter of some five billion tonnes of carbon dioxide, which is almost as much as the 5.4 billion tonnes emitted annually by the US.

However, the drought last year was more widespread and more intense than the earlier drought, with a far bigger impact on the growth and death of trees, which is why the scientists expect the overall release of carbon dioxide from dead and decaying organic matter to reach eight billion tonnes.

"The extent of the 2010 drought was much larger than in 2005. In 2010, the Rio Negro river, which is the biggest tributary to the Amazon, was at its lowest level since records began at the start of the 20th century, so we have independent evidence of these droughts," Dr Lewis said.

Normally, the cycle of droughts that hit the Amazon affect northern areas of the region and are associated with the natural el Niño phenomenon in the Pacific Ocean. However, the 2005 and 2010 droughts occurred further south and may be linked with higher sea-surface temperatures in the tropical Atlantic Ocean, the scientists said.

"In 2005, the spatial pattern of the drought affecting the south and southwest of the Amazon was very different from the usual droughts that impact the Amazon every five to seven years associated with el Niño events, which tend to affect the north-east. When climatologists investigated why, they associated it with Atlantic sea-surface temperatures," Dr Lewis said.

"In 2010 we see a drought with a very similar spatial pattern, again affecting the south and the south-west of the Amazon basin, and very similar to 2005, and we know that the Atlantic sea-surface temperatures were anomalously high, but the work has not been done yet to say definitively that that is the cause. Our best hypothesis at the present time is that this 2010 drought was associated with Atlantic sea-surface temperatures, but we have to wait until those scientific papers go through the peer-review process before we can say that more concretely."

Peter Cox, of Exeter University, who analysed the 2005 drought, said: "The droughts in Amazonia in 2005 and 2010 were both associated with unusually warm ocean temperatures in the tropical North Atlantic. This tends to draw the region of most intense rainfall further north and delays the wet season in Amazonia."