Oceans could rise 1.6 metres by 2100: study

Marlowe Hood Yahoo News 3 May 11;

PARIS (AFP) – Warming in the Arctic occurring at twice the global average is on track to lift sea levels by up to 1.6 metres (5.3 feet) by 2100, a far steeper jump than predicted a few years ago, a consortium of scientists reported Tuesday.

Melting ice and snow has accounted for 40 percent of recent increases in ocean levels and are likely to play an even larger role in future, according to the Oslo-based Arctic Monitoring and Assessment Project (AMAP).

"Global sea level is projected to rise 0.9 to 1.6 metres (3.0 to 5.3 feet) by 2100, and the loss from Arctic glaciers, ice caps and the Greenland Ice Sheet will make a substantial contribution to this," AMAP said in a report.

Even the low end of this range would have devastating consequences for coastal cities and densely-populated, low-lying deltas in Bangladesh, Vietnam, China and many other countries, scientists have warned.

Higher seas would literally cover some small island nations, ruin vast expanses of land used to grow food, and boost the intensity of deadly hurricanes and other extreme weather events.

In early 2007, the UN's Intergovernmental Panel on Climate Change (IPCC) said the world's oceans would creep up 18 to 59 centimetres (7 to 23 inches) by century's end.

But the panel's landmark report did not include the potential impact of melting ice, especially from the massive Greenland Ice Sheet, which alone holds enough frozen water to push up sea levels by at least five metres (16 feet).

The new study shows that the past six years have been the warmest period ever recorded for the Arctic, and that summer temperatures were higher in the past few decades than at any time in the last 2,000 years.

"The changes that are emerging in the Arctic are very strong, dramatic even," said Mark Serreze, director of the U.S. 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.

The report forecasts that the Arctic Ocean, within three or four decades, will likely become nearly ice free during the summer months.

Three of the last four years have seen polar sea ice shrinking to its smallest area since satellite images became available, with a record low in 2007 of 4.13 million square kilometres (1.56 million square miles).

The report also highlights new evidence that changes in Arctic snow and ice conditions may actually be accelerating the warming process.

"The fact that highly reflective snow and ice surfaces are diminishing means that darker land or ocean surfaces are absorbing more of the sun's energy, warming the Earth's surface and the air above," the researchers said.

Rather than being bounced back into space by white surfaces, in other words, the sun's heat is trapped inside the atmosphere.

The study identified eight of these so-called natural "feedback mechanisms" that have become both symptom and cause of climate change.

Rising average temperatures, for example, threaten to unlock long-frozen stores of carbon dioxide and methane -- at least 20 times as potent a greenhouse gas as CO2 -- from the region's permafrost.

"The amount of carbon that is locked up in permafrost is equivalent to what is in the atmosphere today," said Serreze. "The question is how much of it is going be released."

Drawing from the research of several hundred climate scientists and glaciologists, the report comes ahead of a May 12 meeting in Greenland of foreign ministers from Arctic Council nations: Canada, Denmark, Finland, Iceland, Norway, Russia, Sweden and the United States.

Founded in 1991, AMAP is now a working group of the Council.

Report sees sharper sea rise from Arctic melt
Karl Ritter and Charles J. Hanley, Associated Press Yahoo News 5 May 11;

STOCKHOLM – The ice of Greenland and the rest of the Arctic is melting faster than expected and could help raise global sea levels by as much as 5 feet this century, dramatically higher than earlier projections, an authoritative international assessment says.

The findings "emphasize the need for greater urgency" in combating global warming, says the report of the Arctic Monitoring and Assessment Program (AMAP), the scientific arm of the eight-nation Arctic Council.

The warning of much higher seas comes as the world's nations remain bogged down in their two-decade-long talks on reducing emissions of carbon dioxide and other greenhouse gases blamed for global warming.

Rising sea levels are expected to cause some of global warming's worst damage — from inundated small islands to possible flooding of New York City's subways. Oceans will not rise uniformly worldwide, because of currents, winds and other factors, but such low-lying areas as Bangladesh and Florida will likely be hard-hit.

The new report, whose executive summary was obtained by The Associated Press, is to be delivered to U.S. Secretary of State Hillary Rodham Clinton and foreign ministers of the other seven member nations at an Arctic Council meeting next week in Greenland. It first will be discussed by some 400 international scientists at a conference this week in Copenhagen, Denmark.

Drawing on improved research techniques and recent scientific papers, the AMAP report updates forecasts made by the U.N.'s expert panel on climate change in its last major assessment in 2007.

The melting of Arctic glaciers and ice caps, including Greenland's massive ice sheet, is projected to help raise global sea levels by 35 to 63 inches (90 to 160 centimeters) by 2100, AMAP said, although it noted that estimate was highly uncertain.

That's up from the 2007 projection of 7 to 23 inches (19 to 59 centimeters) by the U.N. panel. The U.N. group had left out the possible acceleration of melting in Greenland and Antarctica, saying research on that hadn't advanced sufficiently by the mid-2000s. The U.N. estimate was based largely on the expansion of ocean waters from warming and the runoff from melting land glaciers elsewhere in the world.

Now the AMAP assessment finds that Greenland was losing ice in the 2004-2009 period four times faster than in 1995-2000.

In addition, the cover of sea ice on the Arctic Ocean is shrinking faster than projected by the U.N. panel, threatening the long-term survival of polar bears and other ice-dependent species. Summer ice coverage has been at or near record lows every year since 2001, said AMAP, predicting the ocean will be almost ice-free in the summer in 30 to 40 years.

Arctic temperatures in the past six years were the highest since measurements began in 1880, and "feedback" mechanisms are believed to be speeding up warming in the far north.

One such mechanism involves the ocean absorbing more heat when it's not covered by ice, because ice reflects the sun's energy. That effect has been anticipated by scientists "but clear evidence for it has only been observed in the Arctic in the past five years," AMAP said.

It projected that average fall and winter temperatures in the Arctic will climb by roughly 5 to 11 degrees Fahrenheit 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.

A leading American ice specialist, Richard Alley of Pennsylvania State University, who did not take part in the AMAP assessment, agreed that recent scientific estimates generally support its central finding.

A sea level rise of more than 3 feet this century "fits well within these estimates, and a somewhat higher value cannot be excluded," Alley said.

Scientists have steadily improved ways of measuring the loss of ice into the oceans.

In research reported in March in the journal Geophysical Research Letters, U.S. and European scientists used two independent methods to corroborate their findings: the on-the-ground measurement of ice thickness and movements using GPS stations and other tools, and the measurement of ice mass through gravity readings from satellites.

Led by Eric Rignot of NASA's Jet Propulsion Laboratory, they calculated that the accelerating melt of the vast Greenland and Antarctic ice sheets would contribute to an overall sea-level rise of some 13 inches by 2050. They didn't project sea levels to 2100 because of long-range uncertainties, but their work, like AMAP's, significantly updates previous projections.

The AMAP report said melting glaciers and ice sheets worldwide have become the biggest contributor to sea level rise. Greenland's ice sheet alone accounted for more than 40 percent of the 0.12 inches (3.1 millimeters) of sea-level rise observed annually between 2003 and 2008, AMAP said.

The AMAP group's main function is to advise the nations surrounding the Arctic — the U.S., Canada, Russia, Denmark, Norway, Sweden, Iceland and Finland — on threats to its environment.

The updated projections should supply further scientific ammunition in the uphill struggle for concerted global action to rein in greenhouse emissions. The failure of emissions-capping legislation in the U.S. Congress last year was one major setback.

"I'm not sure what is more alarming, the glacial pace of Congress to reduce carbon pollution or the astounding rate of melting Arctic ice," Lou Leonard, climate chief at the World Wildlife Fund, said of the new report.

___

Hanley reported from New York.


Seas Could Rise Up To 1.6 Meters By 2100: Study
Alister Doyle & Pete Harrison Reuters 4 May 11;

Quickening climate change in the Arctic including a thaw of Greenland's ice could raise world sea levels by up to 1.6 meters by 2100, an international report showed on Tuesday.

Such a rise -- above most past scientific estimates -- would add to threats to coasts from Bangladesh to Florida, low-lying Pacific islands and cities from London to Shanghai. It would also, for instance, raise costs of building tsunami barriers in Japan.

"The past six years (until 2010) have been the warmest period ever recorded in the Arctic," according to the Oslo-based Arctic Monitoring and Assessment Programme (AMAP), which is backed by the eight-nation Arctic Council.

"In the future, global sea level is projected to rise by 0.9 meters (2ft 11in) to 1.6 meters (5ft 3in) by 2100 and the loss of ice from Arctic glaciers, ice caps and the Greenland ice sheet will make a substantial contribution," it said. The rises were projected from 1990 levels.

"Arctic glaciers, ice caps and the Greenland ice sheet contributed over 40 percent of the global sea level rise of around 3 mm per year observed between 2003 and 2008," it said.

Foreign ministers from Arctic Council nations -- the United States, Russia, Canada, Sweden, Finland, Denmark, Norway and Iceland -- are due to meet in Greenland on May 12. Warming in the Arctic is happening at about twice the world average.

WORRYING

The United Nations' Intergovernmental Panel on Climate Change (IPCC) said in its last major report in 2007 that world sea levels were likely to rise by between 18 and 59 cm by 2100. Those numbers did not include a possible acceleration of a thaw in polar regions.

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

"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.

U.N. talks on a global pact to combat climate change are making sluggish progress. The United Nations says national promises to limit greenhouse gas emissions, mainly from burning fossil fuels, are insufficient to avoid dangerous changes.

The AMAP study, drawing on work by hundreds of experts, said there were signs that warming was accelerating. It said the Arctic Ocean could be nearly ice free in summers within 30 to 40 years, earlier than projected by the IPCC.

As reflective ice and snow shrink, they expose ever bigger areas of darker water or soil. Those dark regions soak up ever more heat from the sun, in turn stoking a melt of the remaining ice and snow.

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

The AMAP report was due for release on Wednesday but AMAP officials released it a day early after advance media leaks.

(Editing by Janet Lawrence)

FACTBOX-Arctic experts warn of higher sea level rise
Reuters AlertNet 3 May 11;

May 3 (Reuters) - World sea levels could rise by between 0.9 and 1.6 metres (2ft 11in to 5ft 3in) this century, stoked by accelerated climate change in the Arctic, a study showed on Tuesday. [ID:nLDE7421AX]

The projection, by the Arctic Monitoring and Assessment Programme, is higher than most past estimates including a 2007 report by the Intergovernmental Panel on Climate Change (IPCC), the main U.N. scientific group.

Rising sea levels are a threat to cities from New York to Buenos Aires, coasts from the Netherlands to China and low-lying islands in the Pacific or Indian Oceans.

Following is a history of sea level rise and projections:

HISTORY - Sea levels rose about 120 metres (almost 400 ft) after a thaw at the end of the last Ice Age about 21,000 years ago released vast amounts of water frozen on land.

Sea levels stabilised about 2,000 to 3,000 years ago, with "no significant change from then until the late 19th century", the IPCC said in 2007. During the 20th century, they rose about 17 cms. Since 1993, rates have accelerated to about 3 mm per year.

RECENT ESTIMATES

May 2011 - "Global sea level is projected to rise by 0.9 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," according to a report overseen by the AMAP, part of the eight-nation Arctic Council.

Sept. 2009 - U.N. Secretary-General Ban Ki-moon said "by the end of this century, sea levels may rise between half a metre and two metres".

March 2009 - Sea-level rise may well exceed one metre by 2100, according to a group of leading scientists meeting in Copenhagen and updating IPCC findings from 2007.

Feb. 2007 - The IPCC said sea levels could rise by between 18 and 59 cms by 2100. Another 10 to 20 cms could be added if flows of Greenland and West Antarctic ice accelerated in line with rising temperatures. It also said sea level rise would continue for centuries.

2001 - Sea levels could rise by between 9 and 88 cms by 2100, with a central estimate of 48 cms, according to the IPCC.

1995 - Sea levels could increase by between 13 and 94 cms by 2100, according to the IPCC.

1990 - The IPCC said seas could rise by between 31 and 110 cms under "business as usual policies" this century, ie without action to combat global warming.

SOURCES OF MELT

In 2007, the IPCC said the biggest contributor to sea level rise would be thermal expansion -- water increases in volume as it warms. It said thermal expansion would contribute about 70 to 75 percent to sea level rise this century.

Glaciers from the Andes to the Alps, ice caps and Greenland were also expected to contribute water. Most of Antarctica is too cold to melt and was expected to get more snow, meaning it will take water from the oceans, the IPCC said.

ICE SHEETS

Antarctica contains enough ice to raise sea levels by about 57 metres if it ever all melted. Worries include that a collapse of ice shelves around the coast may allow inland ice to slide faster towards the ocean. Greenland's ice would raise sea levels by 7 metres if it all vanished. (Editing by Janet Lawrence) (For Reuters latest environment blogs, click on: http://blogs.reuters.com/environment/)