NASA via Reuters, file

The Sheldon Glacier with Mount Barre in the background, is seen from Ryder Bay near Rothera Research Station, Adelaide Island, Antarctica, in this NASA handout photo.

OSLO, Norway - Global warming is expanding the extent of sea ice around Antarctica in winter in a paradoxical shift caused by cold plumes of summer melt water that re-freeze fast when temperatures drop, according to a study unveiled Sunday.

An increasing summer thaw of ice on the edges of Antarctica, twinned with less than expected snowfall on the frozen continent, is also adding slightly to sea level rise in a threat to low-lying areas around the world, it said.

Climate scientists have been struggling to explain why sea ice around Antarctica has been growing, reaching a record extent in the winter of 2010, when ice on the Arctic Ocean at the other end of the planet shrank to a record low in 2012.

Sinead Farrell / NASA

Ice floes are shown at the foot of an iceberg in Antarctica's Amundsen Sea in October 2010.

"Sea ice around Antarctica is increasing despite the warming global climate," said Richard Bintanja, lead author of the study at the Royal Netherlands Meteorological Institute.

"This is caused by melting of the ice sheets from below," he told Reuters of the findings in the journal Nature Geoscience.

Ice is made of fresh water and, when ice shelves on the fringes of Antarctica thaw in summer because of upwellings of warming sea water, the meltwater forms a cool layer that floats on the denser, warmer salty sea water below, the study said.

In winter, the melt water readily turns to ice because it freezes at zero degrees Celsius, above sea water at -2C (28.4F).

At a winter maximum in September, ice on the sea around Antarctica covers about 19 million sq kms (7.3 million sq miles), bigger than Antarctica's land area. It then melts away into the ocean as summer approaches.

Among other scientists, Paul Holland of the British Antarctic Survey stuck to his findings last year that a shift in winds linked to climate change was blowing a layer of melt water further out to sea and adding to winter ice.

"The possibility remains that the real increase is the sum of wind-driven and melt water-driven effects, of course. That would be my best guess, with the melt water effect being the smaller of the two," he said.

Bintanja's study also said the cool melt water layer may limit the amount of water sucked from the oceans that falls as snow on Antarctica. Cold air can hold less moisture than warm.

"Cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise," it said.

The U.N. panel of climate scientists has estimated that sea levels will rise by between 18 and 59 cm (7-24 inches) this century, more if thaws of Antarctica and Greenland accelerate.

The panel's main scenarios assume that Antarctica alone will make sea levels fall by between 2 and 14 cms this century because more snowfall will extract water from the sea.

But Sunday's study said that Antarctica was losing about 250 billion tonnes of ice a year - equivalent to 0.07 millimetre(0.003 inch) of sea level rise a year, Bintanja said. "Antarctic mass loss seems to be accelerating," it said.

Another study in Nature Geoscience said Antarctica's snowfall had been over-estimated by between 11 and 36.5 billion tonnes a year because of fierce winds blasting many regions.

Strong winds created conditions to "sublimate" snow, or make it pass from a frozen state to a gas without first becoming liquid, a U.S.-led team wrote. 

Alistair Scrutton / Reuters

Kim Ernst, the Danish chef of Roklubben restaurant, which is nestled by a frozen lake near a former Cold War-era U.S. military base, looks over his greenhouse in Kangerlussaq on March 5, 2013.

KANGERLUSSUAQ, Greenland — On the Arctic Circle, a chef is growing the kind of vegetables and herbs - potatoes, thyme, tomatoes, green peppers - more fitting for a suburban garden in a temperate zone than a land of Northern Lights, glaciers and musk oxen.

Some Inuit hunters are finding reindeer fatter than ever thanks to more grazing on this frozen tundra, and for some, there is no longer a need to trek hours to find wild herbs.

Welcome to climate change in Greenland, where locals say longer and warmer summers mean the country can grow the kind of crops unheard of years ago.

"Things are just growing quicker," said Kim Ernst, the Danish chef of Roklubben restaurant, nestled by a frozen lake near a former Cold War-era U.S. military base.

"Every year we try new things," said Ernst, who even managed to grow a handful of strawberries that he served to some surprised Scandinavian royals. "I first came here in 1999 and no-one would have dreamed of doing this. But now the summer days seem warmer, and longer."

It was minus 20 degrees Centigrade in March but the sun was out and the air was still, with an almost spring feel. Ernst showed his greenhouse and an outdoor winter garden which in a few months may sprout again.

Hundreds of miles south, some farmers now produce hay, and sheep farms have increased in size. Some supermarkets in the capital Nuuk sell locally grown vegetables during the summer.

Major commercial crop production is still in its infancy. But it is a sign of changes here that Greenland's government set up a commission this year to study how a changing climate may help farmers increase agricultural production and replace expensive imported foods.

Change is already under way. Potatoes grown commercially in southern Greenland reached over 100 tons in 2012, double that of 2008. Vegetable production in the region may double this year compared with 2012, according to government data.

Some politicians hope global warming will allow this country a quarter the size of the United States to reduce its dependency on former colonial master Denmark for much of its food as political parties push for full independence.

Greenland, which is self-governing aside from defense and security, depends on an annual grant from Denmark of around $600 million, or half the island's annual budget. But the thawing of its enormous ice sheets have seen a boost in mining and oil exploration, as well as an interest in agriculture.

"I expect a lot of development in farming sheep and agriculture due to global warming," said Prime Minister Kuupik Kleist, whose government set up the commission. "It may become an important supplement to our economy."

Locals love recounting how Erik the Red first arrived in the southern fjords here in the 10th century and labeled this ice-covered island "Greenland" to entice others to settle. There is evidence that the climate was warmer then, allowing Viking settlements to grow crops for five centuries before mysteriously dying out.

From cows to crops
The scale of this new agriculture is tiny. There are just a few dozen sheep farms in southern Greenland, where most of the impact of climate change can be seen. Cows may number less than a hundred. But with 57,000 mostly Inuit human inhabitants, the numbers to feed are also small.

"You need to put this into perspective. We used to be high Arctic and now we are more sub Arctic," Kenneth Hoegh, an agronomist and former senior government adviser. "But we are still Arctic."

The symbolism is enormous, however, highlighting a changing global climate that has seen temperatures in the Arctic increase by about twice the global average - about 0.8 degrees Celsius since pre-industrial times.

"There are now huge areas in southern Greenland where you can grow things," said Josephine Nymand, a scientist at the Greenland Institute of Natural Resources in Nuuk. "Potatoes have most benefited. Also, cabbage has been very successful."

Sten Erik Langstrup Pedersen, who runs an organic farm in a fjord near Nuuk, first grew potatoes in 1976. Now he can plant crops two weeks earlier in May and harvest three weeks later in October compared with more than a decade ago.

He grows 23 kinds of vegetables, compared with 15 a decade ago, including beans, peas, herbs and strawberries. He says he has sold some strawberries to top restaurants in Copenhagen.

But Pedersen is skeptical about how much it will catch on.

"Greenlanders are impatient. They see a seal and they immediately just want to hunt it. They can never wait for vegetables to grow."

There is still potential. Hoegh estimates Greenland could provide half its food needs from home-grown produce which would be competitive with more expensive Danish imports.

But global change is not all about benefits. While summers are warmer, there is less rain. Some experts say that Greenland could soon need irrigation works - ironic for a country of ice and lakes.

"We have had dry summers for the last few years." said Aqqalooraq Frederiksen, a senior agricultural consultant in south Greenland, who said a late spring last year hurt potato crops.

On the Arctic circle, a flash flood last summer from suspected glacier melt water - which some locals here blamed on warm weather - swept away the only bridge connecting Ernst's restaurant to the airport. It came right in the middle of the tourist season, and the restaurant lost thousands of dollars.

It was an ominous reminder that global warming will bring its problems. Still, for Pedersen and his fjord in Nuuk, the future looks good.

"The hotter, the better," Pedersen said. "For me."

NBC News Correspondent Kerry Sanders recently returned from Antarctica, where he chronicled the dramatic changes in the world's last wilderness. Below is his main report; you also can click on the map above for more dispatches from across the breathtaking seventh continent.

By Kerry Sanders, Correspondent, NBC News

ANTARCTIC PENINSULA — There are serious changes taking place here at the bottom of the world.

Increasingly, experts say, the ice is disappearing at a disturbing rate in the Antarctic Peninsula and that in turn impacts the future -- and perhaps the very existence — of at least half of the world’s 18 penguin species, who depend on ice and frigid waters that support krill, the penguin diet mainstay.

"When cheetahs or lions get hunted, or elephants decline, there’s a big uproar. And I think, because you see penguins in large numbers [in some places] people are ignoring the larger rate of their decline," said Oxford University penguinologist Tom Hart. "The general public doesn't realize the penguins are declining so fast."

But it’s not just the penguins we have to worry about, Hart says, it’s the health of the planet itself.

"The last wilderness on Earth is impacted by us now," he said, describing the region’s decline as a "grave indicator" of what’s to come.

Life’s cycle disrupted for Antarctica’s penguins
It’s the end of the breeding cycle for most penguins here as summer comes to a close. The Gentoos, Adelies and Chinstraps are nudging their newborns from the rocks of Antarctica’s peninsula toward the waters of the Southern Ocean.

Experts say about 50 percent of the eggs will produce a penguin chick that makes it to sea. And about half of those will survive the hungry predators below, as they plunge into the frigid waters for their first swim. Leopard seals are lurking -- and for the newborns, avoiding their mortal enemy is not easy. Many will die. Those that do survive are subject to climate change that is threatening their food supply.

Hart has spent nearly a decade studying the creatures that have captured the world’s imagination for centuries. Each year, for three to four months, he positions himself along the Antarctic coast to observe, measure and chart penguin colonies. Some colonies have been followed since polar explorer Sir Ernest Shackleton and his men headed here some 100 years ago.

"When you look at all penguins they are largely in trouble," said Hart. "We're so concerned because we're seeing massive changes to their populations. They’re probably not going to go extinct anytime soon, but the environment is changing very fast.

Chinstraps populations seem to have declined up to 50 percent in the last 30 years," he added.

Hart, like most experts, is cautious to speak in absolutes because the harsh environment here makes it difficult to get a clear picture of what’s happening.  Experts use time-lapse cameras and sit at computers, laboriously counting penguins one by one to compare colony sizes from year to year.

Krill decline quickly as sea ice disappears
Ice is the source of all life in Antarctica.  It may seem at odds to think that ice gives life, but when you connect the dots, it’s a straight line to a penguin’s belly.

Algae live on top of the ice and underneath it too, providing a grazing ground for the krill that amass beneath -- the way a raccoon chooses to hide in a garbage can. 

Krill mostly stay put under the frozen Southern Ocean.  But as the ice sheet disappears due to climate change, that habitat shrinks and moves further south. 

"The West Antarctic Peninsula has increased three degrees since 1951,” Hart said. "We’ve seen a large reduction in sea ice over the same period."

Although the climate has always undergone oscillations in temperature, Hart says the recent changes are happening much faster than normal.

Logically, less ice has resulted in less krill, say marine biologists.  And since krill is the main diet for penguins, seals and whales, less food has in turn meant fewer births.  That theory is widely accepted by scientists like French marine biologist Fabrice Genevois.

He says it’s mostly Americans, who have confused politics with science by questioning global climate change.

"We have all the information now, that's clear enough,” said Genevois. "There's no argument any more. You have to be either a liar or be crazy not to understand what we are doing to change the climate. We are responsible, that's for sure."

Add to that equation: Fishing. Less ice has opened areas to more fishing boats that in turn have targeted krill as a profitable catch.

There’s a 620,000 ton catch limit for krill in Antarctica, which is only about 1 percent of the total estimated mass in the region.

But it’s the location of the krill fisheries — all aggregated in the Antarctic Peninsula near the South Shetland Islands — that is the main cause of concern.

The boats increasingly drop their nets in the same waters where penguins search for food. The nets are not catching penguins indiscriminately but they are competing for the krill that the wildlife eats to survive.

Where do those captured krill end up? In part, they’re used as fish food at salmon farms, desirable because krill help color salmon “pink” which increases sales at the supermarket.

Click here and here for more on managing the krill catch.

Slideshow: Antarctica: Journey to the bottom of the Earth

/

See photos from NBC's Kerry Sanders' voyage to Antarctica.

Launch slideshow

Canary in a coal mine
The entire population of Emperor penguins, Chinstraps and Adelies live in Antarctica — if the ice continues to retreat those species are at risk. Meanwhile, the potential for disease outbreaks increases.  

"As regions of Antarctica warm it has much more potential as a petri dish," said Hart, citing disease from the north, in particular avian disease, as being a main concern. 

The penguins, marine biologists say, are giving us a warning. 

"We don't need to necessarily fear change," said marine biologist Maria Clauss, who works with tour company Quark Expeditions. But the penguin’s decline "will change the world as we know it," she said. "And we should not kid ourselves."

Day 1: Greeted by dirt, not ice

Day 2: Climate change decimates food supply for penguins

Day 3: Watching Mother Nature in action

Day 4: How to sleep outdoors in Antarctica

Finale: Trips to the seventh continent are not just for scientists

Laurent Gillieron / EPA

A worker makes the last preparations Monday before the opening of the 43rd Annual Meeting of the World Economic Forum in Davos, Switzerland, where Ban Ki-moon, other world leaders and business people will meet.

UNITED NATIONS — U.N. Secretary-General Ban Ki-moon says his top hopes for 2013 are to reach a new agreement on climate change and to urgently end the increasingly deadly and divisive war in Syria.

The U.N. chief told The Associated Press that he's also hoping for progress in getting the global economy humming again, restarting Israeli-Palestinian peace negotiations, promoting political solutions in Mali, Congo and the Central African Republic, and providing energy, food and water to all people.

Ban laid out this ambitious wish list in an interview before heading to the World Economic Forum in Davos this week, saying he plans to take "the uncommon opportunity" of being with some 2,500 government, business and civil society leaders in the Swiss ski resort to exchange frank views on these issues.

"The world is now experiencing unprecedented challenges," Ban said.

"Climate change is fast happening — much, much faster than one would have expected," he said. "Climate and ecosystems are under growing strain."

Ban spoke before President Barack Obama, in his inaugural address Monday, put a similar emphasis on tackling climate change in his second term.

'Mobilize the political will'
Two-decade-old U.N. climate talks have so-far failed in their goal of reducing the carbon dioxide and other greenhouse gas emissions that a vast majority of scientists says are warming the planet.

In December, a U.N. climate conference in Doha, Qatar, agreed to extend the Kyoto Protocol, a treaty that limits the greenhouse gas output of some rich countries, and affirmed a previous decision to adopt a new global climate pact by 2015.

"I will do my best to mobilize the political will and resources so that the member states can agree to a new legally binding global agreement on climate change," Ban said.

Ban urged progress in getting nations and people to use the world's limited resources without waste and in ways to ensure their replacement, so that all people will have enough to eat and drink and there will be electricity for their homes — and have energy to spare to promote economic growth.

"We have to have sustainable development," he said. "That's our number one priority together with climate change."

Momentum for fighting climate change has stalled amid recessions, financial meltdown and government debt crises of the past five years.

"At the same time, we need to see some economic dynamism," Ban said. "The world is still suffering, struggling to overcome its economic crisis."

The forum at Davos, opening Wednesday, focuses this year on how to ensure a more sturdy economic recovery that can withstand the kind of shocks the past few years have wrought.

Among the world leaders he may rub elbows with at Davos are Microsoft founder Bill Gates, International Monetary Fund Managing Director Christine Lagarde and German Chancellor Angela Merkel.

The secretary-general expressed hope that the major powers will be able to revitalize growth, which will help developing countries meet the U.N. Millennium Development Goals to combat poverty by the target date of 2015.

The goals include cutting extreme poverty by half, ensuring a primary school education for every child, reducing maternal and infant mortality, and halting and reversing the HIV/AIDS pandemic.

On the political front, Ban said he is deeply concerned about the deteriorating situation in Syria where the conflict will soon be entering its third year.

"I believe that world leaders must address this issue with a top priority and a sense of urgency. We cannot go on like this," he said. "More than 60,000 people have been killed, and if the situation continues like this way, we will have to see more and more death, more and more people who are fleeing Syria."

The secretary-general said he is also mobilizing U.N. envoys and others to try to make progress on the Mideast peace process; in Mali, where a French-led military operation is fighting Islamist extremists; the deteriorating political situation in Congo where M23 rebels have gained ground; and in the Central African Republic where rebels recently signed a peace agreement with the president.

Related content:

Climate talks end with deal that's 'not where we wanted to be'

Kremlin begins evacuation of Russians from Syria

Insurgents abandon towns in central Mali as French troops advance

Alister Doyle / Reuters file

Climate change is turning Antarctica's ice into one of the biggest risks for coming centuries, scientists say.

West Antarctica is warming almost twice as fast as previously believed, adding to worries of a thaw that would add to sea level rise from San Francisco to Shanghai, a study showed on Sunday. 

Annual average temperatures at the Byrd research station in West Antarctica had risen 2.4 degrees Celsius (4.3 Farenheit) since the 1950s, one of the fastest gains on the planet and three times the global average in a changing climate, it said. 

The unexpectedly big increase adds to fears the ice sheet is vulnerable to thawing. West Antarctica holds enough ice to raise world sea levels by at least 3.3 meters (11 feet) if it ever all melted, a process that would take centuries. 

"The western part of the ice sheet is experiencing nearly twice as much warming as previously thought," Ohio State University said in a statement of the study led by its geography professor David Bromwich. 

The warming "raises further concerns about the future contribution of Antarctica to sea level rise," it said. Higher summer temperatures raised risks of a surface melt of ice and snow even though most of Antarctica is in a year-round deep freeze. 

Low-lying nations from Bangladesh to Tuvalu are especially vulnerable to sea level rise, as are coastal cities from London to Buenos Aires. Sea levels have risen by about 20 centimeters (8 inches) in the past century. 

The United Nations panel of climate experts projects that sea levels will rise by between 18 and 59 cms (7-24 inches) this century, and by more if a thaw of Greenland and Antarctica accelerates, due to global warming caused by human activities.

The rise in temperatures in the remote region was comparable to that on the Antarctic Peninsula to the north, which snakes up towards South America, according to the U.S.-based experts writing in the journal Nature Geoscience. 

Parts of the northern hemisphere have also warmed at similarly fast rates. 

Annual bird counts give scientists climate clues

Several ice shelves - thick ice floating on the ocean and linked to land - have collapsed around the Antarctic Peninsula in recent years. Once ice shelves break up, glaciers pent up behind them can slide faster into the sea, raising water levels.

"The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous West Antarctic ice sheet glaciers," said Andrew Monaghan, a co-author at the U.S. National Center for Atmospheric Research. 

The Pine Island glacier off West Antarctica, for instance, brings as much water to the ocean as the Rhine river in Europe. 

The scientists said there had been one instance of a widespread surface melt of West Antarctica, in 2005. "A continued rise in summer temperatures could lead to more frequent and extensive episodes of surface melting," they wrote. 

Watch World News videos on NBCNews.com

West Antarctica now contributes about 0.3 mm a year to sea level rise, less than Greenland's 0.7 mm, Ohio State University said. The bigger East Antarctic ice sheet is less vulnerable to a thaw. 

Helped by computer simulations, the scientists reconstructed a record of temperatures stretching back to 1958 at Byrd, where about a third of the measurements were missing, sometimes because of power failures in the long Antarctic winters. 

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Osama Faisal / AP

Activists criticizing what they called a slow pace to climate talks protest Saturday at the convention center in Qatar. Norway's environment minister, Bard Vegar, speaks to some of them.

DOHA, Qatar -- Almost 200 nations on Saturday extended until 2020 a weak international plan for fighting global warming, averting a new setback to two decades of U.N. efforts that have failed to halt rising greenhouse gas emissions. 

The eight-year extension of the Kyoto Protocol keeps it alive as the sole legally binding plan for combating global warming. But it was sapped by the withdrawal of Russia, Japan and Canada, so its signatories now account for only 15 percent of global greenhouse emissions.

A package of decisions, known as the Doha Climate Gateway, would also postpone until 2013 a dispute over demands from developing nations for more cash to help them cope with global warming.

All sides say the Doha decisions fell far short of recommendations by scientists for tougher action.

Though expectations were low for the two-week conference, many developing countries rejected the deal as insufficient to put the world on track to fight the rising temperatures that are raising sea levels. Some Pacific island nations see this as a threat to their existence.

"This is not where we wanted to be at the end of the meeting, I assure you," said Nauru Foreign Minister Kieren Keke, who leads an alliance of small island states. "It certainly isn't where we need to be in order to prevent islands from going under and other unimaginable impacts."

"It was not an easy ride. It was not a beautiful ride. It was not a fast ride, but we managed to cross the bridge and hopefully we can increase our speed," added European Climate Commissioner Connie Hedegaard.

She said the deal would pave the way to talks on a new, global U.N. pact meant be agreed in 2015 and enter into force in 2020, when Kyoto now expires. It will have emissions goals for all, including emerging nations led by China and India.

The 1997 Kyoto Protocol, which controls the greenhouse gas emissions of rich countries, expires this year. However, the second phase only covers about 15 percent of global emissions after Canada, Japan, New Zealand and Russia opted out.

Originally, Kyoto obliged about 35 industrialized nations to cut greenhouse gas emissions by an average of at least 5.2 percent below 1990 levels during the period from 2008 to 2012.

The U.S. never joined Kyoto, partly because it didn't include China and other fast-growing developing countries.

Poor countries came into the talks in Doha demanding a timetable on how rich countries would scale up climate change aid for them to $100 billion annually by 2020 — a general pledge that was made three years ago.

But rich nations -- including the United States, members of the European Union and Japan -- are still grappling with the effects of a financial crisis and were not interested in detailed talks on aid in Doha.

The agreement on financing made no reference to any mid-term financing targets, just a general pledge to "identify pathways for mobilizing the scaling up of climate finance."

The two-week U.N. meeting had been due to end on Friday but the talks went on into Saturday evening.

World carbon dioxide emissions are set to rise by 2.6 percent this year, and are more than 50 percent higher than in 1990. Recent growth has come mostly from emerging nations, led by China and India.

The Associated Press and Reuters contributed to this report.

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What had been a blurry picture about polar ice — especially how it impacts sea levels — just got a whole lot clearer as experts on Thursday published a peer-reviewed study they say puts to rest the debate over whether the poles added to, or subtracted from, sea level rise over the last two decades.

"This improved certainty allows us to say definitively that both Antarctica and Greenland have been losing ice," lead author Andrew Shepherd of the University of Leeds in Britain, told reporters. Not only that, but the pace has tripled from the 1990s, the data indicate.

Combining satellite data from dozens of earlier studies, the study "shows that the Antarctic and Greenland ice sheets have contributed just over 11 millimeters (0.4 inches) to global sea levels since 1992," he added. Two-thirds was from Greenland, a third from Antarctica.

NASA Earth Observatory

This 20-mile-long rift on Antarctica's Pine Island Glacier, seen from a satellite on Oct. 26, will eventually calve off, possibly in the next few months, creating an iceberg the size of New York City. While that won't raise sea levels since the glacial tongue sits on water, the loss could speed up the flow of ice from Antarctica's mainland into the sea.

That's 20 percent of all sea level rise over the last two decades, with the rest mostly from thermal expansion of waters due to warming sea temperatures, the authors noted. In recent years, however, the percentage "has gone up significantly" to nearly 40 percent, added co-author Michiel van den Broeke from Utrecht University in the Netherlands.

Published in the journal Science, the study was based on input from 47 experts at the 26 institutes that produced earlier studies with wild variations. Some of those studies estimated melt was raising sea levels by up to 2 millimeters a year, Shepherd noted, while a few said that overall polar ice was growing, and thus countering sea level rise.

Much of the discrepancy was due to data showing that Antarctica's vast eastern ice sheet was adding, not losing ice.

Eastern Antarctica has indeed added ice, but continent-wide the last decade shows a "50 percent increase in ice loss rate," said study co-author Erik Ivins, a satellite data expert with NASA's Jet Propulsion Lab. 

Most of that loss is in western Antarctica — at places like Pine Island Glacier, where an iceberg the size of New York City is set to calve off. The iceberg itself won't raise sea levels since that ice is already atop water, but thinning glaciers mean that ice on the mainland can make its way downhill to the sea faster.

ESA/NASA/Planetary Visions

Based on the new study in Science, this chart shows changes in global sea level due to ice sheet melting since 1992. The background image shows thickening (blue) and thinning (red) of Antarctica's ice sheets over the same period.

Even more dramatic, Ivins said, is that Greenland "is losing mass at about five times the rate today as it was in the early 1990s."

Greenland's melt rate has gone from 55 billion tons a year in the 1990s to nearly 290 billion tons a year recently, according to the study. 

A top ice expert who was not a study co-author told NBC News that the new data mark "an important step forward" in better estimating future sea level rise.

"While we had a basic picture of what was going on, it was an incomplete and blurry one," said Mark Serreze, director of the National Snow and Ice Data Center at the University of Colorado-Boulder. "We needed to step back and take a fresh look, making the best use of all of the different data sources that we have.

"With this study," he added, "we now have a lot confidence in how the ice sheets are behaving."

The findings come as nations negotiate in Qatar over a new climate treaty to replace the 1997 Kyoto Protocol, which aimed to reduce carbon dioxide and other greenhouse gases tied to a warming Earth. 

And while a 0.4 inch rise in sea levels over 20 years doesn't sound like much, many experts fear further warming will accelerate the polar melt. The ice sheets would raise sea levels by more than 200 feet if they completely melted over centuries — not likely, but even a tenth of that would have catastrophic impacts on coastal areas.

The authors warned that while the new data should become the benchmark for future forecasts, any new studies could be compromised if aging satellites are not replaced. In the U.S., the Obama administration is overhauling its satellite program after an outside review team found it "dysfunctional."

Related: Sea levels rose 60 percent faster than forecast, study finds

"It’s really critical that these measurements are sustained and several satellites are beginning to fail," noted Ian Joughin, a University of Washington researcher.

"If we really want to have meaningful information that you know planners can use to build seawalls," he added, "there’s going to have to be a big push to improve our projections of sea level rise using models."

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Projections for sea level rise in coming decades could be too conservative, experts warned Wednesday, saying they found that the rise over the last two decades is much more than predicted by the U.N. scientific body tracking climate signals.

In a peer-reviewed study, the experts said satellite data show sea levels rose by 3.2 millimeters (0.1 inch) a year from 1993 to 2011 — 60 percent faster than the 2 mm annual rise projected by the U.N.'s Intergovernmental Panel on Climate Change for that period. 

"This suggests that IPCC sea-level projections for the future may also be biased low," the team wrote in the journal Environmental Research Letters. 

The experts also said the IPCC was just about spot on with its predictions for warming temperatures.

"Global warming has not slowed down or is lagging behind the projections," lead author Stefan Rahmstorf, a researcher at Germany's Potsdam Institute for Climate Impact Research, said in a statement. "The IPCC is far from being alarmist and in fact in some cases rather underestimates possible risks." 

The experts added that the faster sea level rise is unlikely to be caused by a temporary ice discharge from Greenland or Antarctica ice sheets because it correlates very well with the increase in global temperature.

The IPCC earlier estimated that seas rose by about 7 inches over the last century, and its most recent report, published in 2007, estimated a range of between 7 and 23 inches this century — enough to worsen coastal flooding and erosion during storm surges.

But the IPCC report did not factor in a possible acceleration of the melt of the Greenland and Antarctic ice sheets.

The IPCC "assumed that Antarctica will gain enough (ice) mass" to compensate for Greenland ice loss, the new study's authors noted, but more recent studies have shown that "the ice sheets in Greenland and Antarctica are increasingly losing mass."

Related: Ice melt found across 97 percent of Greenland

Rahmstorf told Reuters his best estimate for sea level rise was between 20 inches and three feet this century, possibly more if greenhouse gas emissions of carbon dioxide surged.

The IPCC chair, addressing delegates to international climate talks being held in Doha, Qatar, on Wednesday made note of the recent findings on ice loss and sea level rise.

The next IPCC report, Rajendra Pachauri promised, will have "a better appreciation of mass loss of the large ice sheets of Greenland and Antarctica."

When the next IPCC report comes out in March 2014, he added, expect "a more quantitative understanding of ongoing sea level rise" — and an entire chapter on the topic.

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DOHA, Qatar -- Despite cooling from La Nina early in the year, 2012 is on track to become one of the top 10 warmest years on record, with the U.S. experiencing extreme warmth and Arctic Sea ice shrinking to its lowest extent, the U.N. weather agency said Wednesday.

In a statement released at international climate talks in Qatar, the World Meteorological Organization said the "alarming rate" of the Arctic melt highlights the far-reaching changes caused by global warming.

"Climate change is taking place before our eyes and will continue to do so as a result of the concentrations of greenhouse gases in the atmosphere, which have risen constantly and again reached new records," WMO Secretary-General Michel Jarraud said.

Delegates from nearly 200 countries are meeting in Doha, Qatar, to discuss ways of slowing climate change, including by cutting emissions of greenhouse gases that scientists say are warming the planet, melting ice caps, raising sea levels, and changing rainfall patterns with impacts on floods and droughts.

Discord between rich and poor countries on who should do what has kept the two-decade-old U.N. talks from delivering on that goal, and global emissions are still going up.

The WMO said global temperatures rose after initial cooling caused by the La Nina weather oscillation, with major heat waves in the U.S. and Europe. Average temperatures in January-October were the highest in the continental U.S., and the ninth highest worldwide, since records began in 1850.

Cyclone activity was normal globally, but above average in the Atlantic, where 10 storms reached hurricane strength, including Sandy, which wreaked havoc across the Caribbean and the U.S. East Coast.

Sandy wasn't the strongest cyclone, though. That was Typhoon Sanba, which struck the Philippines, Japan, and the Korean Peninsula, "dumping torrential rain and triggering floods and landslides that affected thousands of people and caused millions in U.S. dollars in damage," the WMO said.

Related: Permafrost melt needs to be factored into talks, experts say

Droughts impacted the U.S., Russia, parts of China and northern Brazil. Nigeria saw exceptional floods, while southern China saw its heaviest rainfall in three decades.

But of all the weather events in 2012, the most ominous to climate scientists was the loss of ice cover on the North Pole. In September, scientists at the National Snow and Ice Data Center in Colorado said Arctic Sea ice measured 1.32 million square miles — which is 18 percent less than the previous record low, set in 2007. Records go back to 1979 based on satellite tracking.

The scientists said their computer models predict the Arctic could become essentially free of ice in the summer by 2050, but added that current trends show ice melting faster than the computers are predicting.

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All the back and forth over climate change negotiations hasn't dealt with a looming problem: melting permafrost could account for more than a third of all warming emissions by 2100, experts warned Tuesday, and yet nations haven't factored it into reduction targets.

"Permafrost is one of the keys to the planet’s future because it contains large stores of frozen organic matter that, if thawed and released into the atmosphere, would amplify current global warming," U.N. Environment Program Director Achim Steiner said in announcing the report by top permafrost scientists.

"Continuing to ignore the challenges of warming permafrost" is not an option, he added.

The report was released as nations gather in Doha, Qatar, this week for the latest round of climate treaty talks that aim to limit warming by the year 2100 to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial temperatures.

"Permafrost has begun to thaw," lead author Kevin Schaefer, a researcher at the National Snow and Ice Data Center at the University of Colorado-Boulder, told a news conference in Doha.

"Permafrost emissions could ultimately account for up to 39 percent of total (greenhouse gas) emissions," he warned. "This must be factored into treaty negotiations ... or we risk overshooting the 2 degrees Celsius maximum warming target."

Permafrost, defined as ground that stays frozen for at least two years in a row, stores vast quantities of carbon dioxide and methane, both gases that contribute to the greenhouse effect warming the Earth.

United Nations Environment Program

This map shows one scenario of permafrost melt using climate models. The scenario shows a nearly 59 percent loss in near-surface permafrost by 2100.

Widespread thaw would create a vicious circle, since the release of more CO2 and methane would trap more heat in the air and in turn accelerate the melting. That, in turn, could bring an irreversible, runaway effect. 

The experts predicted an irreversible loss of between 30 and 85 percent of permafrost near the surface. That was based on a forecast of Arctic temperatures rising by 6 degrees C (10.8 F) through 2100.

The permafrost report follows reports by the World Bank and the U.N. Environment Program warning that rising world greenhouse gas emissions, even without permafrost contributions, were on track to push up temperatures well beyond 2 degrees C by 2100. 

At Doha, nations are negotiating around extending the Kyoto Protocol — a legally-binding emissions cap that expires this year. 

Many rich countries such as Japan, Russia and Canada have refused to endorse an extension and want a completely new treaty. The United States was the lone industrialized country not to join the original pact in 1997 because it did not include other big emitters like China. 

Japan insists it would be better to focus on a new treaty by 2015.

"Only developed countries are legally bound by the Kyoto Protocol and their emissions are only 26 percent," Masahiko Horie, speaking for the Japanese delegation, said in Doha. "If we continue the same, only one quarter of the world is legally bound and three quarters of countries are not bound at all."

Related story: Rich-poor split persists at climate talks

But developing countries like Brazil are warning that it will be difficult for poor nations to do their part if they continue watching industrialized nations shy away from legally-binding pacts like Kyoto. 

Reuters and The Associated Press contributed to this report.

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