Ice Melting in the Arctic

This page has links to science articles discussing the melting of ice in the Arctic and to effects from that melting.

The remaining Arctic sea ice cover is much thinner on average than it was years ago. Satellite imagery, submarine sonar measurements, and data collected from NASA's Operation IceBridge, an airborne survey of polar ice, indicate that the Arctic sea ice thickness is as much as 50 percent thinner than it was in previous decades, going from an average thickness of 12.5 feet (3.8 meters) in 1980 to 6.2 feet (1.9 meters) in recent years. The thinning is due to the loss of older, thicker ice, which is being replaced by thinner seasonal ice.

"Rapid Arctic sea ice loss is probably the most visible indicator of global climate change; it leads to shifts in ecosystems and economic access, and potentially impacts weather throughout the northern hemisphere," said Overland. "Increased physical understanding of rapid Arctic climate shifts and improved models are needed that give a more detailed picture and timing of what to expect so we can better prepare and adapt to such changes. Early loss of Arctic sea ice gives immediacy to the issue of climate change."

In a paper published March 31 in Nature Climate Change, scientists reveal new models projecting that wooded areas in the Arctic could increase by as much as 50 percent over the coming decades. The researchers also show that this dramatic greening will accelerate climate warming at a rate greater than previously expected.

The new maximum -- 5.82 million square miles (15.09 million square kilometers) -- is in line with a continuing trend in declining winter Arctic sea ice extent: nine of the ten smallest recorded maximums have occurred during the last decade. The 2013 winter extent is 144,402 square miles (374,000 square kilometers) below the average annual maximum extent for the last three decades.

Ongoing glacier loss in the Canadian high Arctic is accelerating and probably irreversible, new model projections by Lenaerts et al. suggest. The Canadian high Arctic is home to the largest clustering of glacier ice outside of Greenland and Antarctica -- 146,000 square kilometers (about 60,000 square miles) of glacier ice spread across 36,000 islands.

The widespread reduction in Arctic sea ice is causing significant changes to the balance of greenhouse gases in the atmosphere. This is shown in a new study conducted by researchers from Lund University in Sweden, among others.

Ancient carbon trapped in Arctic permafrost is extremely sensitive to sunlight and, if exposed to the surface when long-frozen soils melt and collapse, can release climate-warming carbon dioxide gas into the atmosphere much faster than previously thought.

It came out of Siberia, swirling winds over an area that covered almost the entire Arctic basin in the normally calm late summer. It came to be known as "The Great Arctic Cyclone of August 2012," and for some observers it suggested that the historic sea ice minimum may have been caused by a freak summer storm, rather than warming temperatures.

Melting Arctic sea ice is no longer just evidence of a rapidly warming planet -- it's also part of the problem.

The Arctic sea ice has not only declined over the past decade but has also become distinctly thinner and younger. Researchers are now observing mainly thin, first-year ice floes which are extensively covered with melt ponds in the summer months where once metre-thick, multi-year ice used to float. Sea ice physicists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), have now measured the light transmission through the Arctic sea ice for the first time on a large scale, enabling them to quantify consequences of this change.

As much as 44 billion tons of nitrogen and 850 billion tons of carbon stored in arctic permafrost, or frozen ground, could be released into the environment as the region begins to thaw over the next century as a result of a warmer planet, according to a new study led by the U.S. Geological Survey. This nitrogen and carbon are likely to impact ecosystems, the atmosphere, and water resources including rivers and lakes. For context, this is roughly the amount of carbon stored in the atmosphere today.

Earth's poles have very different geographies. The Arctic Ocean is surrounded by North America, Greenland and Eurasia. These large landmasses trap most of the sea ice, which builds up and retreats with each yearly freeze-and-melt cycle. But a large fraction of the older, thicker Arctic sea ice has disappeared over the last three decades. The shrinking summer ice cover has exposed dark ocean water that absorbs sunlight and warms up, leading to more ice loss.
On the opposite side of the planet, Antarctica is a continent circled by open waters that let sea ice expand during the winter but also offer less shelter during the melt season. Most of the Southern Ocean's frozen cover grows and retreats every year, leading to little perennial sea ice in Antarctica.

The near-record ice melt occurred without the unusual weather conditions that contributed to the extreme melt of 2007. In 2007, winds and weather patterns helped melt large expanses of ice. "Atmospheric and oceanic conditions were not as conducive to ice loss this year, but the melt still reached a new record low," said NSIDC scientist Walt Meier. "This probably reflects loss of multi-year ice in the Arctic, as well as other factors that are making the ice more vulnerable." Multi-year ice is ice that has survived more than one melt season and is thicker than first-year ice.

With the melting ice in the Arctic, U.S. Coast Guard crews based in Alaska have taken on a new challenge: carefully deploying scientific equipment through cracks in the ice from an airplane hundreds of feet in the air.

Yackel and the university-based Cryosphere Climate Research Group use satellite technology to research the physical properties of Arctic ice. As recently as the 1980s, most of the ice in the Arctic Ocean was "multi-year ice," -- thick ice that would remain throughout the summer. At that time, the split between multi-year ice and seasonal ice -- ice that would melt away in the summer -- was about 80 per cent multi-year and 20 per cent seasonal.
"In the last 20 years we've almost gotten to the point where we've reversed that ratio," Yackel says, predicting the ice extent that covers the Arctic Ocean "is likely to be gone in the summers within the next 20 to 25 years, if not sooner."

The frozen cap of the Arctic Ocean appears to have reached its annual summertime minimum extent and broken a new record low on Sept. 16, the National Snow and Ice Data Center (NSIDC) has reported. Analysis of satellite data by NASA and the NASA-supported NSIDC at the University of Colorado in Boulder showed that the sea ice extent shrunk to 1.32 million square miles (3.41 million square kilometers).

"The snowfall rate increases slightly in the middle of winter by the end of the century," Hezel said. However, at the same time sea ice is expected to start forming later in the year than it does now. The slightly heavier snowfall in the winter won't compensate for the fact that in the fall -- which is also when it snows the heaviest -- snow will drop into the ocean instead of piling up on the ice.

According to the new research, glaciers on Canada's Baffin Island expanded rapidly during a brief cold snap about 8,200 years ago. The discovery adds to a growing body of evidence showing that ice sheets reacted rapidly in the past to cooling or warming, raising concerns that they could do so again as Earth heats up.

Global warming in the Arctic is mysteriously occurring more quickly 1.2 miles (2 kilometers) above the surface than at ground level, a new study says.

To discover how the situation has changed since the last ice age, researchers studied 20,000-year-old mud samples from the sub-Arctic Pacific Ocean lying approximately three feet below the present sea bed. They found the water in the ocean’s depths exchanged less CO2 with the atmosphere than it does at present, while capturing more atmospheric CO2 than the water does today, suggesting as oceans become warmer as a result of climate change they release more carbon dioxide into the atmosphere. [posted by NewsDaily on January 24, 2008]

Arctic ice has reformed rapidly this winter after a record summer low, but it still covers less of the Arctic Ocean than it did in previous decades, NASA scientists announced today in an update of the states of Arctic and Antarctic sea ice.

Today’s Arctic explorers are well-acquainted with the ugly haze that hangs over the North Pole, created by air pollution that drifts up from cities in lower latitudes. But a new study suggests this veil of pollution has been present since the late 1800s.

The thickest, oldest and toughest sea ice around the North Pole is melting, a bad sign for the future of the Arctic ice cap, NASA satellite data showed on Tuesday. [posted by NewsDaily on March 18, 2008]

NOAA scientists are now flying through springtime Arctic pollution to find out why the region is warming — and summertime sea ice is melting — faster than predicted. Some 35 NOAA researchers are gathering with government and university colleagues in Fairbanks, Alaska, to conduct the study through April 23.

A team of scientists including polar expert Dr. Derek Mueller from Trent University and Canadian Rangers have discovered that the largest ice shelf in the Northern Hemisphere has fractured into three main pieces.

The ice cover in the Arctic Ocean at the end of summer 2008 will lie, with almost 100 per cent probability, below that of the year 2005 — the year with the second lowest sea ice extent ever measured. Chances of an equally low value as in the extreme conditions of the year 2007 lie around eight per cent. Climate scientists from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association come to this conclusion in a recent model calculation.

Most glaciers in every mountain range and island group in Alaska are experiencing significant retreat, thinning or stagnation, especially glaciers at lower elevations, according to a new book published by the U.S. Geological Survey. In places, these changes began as early as the middle of the 18th century.

Until recent years, measurements have shown most Arctic ice has survived at least one summer and often several, said Meier. But the balance has now flipped, and seasonal ice -- which melts and re-freezes every year -- now comprises about 70 percent of Arctic sea ice in winter, up from 40 to 50 percent in the 1980s and 1990s, he said. Thicker ice that has survived two or more years now comprises just 10 percent of ice cover, down from 30 to 40 percent in years past.

The Arctic ice cap grows each winter as the sun sets for several months and intense cold ensues. In the summer, wind and ocean currents cause some of the ice naturally to flow out of the Arctic, while much of it melts in place. But not all of the Arctic ice melts each summer; the thicker, older ice is more likely to survive. Seasonal sea ice usually reaches about 2 meters (6 feet) in thickness, while multi-year ice averages 3 meters (9 feet).

New evidence for ice-free summers with intermittent winter sea ice in the Arctic Ocean during the Late Cretaceous – a period of greenhouse conditions – gives a glimpse of how the Arctic is likely to respond to future global warming.

The findings, detailed in the Sept. 4 issue of the journal Science, also suggest that if it weren’t for these manmade pollutants, temperatures around the North Pole would actually be cooling as a result of natural climate patterns.

Based on its long-term orbit, Earth should be heading into an ice age. But instead of continuing to cool—as it had been for at least the past 2,000 years—the Arctic has started to warm. And the reason is humans’ impact on the composition of the atmosphere, new research suggests.

Sea ice is like rainforest in the tropics. There are species that can’t live without it,” says ecologist Eric Post of The Pennsylvania State University, lead author of a paper in the September 11 Science that lays out a broad review of climate change’s impact on the Arctic. “It’s melting earlier, freezing up later, the contiguous extent is diminishing, and it’s happening faster than anyone expected it to happen 10 years ago.”

The possibility that climate change might simply be a natural variation like others that have occurred throughout geologic time is dimming, according to evidence in a Proceedings of the National Academy of Sciences paper published October 19.

The research team, led by Étienne Berthier of the Laboratory for Space Studies in Geophysics and Oceanography at the Université de Toulouse in France, says that glacier melt in Alaska between 1962 and 2006 contributed about one-third less to sea-level rise than previously estimated.

“The sea ice acts like a shiny lid on the Arctic Ocean. When it is heated, it reflects most of the incoming sunlight back into space. When the sea ice melts, more heat is absorbed by the water. The warmer water then heats the atmosphere above it.”

Scientists from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association (AWI) in Bremerhaven and from KlimaCampus of the University of Hamburg have now published data in this context in the annual issue of Sea Ice Outlook. The online publication compares the forecasts on ice cover for September 2010 prepared by around a dozen international research institutes in a scientific “competition.” The ice reaches its minimum area at this time every year.

While this year’s September minimum extent was greater than 2007 and 2008, the two record-setting and near-record-setting low years, it is still significantly below the long-term average and well outside the range of natural climate variability, according to CU-Boulder’s NSIDC scientists. Most researchers believe the shrinking Arctic sea ice is tied to warming temperatures caused by an increase in human-produced greenhouse gases being pumped into Earth’s atmosphere.

“Other sea ice data are available from other data providers, using different satellite sensors and sea ice algorithms. For example, data from the University of Bremen indicate that sea ice extent from their algorithm fell below the 2007 minimum. They employ an algorithm that uses high resolution information from the JAXA AMSR-E sensor on the NASA Aqua satellite. This resolution allows small ice and open water features to be detected that are not observed by other products. This year the ice cover is more dispersed than 2007 with many of these small open water areas within the ice pack. While the University of Bremen and other data may show slightly different numbers, all of the data agree that Arctic sea ice is continuing its long-term decline.”

A new study led by the Georgia Institute of Technology provides further evidence of a relationship between melting ice in the Arctic regions and widespread cold outbreaks in the Northern Hemisphere. The study’s findings could be used to improve seasonal forecasting of snow and temperature anomalies across northern continents.

Scientists from the Woods Hole Oceanographic Institution (WHOI) have conducted a new study to measure levels of carbon at various depths in the Arctic Ocean. The study, recently published in the journal Biogeosciences, provides data that will help researchers better understand the Arctic Ocean's carbon cycle -- the pathway through which carbon enters and is used by the marine ecosystem. It will also offer an important point of reference for determining how those levels of carbon change over time, and how the ecosystem responds to rising global temperatures.

"At this point we can only speculate as to how the mercury enters the river systems, but it appears that climate change may play a large role," says Jacob. "As global temperatures rise, we begin to see areas of permafrost thawing and releasing mercury that was locked in the soil; we also see the hydrological cycle changing, increasing the amount of runoff from precipitation that enters the rivers."

That's because melting Arctic sea ice can trigger a domino effect leading to increased odds of severe winter weather outbreaks in the Northern Hemisphere's middle latitudes -- think the "Snowmageddon" storm that hamstrung Washington, D.C., during February 2010.

However, in situ observations made in September 2009 by Barber et al. show that much of the ice was in fact “rotten” ice — ice that is thinner, heavily decayed, and structurally weak due to a uniform temperature throughout.

They show that the extreme warm periods in the Arctic correspond closely with times when parts of Antarctica were also ice-free and warm, suggesting a strong connection between Northern and Southern Hemisphere climate.

The combination of melting sea ice and global atmospheric warming are contributing to the high rate of warming in the Arctic, where temperatures are increasing up to four times faster than the global average, a new University of Melbourne study has shown.

Researchers are working hard to improve their ability to more accurately predict how much Arctic sea ice will remain at the end of summer. It's an important exercise because knowing why sea ice declines could help scientists better understand climate change and how sea ice is evolving.

"What we see in Nares Strait is some of the hardest and thickest ice leaving the Arctic where some of it is replaced by much thinner ice that has not been hardened by many sequential freeze/melt cycles," Muenchow says. "The harder thicker ice is called 'multi-year' ice, distinct from first-year ice, and the slow disappearance of this multi-year ice from northern Canada and Greenland is one major factor causing the ice extent to become steadily smaller over the last 40 years or so. Most climate models predicted this scenario, but we are 30 to 40 years ahead of the predicted schedule with regard to the ice cover in the Arctic."

The extent of the sea ice covering the Arctic Ocean has shrunk. According to scientists from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colo., the amount is the smallest size ever observed in the three decades since consistent satellite observations of the polar cap began.