Tag Archives: ice sheet

The Greenland Ice Sheet is leaking mercury — likely natural, but still dangerous

As climate change keeps making our planet hotter and our glaciers melty, scientists report on an unforeseen issue: glacial meltwater from the Greenland Ice Sheet contains high levels of mercury, a toxic heavy metal. According to the report, these levels are comparable to those in rivers where factories dump their waste, creating a major threat to the seafood industry and people who enjoy its products.

Image via Pixabay.

It’s never a dull day with environmental woes. A study that began as an effort to analyze the quality of meltwater from the Greenland ice sheet, and how nutrients therein might support coastal wildlife, ended up uncovering very high levels of mercury in the runoff. The finding raises new questions about how global warming will impact wildlife in the region, one of the foremost exporters of seafood worldwide.

Mermaids, mercury

“There are surprisingly high levels of mercury in the glacier meltwaters we sampled in southwest Greenland,” said Jon Hawkings, a postdoctoral researcher at Florida State University and the German Research Centre for Geosciences. “And that’s leading us to look now at a whole host of other questions such as how that mercury could potentially get into the food chain.”

Together with glaciologist Jemma Wadham, a professor at the University of Bristol’s Cabot Institute for the Environment, Hawkings initially set out to sample water from three different rivers and two fjords next to the Greenland Ice Sheet. Their aim was to understand how nutrients from glacial meltwater can help to support coastal ecosystems.

Although they also measured for mercury, they didn’t expect to find any meaningful concentrations. Which made the levels of this metal they found in the water all the more surprising.

The baseline for mercury content in rivers is considered to be about 1 to 10 ng / L-1. That’s roughly equivalent to a sand grain of mercury in an Olympic pool of water — so, very low. However, the duo found that mercury levels in the water they sampled were in excess of 150 ng / L-1. Mercury levels in the sediment (called “glacial flour” when it’s produced by glaciers) were over 2000 ng / L-1, which is simply immense.

So far, it remains unclear whether mercury levels drop farther away from this ice sheet, as meltwater gets progressively more diluted. It’s also not yet clear whether the metal is making its way into the marine food web, which would likely make it concentrate further (as animals eat plants and each other).

Although the findings are local, the issue could have global ramifications, as they echo findings in other arctic environments. Greenland is an important producer of seafood, with the export of cold-water shrimp, halibut, and cod being its primary industry. If mercury here does end up in the local food web, it could unknowingly be exported to and consumed by people all over the world.

“We didn’t expect there would be anywhere near that amount of mercury in the glacial water there,” said Associate Professor of Earth, Ocean, and Atmospheric Science Rob Spencer, co-author of the paper. “Naturally, we have hypotheses as to what is leading to these high mercury concentrations, but these findings have raised a whole host of questions that we don’t have the answers to yet.”

“For decades, scientists perceived glaciers as frozen blocks of water that had limited relevance to the Earth’s geochemical and biological processes. But we’ve shown over the past several years that line of thinking isn’t true. This study continues to highlight that these ice sheets are rich with elements of relevance to life.”

Roughly 10% of our planet’s dry land is covered in ice, and the results here raise the worrying possibility that they may be seeping mercury into the waters around them. The issue is compounded by the fact that global warming is making these glaciers melt faster, while we still have an imperfect understanding of how the melting process influences the local geochemistry around them.

So far, the team explains that this mercury is most likely coming from a natural source, not from something like fossil fuel use or industrial activity. While this is very relevant for policy-makers, the fact remains that natural mercury is just as toxic as man-made mercury. If it is sourced from natural processes, however, managing its levels in the wild will be much more difficult to do .

“All the efforts to manage mercury thus far have come from the idea that the increasing concentrations we have been seeing across the Earth system come primarily from direct anthropogenic activity, like industry,” Hawkings said. “But mercury coming from climatically sensitive environments like glaciers could be a source that is much more difficult to manage.”

The paper “Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet” has been published in the journal Nature Geoscience.

Global ice loss rate increased by over 65% in the last two decades

New research reports that the planet is losing ice at an ever-faster rate. This is the first time satellite data has been used to survey global ice loss rates, according to the authors, finding that it has increased by over 50% in the last three decades, and 65% over the last two decades.

Furthermore, the authors explain that our planet has lost around 28 trillion tons of ice between 1994 and 2017, which they say is roughly the same quantity in an ice sheet the size of the UK and 100 meters thick — and the rate of melt is increasing. If left unchecked, this will lead to massive damage as communities and natural habitats on today’s coasts will flood.

No-more-ice Age

“Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most. The ice sheets are now following the worst-case climate warming scenarios set out by the Intergovernmental Panel on Climate Change,” says lead author Dr. Thomas Slater, a Research Fellow at Leeds’ Centre for Polar Observation and Modelling.

“Sea-level rise on this scale will have very serious impacts on coastal communities this century.”

Led by members from the University of Leeds, the team reports that there has been a 65 % increase in the rate of melt over the 23 years it investigated, driven mainly by losses in Antarctica and Greenland. In raw numbers, we went from 0.8 trillion tons of ice melting per year in the 1990s to 1.3 trillion tons per year by 2017.

Although we had a better idea than ever before about how individual elements in the Earth’s ice system fared, we were still lacking data on how the planet as a whole was evolving. This study, says Dr. Slater, is the first to examine all of the ice at the same time, using satellite data. It includes 215,000 mountain glaciers, the ice sheets of Greenland and Antarctica, ice shelves around Antarctica, as well as sea ice bobbing along the Arctic and Southern Oceans.

The faster rates of melt are being caused by warmer waters and bodies of air — the atmosphere and oceans have warmed by 0.26°C and 0.12°C per decade since the 1980, respectively. Atmospheric melting was the prime offender (responsible for around 68% of the extra melting), with the remainder (32%) coming down to oceanic melting. The geographic distribution of ice on the planet explains the higher rates of atmospheric melting (not all ice comes in contact with the ocean).

All the elements investigated in the study lost ice, but the largest losses were in Arctic Sea ice (7.6 trillion tons) and Antarctic ice shelves (6.5 trillion tons). Mountain glaciers lost a total of 6.1 trillion tons of ice, the Greenland ice sheet lost 3.8 trillion tons, while the Antarctic ice sheet lost some 2.5 trillion tons of ice.

This contributed around 35 millimeters of global sea level rise. The team explains that every centimeter of sea level rise puts an estimated one million people at risk of being displaced by water.

“Sea ice loss doesn’t contribute directly to sea level rise but it does have an indirect influence. One of the key roles of Arctic sea ice is to reflect solar radiation back into space which helps keep the Arctic cool,” says Dr. Isobel Lawrence, a Research Fellow at Leeds’ Centre for Polar Observation and Modelling.

“As the sea ice shrinks, more solar energy is being absorbed by the oceans and atmosphere, causing the Arctic to warm faster than anywhere else on the planet. Not only is this speeding up sea ice melt, it’s also exacerbating the melting of glaciers and ice sheets which causes sea levels to rise.”

Mountain glaciers contributed around 25% of the sea level rise seen over this period, despite storing only 1% of the world’s ice. Their melting is especially worrying, as mountain glaciers are essential sources of fresh water for communities around the world.

It is estimated that for every centimetre of sea level rise, approximately a million people are in danger of being displaced from low-lying homelands.

The paper “Review article: Earth’s ice imbalance” has been published in the journal The Cryosphere.

Ancient Mars watercourses may have been carved by ice sheets, not flowing rivers

Early Mars may have looked like this landscape of the Devon ice cap. Credit: Anna Grau Galofre.

The Red Planet is littered with branching, desiccated systems of trenches and valleys that seem to have been carved by flowing water, and are likely 3.5 to 4 billion years old. A new study, however, makes the bold assertion that most of these valley networks were actually carved by water melting beneath glacial ice rather than free-flowing rivers.

Glacial Mars

In 1877, Italian astronomer Giovanni Schiaparelli first observed mysterious straight lines along the planet’s equatorial regions, which he called canali (canals). However, what he saw was merely an optical illusion produced by the lens of his telescope. But, as it turns out, there really are canali, or watercourses, on Mars. It was only much later, with the advent of high-resolution telescopes and after we sent spacecraft to Mars, that this became obvious.

The image below captured by ESA’s Mars Express satellite in 2019 is illustrative in this regard. It shows a system of valleys located in the southern highlands of Mars, east of a huge impact crater called Huygens and north of Hellas, which is the largest impact basin on the red planet. The dendritic pattern akin to tree branches or brain cells is what you’d expect to see for a world that is covered in rivers (like Earth) or that used to host such free-flowing water systems (like is believed to have been the case in early Mars).

Credit: ESA.

But for Anna Grau Galofre, a former PhD student at the University of British Columbia, these channels don’t look at all like they were made by ancient Martian rivers.

She and colleagues examined thousands of Martian valleys and compared them to subglacial channels in the Canadian Arctic Archipelago, finding striking similarities.

“For the last 40 years, since Mars’s valleys were first discovered, the assumption was that rivers once flowed on Mars, eroding and originating all of these valleys,” says Grau Galofre. “But there are hundreds of valleys on Mars, and they look very different from each other. If you look at Earth from a satellite you see a lot of valleys: some of them made by rivers, some made by glaciers, some made by other processes, and each type has a distinctive shape. Mars is similar, in that valleys look very different from each other, suggesting that many processes were at play to carve them.”

The team’s work was initially inspired by subglacial channels on Devon Island in the Canadian Arctic. Devon, with its inhospitable polar climate and glaciation, is one of the best analogous of Mars here on Earth. If the two are so similar, could have many of the red planet’s geological features also been shaped by glacial processes?

Using a novel machine-learning algorithm, the researchers were able to go through 10,000 Martian valleys, looking for patterns that underlie different erosion processes. Turns out that most of the channels seem to have been carved by subglacial erosion and only a fraction of valley networks match patterns typical of surface water erosion.

“These results are the first evidence for extensive subglacial erosion driven by channelized meltwater drainage beneath an ancient ice sheet on Mars,” says co-author Mark Jellinek, who is a professor in UBC’s department of earth, ocean, and atmospheric sciences. “

These new findings topple the conventional view of Mars’ valley systems on its head. Although it might require more substantial evidence to be embraced by the scientific community, the findings also make sense in the context of early Mars.

Scientists believe that Mars’ valley systems were formed around 3.8 billion years ago — a time when the sun was less intense and Mars received less sunshine.

“Climate modelling predicts that Mars’ ancient climate was much cooler during the time of valley network formation,” says Grau Galofre, currently a SESE Exploration Post-doctoral Fellow at Arizona State University. “We tried to put everything together and bring up a hypothesis that hadn’t really been considered: that channels and valleys networks can form under ice sheets, as part of the drainage system that forms naturally under an ice sheet when there’s water accumulated at the base.”

Life may have still found a way

The new study casts doubt over the conventional view of a wet Mars, dotted with flowing river systems, encased in a thick atmosphere that may have been conducive to life.

However, this alternative scenario doesn’t lower the odds of ancient Mars supporting life. In fact, if anything, the odds were more favorable since ice sheets would have offered more protection for any life forms in the underlying water.

And even if Mars’ famous canali weren’t carved by glaciers, the analytical tools developed by the researchers are still mighty useful. The same approach can be applied to geological features here on Earth, in order to uncover hidden patterns about our planet’s early history.

“Currently we can reconstruct rigorously the history of global glaciation on Earth going back about a million to five million years,” says Jellinek. “Anna’s work will enable us to explore the advance and retreat of ice sheets back to at least 35 million years ago–to the beginnings of Antarctica, or earlier–back in time well before the age of our oldest ice cores. These are very elegant analytical tools.”

Paradise Bay, Antarctica. Credit: Max Pexel.

Antarctica is losing six times more ice than 40 years ago

Paradise Bay, Antarctica. Credit: Max Pexel.

Paradise Bay, Antarctica. Credit: Max Pexel.

The longest-ever assessment of Antarctic ice mass paints a bleak picture for the future. Between 1979 and 2017, Antarctica has experienced a sixfold increase in yearly ice mass loss — and this rate doesn’t seem to be slowing down. During this period, global sea levels rose by almost 13 millimeters (half an inch) and might continue to rise at a higher rate than previously estimated.

“That’s just the tip of the iceberg, so to speak,” lead author Eric Rignot, who is an Earth scientist at the University of California Irvine, said in a statement. “As the Antarctic ice sheet continues to melt away, we expect multi-meter sea level rise from Antarctica in the coming centuries.”

Antarctica contains 90% of the world’s glacier ice – enough ice to raise world sea level by over 60 meters (almost 200 feet) if it were all to melt. However, Antarctica’s ice sheet — composed of the East Antarctic Ice Sheet and the West Antarctic Ice Sheet — is not a giant mass of stationary ice but rather a system with inputs and outputs of matter and energy.  All glaciers, from the smallest cirque glaciers to the largest ice sheets, are conveyors of ice – transporting ice from areas of net input (the accumulation zone) to areas of net output (the ablation zone).

The continent’s glaciers accumulate ice from snowfall, and these snow crystals are buried under more recent precipitation, eventually reaching a depth where they are compacted into glacier ice. But, because of the massive pressure, the glacier flows like a very viscous liquid towards the ocean (at a rate so slow it’s impossible to perceive the movement), slowly leaving the continent in the form of icebergs and other pieces of floating ice that eventually melt altogether. It’s when the outflow rate is greater than the snowfall accumulation rate that sea levels rise — and this is happening more than ever.

Credit: British Antarctic Survey.

Credit: British Antarctic Survey.

Rignot and colleagues studied 18 regions, totaling 176 basins, as well as surrounding islands. In order to assess the ice sheet balance, the research team used high-resolution aerial photos taken by NASA’s Operation IceBridge from an altitude of 350 meters, in conjunction with satellite radar interferometry from various space agencies and ongoing Landsat satellite imagery which first began in the early 1970s.

Slippery slope

Credit: imbie/Planetary Visions.

Credit: imbie/Planetary Visions.

The results suggest that between 1979 and 1990, Antarctica outflowed an average of 40 gigatons of ice mass annually, where a gigaton is equal to one billion tons. This ice loss rate jumped to a staggering 252 gigatons of ice loss per year between 2009 and 2017 — that’s six times more ice loss than four decades ago.

The biggest ice loser was the West Antarctic Ice Sheet, which is capable of driving almost 5 meters (17 feet) of sea level rise. It is now losing about 159 gigatons of ice yearly, particularly due to the melting of the Pine Island glacier (which lost a trillion tons of ice since 1979) and the Thwaites Glacier (which lost 634 billion tons).

However, the most surprising result was the rate of net ice loss in East Antarctica, which is by far the continent’s biggest ice vault, capable of nearly 52 meters (170 feet) of sea level rise. Significant ice loss is experienced by the Cook, Ninnis, Dibble, Frost, Holmes, and Denman glaciers. Denman alone has lost 200 billion tons of ice, according to the study. Previously, climate scientists thought that East Antarctica wasn’t so vulnerable to net ice loss, but that may all be wishful thinking.

“This region is probably more sensitive to climate [change] than has traditionally been assumed, and that’s important to know, because it holds even more ice than West Antarctica and the Antarctic Peninsula together,” said Rignot, who’s also a senior project scientist at NASA JPL.

Antarctica’s ice sheet is melting due to global warming, which disproportionately affects the poles. The bulk of this melt is not due to to surface melting but rather melting that comes from below. In the Antarctic, the ice shelves extend from the land out over the water. And, since the bottom of the ice shelf is exposed to the ocean, which is warming up, it can melt the underside of the shelf and cause it to thin or break off into the ocean.

“As climate warming and ozone depletion send more ocean heat toward those sectors, they will continue to contribute to sea level rise from Antarctica in decades to come,” Rignot added.

The findings appeared in the Proceedings of the National Academy of Sciences.

Meltwater slides off Greenland's massive ice sheet into the ocean during hot summer days. Credit: Woods Hole Oceanographic Institution.

Greenland melting is ‘off the charts’ — It’s unprecedented in the last 400 years, scientists warn

Meltwater slides off Greenland's massive ice sheet into the ocean during hot summer days. Credit: Woods Hole Oceanographic Institution.

Meltwater slides off Greenland’s massive ice sheet into the ocean during hot summer days. Credit: Woods Hole Oceanographic Institution.

Greenland’s ice sheet is melting faster than at any point in the last four centuries, researchers warn in a new study. The findings are especially worrisome since Greenland’s ice sheet — which is 1.5-kilometer thick and covers 1,710,000 square kilometers — could raise sea levels by up to seven meters if it completely vanished. “From a historical perspective, today’s melt rates are off the charts, and this study provides the evidence to prove this,” said Sarah Das, a glaciologist at Woods Hole Oceanographic Institution (WHOI) and co-author of the study.

A history trapped in ice

Scientists had known that Greenland’s massive ice sheet is melting at an accelerated rate, based on satellite observations. But the question on everybody’s mind has always been how fast. And because reliable satellite monitoring of the area only dates back to the early 1990s, it’s also challenging to gauge exceptional warming events from background warming rates. For instance, 2012 was particularly intense, with 97% of the entire ice sheet experiencing surface melting for a few days.

In a new study, an international team of researchers found that while 2012 was indeed unusually warm for Greenland, the ice sheet’s dramatic warming may simply be a preview of what’s in store for the future. Their unprecedented analysis, which offers a melting record going back centuries, shows that the ice sheet has been melting at a faster rate than previous estimated, even faster than air temperatures are increasing.

“Melting of the Greenland Ice Sheet has gone into overdrive. As a result, Greenland melt is adding to sea level more than any time during the last three and a half centuries, if not thousands of years,” said Luke Trusel, a glaciologist at Rowan University’s School of Earth & Environment and former post-doctoral scholar at Woods Hole Oceanographic Institution, and lead author of the study. “And increasing melt began around the same time as we started altering the atmosphere in the mid-1800s,” said the researcher, alluding to a human activity as the likely culprit for this warming.

In order to come up with a historical record of Greenland’s ice melt, the research team drilled ice cores from the ice sheet at sites more than 1,800 meters above sea level. Researchers drilled at such high elevations for good reason. Greenland experiences seasonal melt during the warm summer days, and at low elevations, the melting is more intense. At such locations, meltwater runs off the ice sheet and into the ocean, contributing to sea level rise — but in the process, no record of the melt remains. Contrary, at higher elevations, the meltwater quickly refreezes due to contact with the snowpack underneath. Instead of escaping the ice sheet, the short-lived meltwater forms icy bands that stack up layers of densely packed ice over time. In the case of the cores drilled by the researchers, the record goes back into the 17th century.

Traffic-pole-sized ice cores were sent to labs in the United States where their physical and chemical properties were assessed. Dark bands running horizontally across the cores record the strength of the melting for a given year. Thicker bands signify years of higher melting, while thinner bands indicate years of less intense melting.

The results from the ice cores were combined with observations from satellites and climate models. The researchers claim that the thickness of the annual melt layers can also track how much melting was occurring at different sites, at the lower-elevations edges of the ice sheet. In other words, their new findings cover melting broadly, across the much of the ice sheet.

Writing in the journal Nature, the authors conclude that runoff in Greenland started to steadily rise when the first signs of climate change hit the Arctic, in the mid-19th century. However, it accelerated dramatically in the past 20 years, at a rate six-fold higher than before the Industrial Revolution.

“We have had a sense that there’s been a great deal of melting in recent decades, but we previously had no basis for comparison with melt rates going further back in time,”  Matt Osman, co-author of the new study, said in a statement. “By sampling ice, we were able to extend the satellite data by a factor of 10 and get a clearer picture of just how extremely unusual melting has been in recent decades compared to the past.”

The authors also note that Greenland’s ice sheet is much more vulnerable to melting than before. Data suggests that even small changes in temperature caused exponential increases in melting in recent years — a non-linear response that points to feedback effects. Since surface temperatures in the Arctic are rising faster than any other place on Earth, these findings don’t bode well for the future of Greenland’s ice sheet — and with it, our own.

Credit: British Antarctic Survey.

What Greenland’s landscape looks like without any ice

The most detailed map of Greenland’s topography was released this week by a team of British and American researchers. An accompanying video simulates what the massive island would look like if it were free of ice. Speaking of which, the new findings suggest that Greenland’s ice sheet has the potential to contribute more to global sea level rise than believed.

Credit: British Antarctic Survey.

Credit: British Antarctic Survey.

Greenland’s ice sheet is immense. Covering more than 660,000 square miles, thicker than a mile, and measuring a volume of 684,000 cubic miles, it would drown anything lower than 25 feet (~7.5 meters) above sea level were it to melt.

The new map carted by researchers at the British Antarctic Survey (BAS), the University of Bristol, and the University of California at Irvine (UCI), now offers a glimpse of what the island’s topography looks like under that huge blanket of ice.

We can see streams on top of valleys carved by water that used to flow well before the ice sheet even existed. The valley system creates perfect lubricating conditions for meltwater to run off and discharge into the ocean. What’s more, Greenland’s topography could foster the creation of more channels in the future, further speeding up the run-off.

Already, Greenland lost 269 billion tons of ice each year since 2002. According to an earlier study, meltwater sourced from Greenland’s ice sheet accounted for 25 percent of the global sea level rise in 2014.

This refined view also shows that Greenland’s ice sheet is thicker than previously thought, in some places by up to 100 meters.

“This new compilation of the 3-D landscape beneath the Greenland Ice Sheet provides the first seamless transition between the landmass and its adjoining seabed, and this gives scientists a bird’s eye view of the fringes of Greenland which are experiencing the most changes,” said BAS cartographer Peter Fretwell, who was involved in producing the printed map.

“What’s also surprising is that there is more ice and the bed is deeper in some places than previous maps suggest, so this means the total contribution from the ice sheet to global sea level rise would be 7.42 meters if it were to melt completely, slightly higher than previously calculated,” he added.

To make this detailed map, scientists employed data collected by different instruments operated by over 30 institutions worldwide. This includes data collected by satellites, airborne and ground-based radar, as well as seabed mapping from ships. A printed 1:3,500,000 scale version was presented this week at the American Geophysical Union meeting in New Orleans. A summy of the paper has been published in the journal Geophysical Research Letters.

“This map will improve our understanding of the ice-ocean interactions and how the ice sheet will evolve in a changing climate,” said glaciologist professor Jonathan Bamber at the University of Bristol who had a NERC-funded project to develop the printed map and data set.

Another study published on Wednesday in Science Advances found that in 2003, the ice sheet over Greenland suddenly began melting at a much faster rate. For instance, ice sheet run-off into the Tasersiaq catchment, which spans more than 2,500 square miles, increased by 80 percent compared to the average runoff rate in the decades prior. This suggests that global warming, though increasing gradually, can set off sharp, massive shifts in ice melt.

A new rift in West Antarctica's Pine Island Glacier, photographed during a NASA Operation IceBridge flyover on 4 November 2016. Image: NASA/Nathan Kurtz.

Unless coal is phased out by 2050, Antarctica’s melting ice sheet could drive a massive surge in sea level rise

If CO2 emissions from burning coal continue on their unabated track, Antarctica’s ice sheets could cross a dangerous tipping point where sea levels rise dramatically. According to climate scientists at Climate Analytics, coal needs to virtually disappear from the global energy mix by 2050 if we’re to avert a scenario where millions of people living on Pacific Islands and low-lying shores are forced to displace.

A new rift in West Antarctica's Pine Island Glacier, photographed during a NASA Operation IceBridge flyover on 4 November 2016. Image: NASA/Nathan Kurtz.

A new rift in West Antarctica’s Pine Island Glacier, photographed during a NASA Operation IceBridge flyover on 4 November 2016. Image: NASA/Nathan Kurtz.

Staying within a strict carbon budget, which entails massively reducing fossil fuel use in favor of more renewable energy, would still lead to half a meter (1.6 feet) of sea level rise by the end of the century. Many experts say this is an overly optimistic scenario that, even so, threatens low-lying populations. That’s still not nearly as catastrophic as ‘business as usual’, though. A new Climate Analytics study published in the journal Environmental Research Letters found more than 1.9 degrees Celsius of warming could cause a run-off effect in West Antarctic Ice Sheet. The melting would accelerate the pace of sea level rise with dire consequences of people’s livelihoods.

The study employed the latest findings in science (high-resolution seafloor imaging, novel modeling techniques) to assess the risks possessed by severe melting of Antartica’s Ice Sheet. The work suggests that previous estimates for sea level rise by the year 2100 in the range of 0.9 meters (3 feet) are too conservative. Rather, an extreme scenario will likely see sea level rise by an estimated 1.32 meters (4.3 feet) if the world continues on its course burning ungodly quantities of fossil fuels through the century. That is 50% more than previously estimated by the IPCC’s AR5 report.

Previous work suggests Antarctic ice sheets and glaciers become more sensitive to higher levels of warming. As more meltwater infiltrates the cracks inside the ice sheet and glaciers, ice will pry apart. Meanwhile, warm ocean water will free floating shelves from rocky anchors, casting them out into the sea.

A call for more ambitious action

The findings underscore how vital it is for nations to stay on track with the Paris Agreement whose goal is to limit global warming to no more than 1.5 degrees Celsius over Industrial Age readings. However, the pledges which governments have made so far are not ambitious enough. To avoid potentially disastrous Antarctic melting, nations will have to slash carbon emissions much deeper, with coal — the ‘dirtiest’ energy source — being the low-hanging fruit in this case.

According to the researchers, if we’re to limit sea level rise to about half a meter, coal shouldn’t make up more than 5% of the world’s energy mix by 2050. Under this scenario, carbon is taxed at US$100 per tonne to provide businesses and governments the necessary incentive to ditch coal and other fossil fuels.

Some developed countries are already well aware how coal emissions threatened the environment and the health of their citizens. This week, news broke that Italy’s government is planning to phase out coal completely by 2025. Elsewhere, similar measures have been announced in Finland (2030), the UK (2025), Indonesia (2030) or the Netherlands (2030). To date, six countries, states, provinces or cities have completely phased out coal power since 2014, and an additional 17 have announced a coal power phase-out date of 2030 or sooner, according to a recent Greenpeace report.

greenland-1962999_960_720

Global sea levels rose 50% faster than two decades ago because of Greenland’s melting ice sheet

The rate of global sea level rise has increased by about 50 percent in just the last two decades, according to an international team of researchers. In 1993, global sea levels increased from a rate of 2.2 millimeters/year to 3.3 millimeters/year in 2014. The dramatic increase is believed to be mostly caused by melting of Greenland’s ice sheet.

greenland-1962999_960_720

The Greenland Ice Sheet contributed 5 percent of the total sea level rise in 1993, by 2014 this figure increased to about 25 percent. Credit: Pixabay.

These findings suggest that the world’s sea levels are rising faster than thought only a couple of years ago. If this accelerated trend continues, devastating consequences might ensue. The Intergovernmental Panel on Climate Change (IPCC), which is the UN science advisory body, estimates that by the end of the century sea levels could rise by 60 to 90 centimeters (24 to 35 inches). This very conservative projection, however, assumes the rate at which sea level rises stays constant.

Sea level rise due to global warming is a serious threat, on a collision course with large and growing coastal populations. Hundreds of millions of people live in low-lying deltas around the world and only a few feet extra in sea level is enough to force them out.

Global warming drives sea level rise by two major mechanisms:

  • by warming ocean water; as it warms, water expands, taking up more space

  • by melting land-based ice (glaciers and ice sheets), sending more water to our oceans.

According to a new study published in Nature Climate Change, accelerating losses of mass from Greenland and Antarctica are driving up the rate of sea level rise. The researchers fixed some loose ends in satellite altimetry data, which gauges heights on the Earth’s surface from space, using satellites. Until recently, the data showed little change in sea levels over the last two decades even when other measurements like in-situ clearly showed an increase in the levels.

“We corrected for a small but significant bias in the first decade of the satellite record,” co-author Xuebin Zhang, a professor at Qingdao National Laboratory of Marine Science and Technology in China’s Shandong Province, told AFP.

While thermal expansion accounted for almost half of added sea level rise in the early 1990s, two decades later that figure was only 30 percent. Instead, contributions from ice sheets and glaciers have increased from about half of the total rise in 1993 to around 70 per cent in 2014. Most of this sharp increase can be pinned on the melting of the Greenland ice sheet which now supplies 25 percent of total sea level increase compared with just five percent 20 years earlier. Greenland contains enough frozen water to lift oceans by about seven meters (23 feet).

Even if we cease dumping greenhouse gases into the atmosphere tomorrow, sea level rise that will continue because global warming is already locked-in and by some account triggered feedback loops are accelerating warming. For instance, despite the amount of CO2 released into the atmosphere has stabilized in the last five years, CO2 levels in the atmosphere are rising — and fast. As such, these findings must serve as a wake-up call for policymakers. The cost of non-action could be dramatic by the end of the century.

West Antarctic ice sheet is melting from the inside, signaling an accelerated collapse

A rift in Pine Island Glacier ice shelf, West Antarctica, photographed from the air during a NASA Operation IceBridge survey flight, Nov. 4, 2016. This is the second rift to form on the ice shelf in the last couple of years. The first led into the break off a huge iceberg in 2015. Credit: NASA/Nathan Kurtz.

Last year, a huge 225-square-mile iceberg broke off the ever thinning Pine Island Glacier, in Antarctica. The iceberg served as a wake-up call for everyone, signaling the depreciating state of the glacier.

“It’s generally accepted that it’s no longer a question of whether the West Antarctic Ice Sheet will melt, it’s a question of when,” said Ian Howat, associate professor of earth sciences at Ohio State.

http://i.giphy.com/pkV2NtFxEko4E.gif

When Howat and colleagues analyzed satellite imagery in the intervening years before the iceberg broke off, they came across something unusual — shadows that were cast many miles inland, away from the warming waters of the Antarctic coast. The rift which formed some 20 miles away from the base of the ice shelf steadily grew in size over two years until it weakened the ice beneath enough to cause it to collapse.

“This kind of rifting behavior provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes,” Howat said.

https://youtu.be/n25ubwdpccU

This is the first time researchers have direct evidence of a deep subsurface rift opening within Antarctic ice. However, we know from earlier research that similar breakups occurring in the Greenland Ice Sheet are caused by corridors through which warm water seeps through the bedrock, melting the ice from beneath. Because the bottom of the West Antarctic Ice sheet is actually beneath sea level ocean water can intrude inland and escape detection.

“Rifts usually form at the margins of an ice shelf, where the ice is thin and subject to shearing that rips it apart,” Howat explained. “However, this latest event in the Pine Island Glacier was due to a rift that originated from the center of the ice shelf and propagated out to the margins. This implies that something weakened the center of the ice shelf, with the most likely explanation being a crevasse melted out at the bedrock level by a warming ocean.”

The research suggests new valleys forming inland in Antarctica’s ice sheets could be hints of ice melting far below and, consequently, impending collapse. Howat notes that there are many such features observed by previous surveys suggesting the state of melting in Antarctica could be far more accelerated than previously believed.

Pine Island Glacier and its twin, the Thwaites Glacier, sit right beneath one of the most active ice flows on the continent. These act like cork bottles, keeping roughly 10 percent of the West Antarctic Ice Sheet from disintegrating and melting. The whole West Antarctic Ice Sheet itself is already considered unstable with some studies forecasting it will break down by 2100. If it melts, the ice sheet could raise global sea levels by 10 feet, putting large cities like New York or Miami under water. Overall, 150 million could be displaced.

Antarctic ice sheet decline evident since the 1940s — and it’s irreversible

A researcher inspecting a sediment core drilling from 1,000 feet beneath the Pine Island Glacier ice shelf. Credit: M. Brian/Nature

A researcher inspecting a sediment core drilled from 1,000 feet beneath the Pine Island Glacier ice shelf. Credit: M. Brian/Nature

Another study published in Nature documented how researchers drilled holes in the Pine Island Glacier ice shelf during December 2012 and January 2013. The cores they extracted revealed the lithology and composition of sediments trapped beneath the ice while lead and plutonium isotopes tell us when the ice retreat began, and what the temperature was like.

“What you find with the sediment cores is essentially a history of what has been going on at the bottom over the last couple of decades, because the sedimentation on the ocean floor is quite different once you have an ocean cavity from when you have ice actually touching the ground,” said University of Alaska, Fairbanks physics professor Martin Truffer for PBS.

The analysis of the sediment cores extracted from Pine Island showed the grounding line of the glacier has retreated roughly 30 miles in the last 70 years due to a sudden pulse of warm water in 1945. Despite the temperature recovered soon after, returning to a cool state, the cavity formed behind the grounding line ridge only got bigger.

Ice retreat and thinning since a warm pulse kicked off an irreversible melting in 1945. Credit: Smith et al., 2016/Nature.

Ice retreat and thinning since a warm pulse kicked off an irreversible melting in 1945. Credit: Smith et al., 2016/Nature.

These results suggest sudden climate forcing can cause irreversible melting.

“There’s an enormous amount of ice there,” said Truffler. “So, the question becomes, ‘Can you release that in 100 years or 1,000 years?’ I think the rate of retreat is where most of the uncertainty is right now.”

Meltwater on the Greenland ice sheet carved this canyon. Credit: IAN JOUGHIN

New subglacial lakes discovered in Greenland accelerating melting

Using satellite imagery, scientists have discovered two new subglacial lakes under Greenland’s ice sheet bringing the total number to four. The discovery is not well met, however. These lakes are already drained, signaling that climate change is making its way beneath the Greenland ice sheet. The discovery suggests subglacial lakes could increase the sensitivity of ice to climatic change, further accelerating ice melt.

Lakes beneath the thick Greenland ice

Meltwater on the Greenland ice sheet carved this canyon.  Credit: IAN JOUGHIN

Meltwater on the Greenland ice sheet carved this canyon. Credit: IAN JOUGHIN

Scientists were intrigued by an unusual summer melting season in 2011. Then,  billions of gallons of water had flushed some 30 miles (50 kilometers) to the sea, leaving behind sunken craters in the surface of the ice above the lakes.  Michael Bevis, of the School of Earth Sciences at Ohio State University in Columbus, and colleagues used satellite imagery to inspect the anomaly and found a lake corresponded for each of the two huge craters, nested beneath the huge Greenland ice sheet.

[ALSO SEE] Frozen underworld discovered under Greenland ice sheet

Greenland’s ice sheet is the second largest ice sheet in the world after Antarctica and it covers almost 80 percent of the island. The island has 2.8 million cubic kilometers volume of ice and at some spots the ice is about 3 kilometers thick.

The first lake had been there for around 40 years, and was filled with 6.7 billions of gallons of water or enough to fill 10,000 Olympic swimming pools.  However, based on more recent satellite images, the lake seems to have dried up, around 4 years ago, in 2011.  The crater left, stretches on a distance of 1.2 miles all around and across, and has a depth of 70 metres, the height of a ten story building.

The second lake  in northeastern Greenland has filled and drained twice since its first blowout in 2011. Since it’s  230 feet (70 meters) deep, this tells us quite a bit about the state of warming and water melting in the region. The water itself is meltwater from the ice sheet’s surface, trickling downward through cracks in the ice. But this repeated depletion and refilling of the lake can only mean that there’s of excess heat affecting the ice sheet.

“This is a new mechanism for getting heat from the top of the ice cap to the bottom of the ice cap, and I think it’s likely that we’ll see it happening at other places in the future,” said Michael Willis, lead author of the Nature study and a glaciologist at Cornell University and the University of North Carolina at Chapel Hill.

“If enough water is pouring down into the Greenland Ice Sheet for us to see the same subglacial lake empty and refill itself over and over, then there must be so much latent heat being released under the ice that we’d have to expect it to change the large-scale behavior of the ice sheet,” said Michael Bevis, a geophysicist at Ohio State University and co-author of the Nature study.

A lake under the ice in northeast Greenland that emptied and is now refilling with surface water that drains downward through cracks. (Image: Cornell University)

A lake under the ice in northeast Greenland that emptied and is now refilling with surface water that drains downward through cracks. (Image: Cornell University)

The two lakes are quite important because they tell us how the ice sheet’s  Basal ice layer performs. The basal layer is the part of the glacier in which the nature of the ice is directly affected by proximity to the glacier bed.  The meltwater, the results of rising global temperatures, essentially lubricates the basal layer and makes it more likely to slide out to sea, researchers said.

Global warming has already affected Greenland considerably. Between 2003 and 2012, the northeast region of Greenland’s ice sheet receded nearly 20 kilometers. Yet because of the  amount of water draining into the subglacial lakes the ice sheet will only get softer due to the heat. This can only mean more ice lost – far more than previously estimated.

In Antarctica, there are 400 such lakes entombed beneath its thick ice, but in Greenland scientists have only discovered four, including the two reported now. Researchers believe there may be more lakes, but never as many as those in Antarctica. The steep topology of Greenland simply doesn’t allow it, as water is quickly led out to sea.

“I think there will be more lakes, but I think that we won’t find that these lakes are a major player in the behavior of the large-scale behavior of the ice sheet,” said Garry Clarke, a glaciologist at the University of British Columbia who was not involved in the two studies.

Over the 19 years studied, the Greenland ice sheet lost 2.7 trillion metric tons of ice — about the same mass as 8 million Empire State Buildings. The Antarctic ice sheet also shrank, by about 1.3 trillion metric tons. That is roughly the equivalent of 4 million Empire State Buildings.

The findings were reported in the journal Nature.

Projected Arctic shipping routes.

Global warming will open shipping routes directly through the North Pole by 2050

A group of researchers assessed seven individual climate models and found that in each case common open water vessels will be able to navigate through portions of the Arctic, currently possible only with icebreaker ships, by the mid-century. Moreover, the thinning ice will allow ice-strengthened vessels to sail directly over the pole, something currently unimaginable, dramatically shortening travel distance, time and cost. The new shipping routes also means that governments need to revise their policies in order to tackle environmental, political and strategic threats.

Last year, a total of 46 ships made their way through the north of Russia via the “northern sea route” – considerably more than in the past due to a seven year streak of ever thinning Arctic ice. After assessing climate forecasts for the years 2040 to 2059, University of California researchers found that open water vessels should be able to travel along this route without the need of being escorted by icebreaker ships by 2050.

“We’re talking about a future in which open-water vessels will, at least during some years, be able to navigate unescorted through the Arctic, which at the moment is inconceivable,” says PhD candidate Scott Stephenson.

Projected Arctic shipping routes.

Projected Arctic shipping routes.

Moreover, the Arctic ice sheet is expect to thin and retreat to such an extent that polar icebreakers will be able to head from the Pacific to the Atlantic ocean by traveling straight across the North Pole. The best period for such an endeavor will be September, when historically annual sea ice cover in the Arctic Ocean is at its lowest extent.

Previously we’ve reported on a separate study that reached similar findings in its projections for the future, however this is the first to assert the sound possibility of an open shipping route through the North Pole itself.

“Nobody’s ever talked about shipping over the top of the North Pole,” says geography professor Laurence Smith. “This is an entirely unexpected possibility.”

With this in mind, in 2050 a shorter northern sea route is expected to save medium-sized bulk carrier 18 days and 580 tonnes of bunker fuel on a journey between northern Norway and China, translating in economic savings between $200,000 and $350,000 per trip. A journey straight through the North pole would mean 40% in savings, however.

New shipping routes mandate, however, new regulations which the world’s governments need now to consider. Russia, Canada and the United States will most likely engage in arguments over sea water sovereignty in the near future. Bitter picking between governments for economic benefits is of least interest to us however, what’s important is that strict laws regarding environmental protection that need to be put in place. The future’s Arctic routes are currently home to pristine environments that might become unbalanced as a result of busy and polluting ships.

“The prospect of common open water ships, which comprise the vast majority of the global fleet, entering the Arctic Ocean in late summer, and even its remote central basin by moderately ice-strengthened vessels heightens the urgency for a mandatory International Maritime Organisation regulatory framework to ensure adequate environmental protections, vessel safety standards, and search-and-rescue capability,” the report says.

The UCLA findings were reported in the journal PNAS.

Antactic ice sheet retreat

Antarctic rift the size of the Grand Canyon speeds ice sheet melting

Antactic ice sheet retreat

Scientists from Britain have found a remote ice rift valley, up to one mile deep, under the ice in Antarctica. The rift is similar in size and depth to the Grand Canyon and because it is direct contact with the warming ocean, it’s been found that it has a significant contribution to the unusual ice sheet melting of West Antarctica.

The rift lies beneath the Ferrigno Ice Stream on a stretch of coast so remote that it has only been visited once previously in 1961.

“Over the last 20 years we have used satellites to monitor ice losses from Antarctica, and we have witnessed consistent and substantial ice losses from around much of its coastline.”

For some of the glaciers, including Ferrigno Ice Stream, the losses are especially pronounced, and, to understand why, we needed to acquire data about conditions beneath the ice surface,” said Glaciologist and lead author, Dr Robert Bingham.

The ice sheet in West Antarctic is losing ice at a faster rate than any other part of the continent and some glaciers are receding annually by over one metre. Actually, it’s been found that West Antarctica’s thinning ice adds almost 10% to global rises in sea levels. You can imagine this didn’t went unnoticed, so scientists decided to closely investigate the area.

Using a special tower radar mounted on-top of a snowmobile, researchers were able to survey the area through which they traversed, roughly 1,500 miles.

“What we found is that lying beneath the ice there is a large valley, parts of which are approximately a mile deeper than the surrounding landscape,” said Dr Bingham.

“If you stripped away all of the ice here today, you’d see a feature every bit as dramatic as the huge rift valleys you see in Africa and in size as significant as the [US] Grand Canyon.

“This is at odds with the flat ice surface that we were driving across – without these measurements we would never have known it was there.”

After analyzing the valley geometry and correlating the warm ocean with which it is linked, the scientists found that it matches satellite ice thinning data. In the paper, the scientists claim that the Ferrigno Rift is part of a massive rift system that is little understood.

The study is part of the British Antarctic Survey’s Icesheets Programme that investigates how ice sheets change and what effect they have on the rest of the earth, including rises in sea levels. It’s thought that were the entire ice sheets of Antarctica and Greenland to melt, which are 4km thick, sea levels globally would rise by several metres.

The findings were reported in the journal Nature.

Satellite photo of the Petermann glacier before the giant iceberg broke off the ice sheet. Notice a significant crack shaped like a circle arc. (c) NASA

Iceberg twice the size of Manhattan breaks off Greenland glacier

Researchers at the University of Delaware and the Canadian Ice Service recently reported that an ice island, whose surface is twice that of Manhattan, broke off from Greenland’s Petermann Glacier, one of the two largest glaciers left in Greenland connecting the great Greenland ice sheet with the ocean via a floating ice shelf.

The 46-square-mile giant iceberg broke off from the glacier on Monday, and has since started its journey towards the open ocean.The on-site discovery was confirmed with satellite imaging from the Moderate Resolution Imaging Spectroradiometer aboard NASA’s Terra and Aqua satellites.

Satellite photo of the Petermann glacier before the giant iceberg broke off the ice sheet. Notice a significant crack shaped like a circle arc. (c) NASA

Satellite photo of the Petermann glacier before the giant iceberg broke off the ice sheet. Notice a significant crack shaped like a circle arc. (c) NASA

An hour and a half after the previous image was taken, this photo shows the iceberg has begun to move toward the open ocean. (c) NASA

An hour and a half after the previous image was taken, this photo shows the iceberg has begun to move toward the open ocean. (c) NASA

Although the new iceberg is admitedly large, it rather pales in comparison to its predecessor from 2010, when a chuck of ice 97-square-mile chunk of ice broke off from the Petermann Glacier – the largest iceberg recorded in the Arctic since 1962. Last year, on the other side of the world, an iceberg the size of New York City broke off from the Antarctic ice sheet – 340-square-miles in surface.

Greenland ice sheet is melting and shrinking

“While the size is not as spectacular as it was in 2010, the fact that it follows so closely to the 2010 event brings the glacier’s terminus to a location where it has not been for at least 150 years,” says Andreas Muenchow, associate professor of physical ocean science and engineering in UD’s College of Earth, Ocean, and Environment.

“The Greenland ice sheet as a whole is shrinking, melting and reducing in size as the result of globally changing air and ocean temperatures and associated changes in circulation patterns in both the ocean and atmosphere,” he notes.

Muenchow points out that the air around northern Greenland and Ellesmere Island has warmed by about 0.11 +/- 0.025 degrees Celsius per year since 1987. This means Northern Greenland and Canada have been warming five times faster than the average global temperature, according to the scientist.

“Northwest Greenland and northeast Canada are warming more than five times faster than the rest of the world,” Muenchow says, “but the observed warming is not proof that the diminishing ice shelf is caused by this, because air temperatures have little effect on this glacier; ocean temperatures do, and our ocean temperature time series are only five to eight years long — too short to establish a robust warming signal.”

This is not an isolated incident. Many of glaciers in southern Greenland have been melting at an unusual rapid pace. If it continues, and more of the Petermann is lost, the melting would push up sea levels – the ice lost so far was already floating, so the breaks don’t add to global sea levels.

The new iceberg is expected to follow in the footsteps of the previous 2010 giant glacier, breaking apart into smaller icebergs as it moves away north, then west, before reaching the shores of Newfoundland.

Source: University of Delaware via Our Amazing Planet

Antarctica ice-sheet

Ice sheets in Antarctica formed by massive fall in CO2

Antarctica ice-sheetAntarctica is the most the arid place on Earth. Its climate is so rough, so hazardous that no permanent human populace can live there, however just a few million years ago the harsh plains of the south and north poles had a subtropical climate – a paradise for life. During a transition period of just 100,000 years, a blink of an eye in geological timeline, the temperature went down dramatically and thus the same ice sheets that are in place today were formed. Scientists have been debating for some time what lead to this event, and now a new research shows that a massive fall in the amount of atmospheric carbon dioxide is the true culprit.

The research shows CO2 level plunged by 40 percent before and during the formation of the ice sheet 34 million years ago, during the Eocene to Oligocene climate transition, when the first ice shards formed. Previously it was assumed that a change in ocean currents was the cause for the sudden drop in temperature, however this couldn’t be farther from the truth – quite the opposite. It is quite evident when the Southern Ocean currents and temperatures of that period – vastly different from today – are factored in, it becomes apparent that Antarctica’s big freeze followed a fall in CO2 levels.

“Our research recognised that the flows of deep ocean currents at the end of the Eocene were dramatically different from those of today because of the altered position and shape of continental masses,” says NSW Climate Change Research Centre researcher Dr Willem Sijp.

“Previous research relied on different temperature estimates and had also not taken these different currents into account. This decline was a critical condition for global cooling and the emergence of the Antarctic ice sheet. In short, the apparent increase of CO2 during Antarctic glaciation is refuted.”

The estimates in carbon dioxide levels millions of years ago were possible by analyzing  ancient algae remnants from deep-ocean sediments, in which they observed a change in their biochemical molecules that correspond with the sudden CO2 drop. The measurements where factored in with the ocean currents from that period.

The whole event signified a major tipping point in Earth’s climate. Imagine just that a few millions of years before the cooling, the southern and northern poles of the planet were warm and wet, inhabited by a luxuriant tropical vegetation and fauna. Today, the ice sheets of Antarctica are over one kilometers thick and exercise a fundamental influence across the whole globe, from impacting the circulation of cold and warm air masses to wind strength, precipitation patterns and variability in regional and global temperatures.

“The onset of Antarctic ice is the mother of all climate ‘tipping points,'” says Pagani. “Recognizing the primary role carbon dioxide change played in altering global climate is a fundamentally important observation.”

The research found that the tipping point in atmospheric carbon dioxide levels for cooling that initiates ice sheet formation is about 600 parts per million. At present day, we’re currently nearing 400 million parts per million, which is more than enough to keep the ice sheets in place for a lot of time to come, the researchers claim.

“The system is not linear and there may be a different threshold for melting the ice sheet, but if we continue on our current path of warming we will eventually reach that tipping point,” says Huber. “Of course after we cross that threshold it will still take many thousands of years to melt an ice sheet.”

This highly remarkable event from Earth’s recent history shows just how important greenhouse gases are on the climate.

The new findings were reported in the journal Science

 

Antarctica’s amazing striped icebergs

When you think of Antarctica, pristine white icebergs usually come to mind; probably the last thing you’d expect are humbug-like striped icebergs, with blue, green, yellow and even brown.

The different colours appear due to various reasons, but generally speaking they appear because some layers of ice form in special conditions. Blue stripes are the most common, and they appear when crevices are filled with water and they freeze so fast that no bubbles are formed. However, things are different with the other ones.

Green appears because the water that freezes is extremely rich in algae, hence the colour. Brown, yellow, and even black stripes are caused by sediments picked up along the way when the ice sheet was sliding downhill.

They’re not exactly rare, but quite uncommon still. It was Norwegian sailor Oyvind Tangen, on board a research ship that first photographed and described these glaciers (from what I was able to find, I’m not quite sure however). Anyway, they’re an astonishing sight by any standards, and it’s easy to understand why sailors have pictured them as humbugs. If you’re ever lucky enough to go to Antarctica, keep an eye out – you just might see one of these awesome wonders !

Picture sources 1 2 3 4 5 6 7

Warm summers cause extreme ice melting in Greenland

ice melting greenland
Recently a study was conducted by a team led by Dr Edward Hanna at the University of Sheffield which demonstrated that recent warm summers have caused the most extreme Greenland ice melting in 50 years. This is yet another proof of the damage caused by global warming and it also helps scientists place recent satellite observations of Greenland´s shrinking ice mass in a long term climatic context.

Dr Hanna of the University´s Department of Geography, alongside some of the World´s leading Greenland glaciologists and climatologists, analysed a combination of key meteorological and glaciological records spanning a number of decades as part of the research. The findings showed that the ice sheet of Greenland responded to regional climate from the 1960s to the early 1990s. But in the last fifteen years there has been a corespondence between global temperatures and the temperatures in Greenland, demonstrating Greenland´s recent response to global warming.

Especially the summer of 2003 played a crucial role in this melting and it was exceptionally warm around the margins of the Greenland Ice Sheet resulting in the second-highest meltwater from the Ice Sheet in the last 50 years. 2005 was also a very warm year and 2007 broke the record; it’s not something we should take great pride in.

The team of researchers includes some of the leading Greenland glaciologists and climatologists from the Free University of Brussels, University of Colorado, Danish Meteorological Institute and NASA Goddard Earth Science and Technology Center, University of Maryland Baltimore County, as well as four members of the University of Sheffield.
Dr Edward Hanna said:

“Our work shows that global warming is beginning to take its toll on the Greenland Ice Sheet which, as a relict feature of the last Ice Age, has already been living on borrowed time and seems now to be in inexorable decline. The question is can we reduce greenhouse-gas emissions in time to make enough of a difference to curb this decay?”