Search Results for Tag: glaciers
Greenland ice a speedy chute to rising seas?
As I checked through the news agencies to keep tabs on what’s been happening with Greenland as 2016 kicks off, the only agency piece I came across is a German story (on AFPD) on how climate change is apparently bringing the world’s biggest island an “economic upswing”. New fish species off the coast, better conditions for agriculture and exportable powdered rock from retreating glaciers are listed amongst the benefits.
No mention of a study published in Nature Climate Change this week showing that recent atmospheric warming – especially the exceptional summers in 2010 and 2012 – are reducing the ability of some layers of the giant ice sheet to store meltwater. That, in turn, can mean runoff is released into the ocean faster than previously assumed, rushing down a kind of icy chute. Clearly, this has considerable implications for global sea level rise.
Approximately half of Greenland’s current annual mass loss is attributed to runoff from surface melt. At higher elevations, the melt does not necessarily equal runoff, because meltwater can refreeze in the porous snow and firn near the surface. Horst Machguth from the Geological Survey of Denmark and Greenland, the lead author of the study, explains the background in a news release by CIRES, the Cooperative Institute for Research on Environment Sciences, Boulder Colorado: “The near-surface of the large ice sheet interior is comprised of snow that is slowly being converted into glacier ice. This porous firn layer can be up to 80 m thick,” he writes. Recent studies indicated that this firn is an important buffer against contributing to sea level rise for decades to come, because it absorbs and stores the meltwater like a sponge, refreezing it to form ice layers as it percolates down from the ice sheet surface. But the authors say the new study shows this may not be the case.
After the Greenland Ice Sheet was hit by a series of warm summers, it was unknown how the firn reacted to exceptional amounts of meltwater, says Machgut. The research aimed to clarify whether the firn was indeed capable of retaining the meltwater, or whether the sponge had been “overwhelmed” by all the extra water.
The scientists drilled cores to sample the firn at sites where similar cores had been drilled 15 to 20 years ago. They found that the amount of refrozen ice layers in the firn had increased substantially over the past two decades in many places, but not everywhere. Cores drilled at lower elevations suggested the recent exceptional meltwater amounts had only trickled through to shallow depths within the firn, conglomerating into massive ice layers directly below the ice sheet surface.
“It appears that the firn was overwhelmed by the melt to a degree where so many ice lenses had formed that they started to hinder percolation of further meltwater. Initially small ice lenses grew to form ice layers of several meters in thickness that act as a lid on top of otherwise sponge-like firn. Radar measurements identified that these massive ice lenses were continuous over tens of kilometres,” says Dirk van As, a co-author of the study from the Geological Survey. “Surface meltwater wants to refreeze in firn locally, which it does at higher elevation, but at lower elevations it hits that lid of ice and is forced to stay at the surface where it cumulates.”
Satellite images show that meltwater then formed rivers on the surface flowing towards the margin of the ice sheet.
More data required
“In contrast to storing meltwater in porous firn, this mechanism increases runoff from the ice sheet,” says CIRES researcher Mike MacFerrin, a second author on the study. “This process has not previously been observed in Greenland. The extent of this ice lid capping the ice sheet firn remains unknown. For this reason, the total amount of additional ice sheet runoff associated with this newly observed process cannot yet be quantified.”
The scientists are now combining their core data with radar measurements from NASA, which cover the entire ice sheet. They say similar changes in firn structure have been observed on various ice caps in the neighbouring Canadian Arctic, which indicates the phenomenon could be widespread in Greenland. Only west Greenland was covered by the new study.
The Greenland ice sheet is already a great concern, with the melting ice rate increasing continually as the atmosphere and the oceans warm. As well as contributing to rising sea levels, the increase in runoff from the ice sheet could also result in feedback processes which could lead to even more melt in the future. The water running down the ice sheet can create darker, slushy channels, the scientists say, which can reduce the albedo effect of the ice sheet, its ability to reflect sunlight away from its surface. As more sunlight is absorbed instead of being reflected off, the surface temperature could warm further.
Given the huge significance of the Greenland ice sheet in terms of global sea level rise and its role in the global climate system, the findings of this study deserve a little more attention than being confined to the publications of the scientific communities.
But maybe potatoes from the “ice island” and mackerel and tuna off its snow-tipped coasts make for more striking headlines?
DateJanuary 6, 2016 | 3:09 pm
TagsArctic, CIRES, Climate, firn, Geological Survey of Denmark and Greenland, glaciers, Greenland, ice, Machguth, meltwater, research, science, Sea level, snow, Warming
Can Paris avert climate threat to cryosphere?
To those of us who work on polar subjects, there is no question about the relevance of the cryosphere to the annual UN climate negotiations. But in the run-up to the annual mega-event – especially in a year dubbed by some to be the “last chance” for climate – it was not easy to get attention for the Arctic, Antarctic and high-altitude peaks and glaciers of the world.
I had a discussion with some of my colleagues who focus on Africa and Asia. With problems like political unrest, wars, famine and drought to cope with, the fate of polar bears, one told me, is completely irrelevant.
You could say this colleague is suffering from a kind of tunnel vision. But it also prompts me to wonder whether the way we communicate the threat of climate change is partly to blame.
Not just polar bears
Earlier this week I read about a study indicating that people were more likely to donate to campaigns which focus on people, on social injustice rather than on conservation and environmental degradation. Somehow, we journalists have to make the connection between the two. When you remind people that increasing sea levels caused to a large extent by changes in our ice sheets pose a huge threat not only to small island states but to many of the world’s megacities, the cryosphere takes on a new relevance. Not to mention the fact that the ice, snow and permafrost covered regions of our planet play a major role in regulating the world’s climate and water supplies.
One organization that works to bring the attention of delegates at the UN climate talks to our icy regions is the International Cryosphere Climate Initiative, ICCI. In time for this year’s COP21, it commissioned a report from leading scientists: “Thresholds and closing windows. Risks of irreversible cryosphere climate change”. The report summarizes the levels of risk in five key areas: ice sheets loss and related sea-level rise, polar ocean acidification, land glacier loss, permafrost melt, and the loss of Arctic summer sea ice. The report is based on the last IPCC assessment plus literature published in the three years since.
Bringing the ice closer
Pam Pearson is the director and founder of ICCI. I have interviewed her on various occasions, including during visits she made to Bonn, the home of the UNFCCC, to brief delegates. This time we were not able to meet in person, but we have been in Email contact. I asked her how difficult it was to arouse interest within the negotiations at the moment, with so much going on. She told me it was difficult mainly because very few people globally actually live near cryosphere.
“Yet we are all deeply connected to these regions, because of their role in the Earth climate system — especially through sea-level rise, water resources from land glaciers, and permafrost release that will make it harder to meet carbon budgets. “
The Arctic, parts of Antarctica and many mountain regions have already warmed two to three times faster than the rest of the planet, between 2 and 3.5 degrees Celsius up on pre-industrial levels. Climate change is also affecting high altitude areas such as the Himalayas and the Andes, where seasonal glacier melt provides water for drinking and irrigation, especially in dry periods.
When the outside risk becomes the norm
The changes are far more extreme than those forecast in even the most pessimistic scenarios of a few years ago. In the IPCC’s 2007 Fourth Assessment, the outer extreme estimate for sea level rise (mostly from glacier ice melt) was about one meter by the end of this century. Today, the experts say even if we could halt warming now, it would be impossible to avoid sea-level rise of one meter from glaciers, ice sheets and the natural expansion of warming waters, within the next two hundred years. Most scientists also agree that the West Antarctic ice sheet has already been destabilized by warming to the extent where this probably cannot be halted, which will increase sea level further.
Pearson used to be a climate negotiator herself, so she knows the pressures and constraints. She told me that while participants in the climate conferences were broadly aware of issues like ice melt at the poles and on high-altitude glaciers, they tended to lack awareness of two key aspects:
“First, that we have already passed, or are close to passing temperature levels that will cause certain processes to begin; and second, that some of these processes cannot be stopped once they get started.”
She says a “sense of urgency” is lacking, and stresses that although some of the most damaging consequences will only occur in hundreds or even thousands of years, they will be determined by our actions or inactions in the coming few decades. That includes the 2020-30 commitment period that is the focus of the agreement being worked on in Paris Pearson stresses.
The cryosphere needs more ambitious targets
The report analyses the implications of the INDCs, or current pledges put on the table by the countries of the world for the Paris climate talks. The scientists come to the conclusion that these will not be enough to prevent the onset of many irreversible cryosphere processes.
Even the two-degree pathway agreed by the international community translates into a peak cryosphere temperature of between 4 and 7 degrees above pre-industrial levels, according to the ice experts. Yet the UN and others say current commitments would lead to global temperatures 2.7 to 3.5 degrees Celsius above pre-industrial levels by 2100, rising later to between 3.4 and 4.2 degrees. The peak in global carbon emissions would occur well after 2050. The associated temperatures would trigger permanent changes in our ice and snow that cannot be reversed, including the complete loss of most mountain glaciers, the complete loss of portions of West Antarctica’s Ice Sheets and parts of Greenland. This would ultimately equate to an unstoppable sea level rise of a minimum four to ten meters, the scientists find.
In addition, the increase of CO2 being absorbed in the Southern Ocean around Antarctica and the Arctic Ocean is turning the water more acidic and so threatening fisheries, marine ecosystems and species.
Another of the key issues which is often neglected is that of permafrost. About a quarter of the Northern Hemisphere’s land area contains ground that remains frozen throughout the year. This holds vast amounts of ancient organic carbon. So when it thaws, carbon dioxide and methane are released, which fuel further warming. Even a temperature rise of 1.5 degrees could result in a 30% loss of near-surface permafrost. This would mean 50 Gigatonnes of additional carbon emissions by 2100. Given that the total carbon budget allocated to a two-degree temperature rise is only 275 Gigatonnes, that would be a huge factor. The ICCI experts say this thaw would not be reversible, except on geological time scales.
Dwindling Arctic sea ice
Arctic summer sea ice has declined rapidly, especially since 2000. Only about half the sea ice survives the summer today compared to 1950. This is “both a result and a cause of overall Arctic and global warming”, according to the ICCI report. White ice reflects heat into space. When it melts, it is replaced by dark water, which absorbs the heat, exacerbating warming further.
The Arctic sea ice has a tempering effect on global temperatures and weather patterns. It would only be possible to reverse the disappearance of the ice in summer with a return to regular global temperatures of 1 to 2 degrees above pre-industrial times, according to the report.
Andes and Himalayas
Receding mountain glaciers in the European Alps, American Rockies, Andes and East Africa were among the first identified, visible impacts of climate change, originally from natural factors. Sometime in the past 50 years, anthropogenic climate change surpassed natural warming as the main driver of retreat, and caused about two-thirds of glacier melt between 1991 and 2010, according to the ICCI report.
Glaciers are important to nearby communities as a source of water for drinking or irrigation. Some are especially important in dry seasons, heat waves and droughts. Melting glaciers provide an increase in water for a limited time. But ultimately, the lack of water could make traditional agriculture impossible in some regions of the Himalayas or the Andes.
So unless governments in Paris move fast to increase their commitments and bring the deadlines for emissions reductions forward, the windows to prevent some of these irreversible impacts on the polar and high mountain regions may close during the 2020-2030 commitment period.
It is not too late
However, the scientists stress that it is still possible to reduce emissions to the required level, if the political will becomes strong enough. Pam Pearson says the world has to get onto the path towards the two-degree goal now. Like many experts, she says this in itself is risky enough for the cryosphere, and a 1.5 degree pathway would be safer:
“So if countries indeed agree with UNFCCC chief Christiana Figueres’ proposal to meet every five years to strengthen INDCs, moving onto these lower-temperature pathways should be a concrete goal. Perhaps even more important, I understand the French COP presidency may be aiming at strengthening actions PRIOR to 2020, in the 2015-2020 period. This kind of earlier action is really vital, and will make the job of keeping temperatures as low as possible easier”
Without much more ambitious targets, the ICCI study concludes it will be “close to impossible” to avoid rapid deterioration of our snow and ice regions.
The challenge is to make the delegates in Paris understand that that does not just mean cosmetic changes to distant parts of the globe, but that it would also destabilize the global climate, displace millions of people and endanger food and water supplies in many parts of the world.
DateDecember 1, 2015 | 3:00 pm
TagsAntarctic, Arctic, Climate, CO2, COP21, Emissions, glaciers, Greenland, ice, Media, ocean acidification, Paris, polar bears, science, Sea level, snow, UN talks
Energy giant taken to German court for glacier melt
For the first time ever in Europe, a company is being sued for causing climate change.
Essen, in Germany’s famous Ruhr area, once the centre of the country’s industrial development, is the scene of a very interesting court hearing today. A Peruvian smallholder and mountain guide Saúl Luciano Lliuya is suing the German energy concern RWE. He says the enormous amounts of greenhouse gases emitted by the company are jeopardizing his family, his property and a large area of his home town, Huaraz. A lake which is growing rapidly as climate warming melts the glaciers above, is posing a major risk for the town in the Andes and its 120,000 residents.
The ngo Germanwatch, which works to end the north-south divide and is particularly active in advocating climate justice, is advising the farmer from Peru and supporting the court case, which is unprecedented here in Europe and sends out a key signal just days ahead of the Paris COP21.
LLiuya says Huaraz is at risk from flooding. He and his lawyer Dr. Roda Verheyen argue that the Essen-based company is to a large degree responsible for the melting of glaciers in the Andes, and so for the risk to his home, which is located in the valley below.
They want RWE to contribute to the funding of protective measures for the town. And they argue that the energy company’s share should be in line with the amount of responsibility it bears for causing global warming. If the claimants can prove their case, that would presumably be rather a large share.
“Every day I see the glaciers melting and the lakes in the mountains growing”, says Lliuya, in a statement published by Germanwatch. “For us in the valley, this is a huge threat. We can’t just wait and see what happens. For me it is clear that those who are causing climate change should be held responsible: companies all over the world, that change the climate with their greenhouse gas emissions”.
A test case to watch
Luciano Lliuya’s lawyer, Dr. Roday Verheyen, told journalists the case was a test case, without precedent: “ RWE emits especially through its coal-fired power stations. These emissions result in rising temperatures worldwide, melting glaciers and so jeopardize the property of my client”, she said in a statement distributed by Germanwatch. She appealed to the court to assert that RWE bears responsibility for counter-measures.
In late April, the company rejected a claim submitted directly to them.
The idea that climate change is responsible for the melting of glaciers will come as no surprise to Iceblog readers. The IPCC clearly makes the connection. But attributing the cause and financial responsibility to an energy company is not so easy, hence the significance of this case.
In the shadow of a melting ice giant
The town of Huaraz in Peru lies a few kilometres below the Palcacocha glacier lake. Since 2003, it has grown four times as big as it was before. Climate change is also increasing the risk of giant blocks of ice breaking off and tumbling into the lake. That could cause a catastrophic flood wave and metre-high flooding of the settlements below.
The authority responsible for civil protection has warned that this could happen at any moment. It says this is the most dangerous glacial lake in the region. To provide lasting protection against this risk, a new system would have to be built to continually pump off large amounts of water. New barriers would also have to be built around the lake.
A message to Paris
The chairman of Germanwatch, Klaus Milke, stressed the importance of the court case as a signal to the energy sector and the world’s politicians in the run-up to the UN climate conference in Paris.
“Emissions have to drop, so that we do not have an ever-increasing number of people put at risk by climate change. And those who cause these risks must bear the cost of protecting the people affected”, he told journalists.
He stressed it could not be left to individual victims of climate change – who are often very poor – to go to court for assistance:“Ultimately, we need a political solution, to make those who caused the damage take on the responsibility”, Milke added.
According to Germanwatch, RWE describes itself as the biggest single emitter of CO2 in Europe. A survey conducted in 2014 says the concern is responsible for around half a percent of all the greenhouse gas emissions worldwide since the industrial revolution. Although the company is still just one of many responsible for CO2 emissions, Saúl Luciano Lliuya is claiming the company for a “fair share” of the cost of measures to protect his town, around 20,000 euro. This is probably “peanuts” to a global operator like RWE, but it would be an important step. It would involve accepting responsibility for the impacts of emissions-induced climate change, and have potentially huge financial implications.
An interesting one to watch. Will this smallholder from Peru set the ball rolling which could knock the Goliath that is the global energy industry reeling?
DateNovember 24, 2015 | 1:42 pm
TagsAndes, Climate, Emissions, enrgy, fossil fuels, Germanwatch, glaciers, ice, Peru, RWE, UN talks, Warming
Melting glacier risk to seabed ecosystem
On my first visit to the Arctic in 2007, I went out into the Kongsfjord at Ny Alesund, Spitsbergen, with some marine biologists working out of Koldewey station, run jointly by France and Germany. It was June, and the glaciers at the end of the fjord were just starting to thaw. While I was enjoying the blues, whites and greys of the sea, ice and sky, the researchers in the small boat got very excited when they saw the water turned brown, where sediment was flowing into the fjord from the retreating glacier.
“Who turned off the light up there”?
They had been waiting impatiently for the thaw to set in, because their research focus was on what that means for the life forms on the seabed, or benthos. Clearly, if you live down on the sea floor, the intrusion of brown mud and other sediment changes your surroundings. Not least, it means less light coming down from above. Now while a certain amount of that is going to happen naturally every year with the changing seasons, the question is: what happens if there is a big increase in sediment coming in because of increasing melt through climate change?
I was interested to hear about a study published this week in Science Advances, dealing with that same question in the Antarctic. The findings indicate that melting coastal glaciers are having an impact on the entire ecosystem on the seafloor, leading to a loss of biodiversity through sedimentation. The scientists were looking at the West Antarctic peninsula, where the temperature has risen almost five times faster than the global average in the last fifty years.
Global warming changes seafloor communities
The study, published by experts from Argentina, Germany and Great Britain, including the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI,) is based on repeated research dives. The scientists believe increased levels of suspended sediment in the water caused the dwindling biodiversity registered in the coastal region. They say it occurs when the effects of global warming lead glaciers near the coast to begin melting, discharging large quantities of sediment into the seawater.
To find out exactly how and to what extent the retreat of glaciers is affecting bottom-dwelling organisms, researchers at the Dallmann Laboratory are now mapping and analysing the benthos in Potter Cove, located on King George Island off the western Antarctic Peninsula. The lab is operated by the Alfred Wegener Institute and the Argentine Antarctic Institute (IAA) as part of the Argentinian Carlini Station. Researchers have been monitoring benthic flora and fauna there for more than two decades.
In 1998, 2004 and 2010, divers photographed the species communities at three different points and at different water depths: the first, near the glacier’s edge; the second, an area less directly influenced by the glacier; and the third, in the cove’s minimally affected outer edge. They also recorded the sedimentation rates, water temperatures and other oceanographic parameters at the respective stations, so that they could correlate the biological data with these values. Their findings: some species are extremely sensitive to higher sedimentation rates.
Short sea squirts adapt better
Sea squirts are small invertebrate creatures that live on the sea floor and feed by filtering the water through their anatomies.
“Particularly tall-growing ascidians like some previously dominant sea squirt species can’t adapt to the changed conditions and die out, while their shorter relatives can readily accommodate the cloudy water and sediment cover,” says Dr Doris Abele, an AWI biologist and co-author of the study. She is worried that “the loss of important species is changing the coastal ecosystems and their highly productive food webs, and we still can’t predict the long-term consequences.”
As with so many aspects of our oceans, there is a lack of base data on how sediment from melting glaciers affects the numerous life forms on the seabed.
“It was essential to have a basis of initial data, which we could use for comparison with the changes. In the Southern Ocean we began this work comparatively late,” says the study’s first author, marine ecologist Ricardo Sahade from the University of Cordoba and Argentina’s National Scientific and Technical Research Council CONICET, who is leading the benthic long-term series. “Combining this series of observations, accompanying ecological research on important Antarctic species, and mathematical modelling allows us to forecast the changes to the ecosystem in future scenarios,” says co-author Fernando Momo from Argentina’s National University of General Sarmiento.
With scientists telling us the ice of the West Antarctic peninsula has already passed a tipping point, the question is whether scientific monitoring and research will be able to keep pace with the rapid rate at which climate warming is already having major impacts on our oceans. For many species of our seabottom-dwelling creatures, the slow pace of greenhouse gas emissions reductions may well come far too late.
See also: Antarctic glaciers retreat unstoppable
DateNovember 13, 2015 | 8:29 pm
Polar melt confirmed from space
I am disappointed that there was so little mainstream media coverage (please correct me if I am wrong) of a report from a team of scientists from Germany’s Alfred Wegener Institute (AWI) in Bremerhaven who have analysed just over two years of data from the CryoSat-2 satellite. Their conclusion that the Greenland ice sheet and Antarctica’s glaciers are melting at record pace, dumping some 500 cubic kilometers of ice into the oceans every year, twice as much in the case of Greenland and three times as much in the case of Antarctica, by comparison with 2009 – yes, you read right, we are talking about a very short period for such a dramatic increase in ice loss – should have made more news headlines and not just the science pages.
To understand the scale of that, the researchers say it would be the equivalent of an ice sheet that’s 600 meters thick and covers an area as big as the German city of Hamburg – or, my colleagues here at DW calculate, as big as Singapore.
The research team headed by Veit Helm used around two years’ worth of data from the ESA CryoSat-2 satellite to create digital elevation models of Greenland and Antarctica. The results were published in the online magazine of the European Geoscience Union (EGU) The Cryosphere.
“The new elevation maps are snapshots of the current state of the ice sheets,” Helm says. “The elevations are very accurate, to just a few meters in height, and cover close to 16 million square kilometers of the area of the ice sheets.” He says this includes an additional 500,000 square kilometers that weren’t covered in previous elevation models from altimetry.
Space technology shows declining ice mass
Helm and his team analyzed all data from the CryoSat-2 radar altimeter SIRAL in order to come up with the detailed maps. The satellite with this new radar equipment was launched in 2010. Satellite altimeters measure the height of an ice sheet by sending radar or laser pulses which are then reflected by the surface of the glaciers or surrounding areas of water and recorded by the satellite.
The researchers used other satellite data as well to document how elevation has changed between 2011 and 2014.
Rapid ice loss over a short period of time
The team used more than 200 million SIRAL data points for Antarctica and some 14 million data points for Greenland to create the elevation maps. The results show that Greenland alone is losing around 375 cubic kilometers of ice per year.
Compared to data which was collected in 2009, the loss of mass from the Greenland ice sheet has doubled. The rate of ice discharge from the West Antarctic ice sheet tripled during the same period.
I think this is definitely worth talking about. We know the huge implications of polar ice melt for global sea levels. Other research from this year also tells us that, at least in the case of parts of Antarctica, the ice melt is probably irreversible.
We cannot afford to ignore what is happening to the ice sheets. The extent of ice loss in Greenland is particularly dramatic. I am losing patience with those people who respond to studies like this and our reporting on it by saying “but the East Antarctic is gaining volume” and “the Antarctic sea ice has grown”. It is so easy to take things out of context and mix different factors up when trying to understand a very complex system.
I will give the last word here to AWI glaciologist Angelika Humbert, who co-authored the study: “If you combine the two ice sheets (Greenland and Antarctic), they are thinning at a rate of 500 cubic kilometers per year. That is the highest rate observed since altimetry satellite records began about 20 years ago.” It seems to me there is no arguing with that.
DateAugust 22, 2014 | 1:33 pm