6 Search Results for: Duarte
Arctic sea ice, Greenland and Europe’s weird weather
As I write this, I am sitting in a short-sleeved shirt with the window open, enjoying an unusually warm start to the month of May. It’s around 27 degrees Celsius in this part of Germany, pleasant, but somewhat unusual at this time. The first four months of this year have been the hottest of any year on record, according to satellite data.
The Arctic is not the first place people tend to think of when it comes to explaining weather that is warmer – as opposed to colder – than usual in other parts of the globe. But several recent studies have increased the evidence that what is happening in the far North is playing a key role in creating unusual weather patterns further south – and that includes heat, at times.
Why sea ice matters
The Arctic has been known for a long time to be warming at least twice as fast as the earth as a whole. As discussed here on the Ice Blog, the past winter was a record one for the Arctic, including its sea ice. The winter sea ice cover reached a record low. Some scientists say the prerequisites are in place for 2016 to see the lowest sea ice extent ever.
Several recent studies have increased the evidence that these variations in the Arctic sea ice cover are strongly linked to the accelerating loss of Greenland’s land ice, and to extreme weather in North America an Europe.
“Has Arctic Sea Ice Loss Contributed to Increased Surface Melting of the Greenland Ice Sheet”, by Liu, Francis et.al, published in the journal of the American Meteorological Society, comes to the conclusion: “Reduced summer sea ice favors stronger and more frequent occurrences of blocking-high pressure events over Greenland.” The thesis is that the lack of summer sea ice (and resulting warming of the ocean, as the white cover which insulates it and reflects heat back into space disappears and is replaced by a darker surface that absorbs more heat) increases occurrences of high pressure systems which get “ stuck and act like a brick wall, “blocking” the weather from changing”, as Joe Romm puts it in an article on “Climate Progress”.
Everything is connected
The study abstract says the researchers found “a positive feedback between the variability in the extent of summer Arctic sea ice and melt area of the summer Greenland ice sheet, which affects the Greenland ice sheet mass balance”. As Romm sums it up:“that’s why we have been seeing both more blocking events over Greenland and faster ice melt.”
He quotes co-author Jennifer Francis of Rutgers University, New Jersey, explaining how these “blocks” can lead to additional surface melt on the Greenland ice sheet, as well as “persistent weather patterns both upstream (North America) and downstream (Europe) of the block.
“Persistent weather can result in extreme events, such as prolonged heat waves, flooding, and droughts, all of which have repeatedly reared their heads more frequently in recent years”, Romm concludes.
“Greenland melt linked to weird weather in Europe and USA” is the headline of an article by Catherine Jex in Science Nordic. People are usually interested in changes in the Greenland ice sheet because of its importance for global sea level, which could rise by around seven metres if it were to melt completely. But Jex also draws attention to the significance of changes to the Greenland ice for the Earth’s climate system as a whole.
The jet stream
“Some scientists think that we are already witnessing the effects of a warmer Arctic by way of changes to the polar jet stream. While an ice-free Arctic Ocean could have big impacts to weather throughout the US and Europe by the end of this century”.
She also notes some scientists warning of “superstorms”, if melt water from Greenland were eventually to shut down ocean circulation in the North Atlantic.
The site contains an interactive map to indicate how changes in Greenland and the Arctic could be driving changes in global climate and environment.
The jet streams drive weather systems in a west-east direction in the northern hemisphere. They are influenced by the difference in temperature between cold Arctic air and warmer mid-latitudes. With the Arctic warming faster than the rest of the planet, this temperature contrast is shrinking, and scientists say the jet streams are weakening.
Jex quotes meteorologist Michael Tjernström, from Stockholm University, Sweden: “Climatology of the last five years shows that the jet has weakened,” says. Its effect on weather around the world is a hot topic.
“We’ve had strange weather for a couple of years. But it’s difficult to say exactly why.”
One explanation, Jex writes, is that a weak jet stream meanders in great loops, which can bring extremes in either cold dry polar air or warmer wetter air from the south, depending on which side of the loop you find yourself. If the jet stream gets “stuck” in this kind of configuration, these extreme conditions can persist for days or even weeks.
Experts have attributed extreme events like the record cold on the east coast of the USA in early 2015, a record warm winter later the same year, and the summer heat waves and mild wet winters with exceptional flooding in the UK to these kind of “kinks” in the jet stream.
Greenland and the ocean
The changes to Greenland’s vast land ice sheet also have consequences for ocean circulation, because they mean an influx of the cold fresh water flowing into the salty sea. And the sea off the east coast of Greenland plays a key role in the movement of water, transporting heat to different parts of the world’s oceans and influencing atmospheric circulation and weather systems.
There have often been “catastrophe scenarios” suggesting the Gulf Steam, which brings warm water and weather from the tropics to the USA and Europe could ultimately be halted, leading to a new ice age. (Remember the “Day after Tomorrow?)
Although this extreme scenario is currently considered unlikely, research does suggest that the major influx of fresh water from melting ice in Greenland and other parts of the Arctic could slow the circulation and result in cooler temperatures in north western Europe.
Jex goes into the theory of a “cold blob” of ocean just south of Greenland, where melt water from the ice sheet accumulates. Some scientists say this indicates that ocean circulation is already slowing down. The “blob” appeared in global temperature maps in 2014. While the rest of the world saw record breaking warm temperatures, this patch of ocean remained unusually cold.
According to a recent study led by James Hansen, from Columbia University, USA, the ‘cold blob’ could become a permanent feature of the North Atlantic by the middle of this century. Hansen and his colleagues claim that a persistent ‘cold blob’ and a full shut down of North Atlantic Ocean circulation could lead to so-called ‘superstorms’ throughout the Atlantic. And there is geological evidence that this has happened before, they say. But the paper was controversial and many climate scientists questioned the strength of the evidence.
However, some scientists already attribute western Europe’s warm and wet winter of 2015 to the “cold blob”, Jex notes, which may have altered the strength and direction of storms via the jet stream.
The good old British weather
The UK’s Independent goes into a new study by researchers at Sheffield University, which indicates soaring temperatures in Greenland are causing storms and floods in Britain. The Independent’s author Ian Johnston says the study “provides further evidence climate change is already happening”.
It never ceases to amaze me that evidence is still being sought for that, but, clearly, there are still those who are yet to be convinced our human behavior is changing the world’s climate. So every bit of scientific evidence helps – especially if it relates to that all-time favourite topic of the weather.
The study also looks at the static areas of high pressure blocking the jet stream. With amazing temperature rises of up to ten degrees Celsius during winter on the west coast of Greenland in just two decades, it is not hard to imagine how this can effect the jet stream, and so our weather in the northern hemisphere.” If forced to go south, the jet stream picks up warm and wet air – and Britain can expect heavy rain and flooding. If forced north, the UK is likely to be hit by cold air from the Arctic”, Johnston writes.
The article quotes Professor Edward Hanna from the University of Sheffield, lead author of a paper about the research published in the International Journal of Climatology, and says seven of the strongest 11 blocking effects in the last 165 years had taken place since 2007, resulting in unusually wet weather in the UK in the summers of 2007 and 2012.
Hanna told the Independent computer models used 10 to 15 years ago to predict the extent of sea ice in the Arctic had significantly underestimated how quickly the region would warm.
“It’s very interesting to look at the observed changes in the Arctic … the actual observations are showing far more dramatic changes than the computer models,” Professor Hanna said.
“You do get sudden starts and jumps. It’s the sudden changes that can take us by surprise and there certainly does seem to have been an increase in extreme weather in certain places.”
Drawing conclusions (or not?)
In the Washington Post, (reprinted on Alaska Dispatch News) Chelsea Harvey sums up the conclusions of the latest research in an article entitled “Dominoes fall: Vanishing Arctic ice shifts jet stream, which melts Greenland glaciers”:
“There are a more complex set of variables affecting the ice sheet than experts had imagined. A recent set of scientific papers have proposed a critical connection between sharp declines in Arctic sea ice and changes in the atmosphere, which they say are not only affecting ice melt in Greenland, but also weather patterns all over the North Atlantic”.
So what do we learn from all of this? Sometimes I ask myself how many times we have to hear a message before we really take it in and decide to do something about it.
Here in Bonn, not far from the office where I am sitting now, the first round of UN climate talks since the Paris Agreement at the end of last year will be kicking off this coming weekend. The aim is to stop the rise in global temperature from going about two, preferably 1.5 degrees C. We have already passed the one degree mark. In an interview with the Guardian this week, the head of the IPCC Hoesung Lee says it is still possible to keep below two degrees, although the costs could be “phenomenal”. But many scientists and other experts are increasingly dubious about whether emissions can really peak in time to achieve the goal. Current commitments by countries to emissions reductions still leave us on the track for three degrees at least.
The concentration of greenhouse gases in the atmosphere is, as the Guardian puts it, “teetering on the brink of no return”, which the landmark 400 ppm measured for the first time at the Australian station at Cape Grim and unlikely to go below the mark again at the Mauna Loa station in Hawaii.
On my desk, I have a book entitled “Arctic Tipping Points”, by Carlos M. Duarte and Paul Wassmann. It was published in 2011. Before that, Professor Duarte had explained the global significance of what is happening in the Arctic to me
at an Arctic Frontiers conference in Tromso, Norway. How much more evidence do we need? Science takes a long time to research, evaluate and publish solid evidence of change and its consequences, with complex review processes. If politicians delay much longer, the pace of climate change will be so fast that action to avert the worst cannot keep up. Meanwhile, that Arctic ice keeps dwindling – and I sense another major storm on the approach.
DateMay 12, 2016 | 11:53 am
TagsADN, AMS, Arctic, Arctic Frontiers, Bonn, Climate, cold blob, Duarte, Emissions, Greenland, Guardian, ice, Independent, International Journal of Climatology, James Hansen, research, Rutgers, science, sea ice, Sea level, Sheffield, tipping point, Tromso, UN talks, UNFCCC, warmest year, Warming
Polar ice tipping points
As I get ready to head up to Tromso for the Arctic Frontiers conference and prepare my accreditation for the next routine round of climate talks here in Bonn in March, I find myself with plenty of food for thought.
It seems like not that long ago that scientists were telling us that although the Arctic is clearly melting fast, there was no need to worry about the Antarctic ice melting. But for the past 15 years or so, scientists have been observing that glaciers in West Antarctica are out of balance. Ice shelves have been breaking off and the calving fronts of glaciers have been retreating, draining huge amounts of ice into the ocean. This week I was interested and concerned to read about the results of a modelling effort, using 3 different types of model, indicating a key Antarctic glacier was melting irreversibly.
(Map courtesy of Deutsche Welle)
The Pine Island Glacier in the Antarctic hit the headlines last year when a giant iceberg broke off it. It is a key glacier because it is actually responsible for some 20 percent of the total ice loss from the region. Now scientists have found the glacier is melting irreversibly – with dramatic consequences for global sea levels. For an article for DW entitled Antarctic’s glacier retreat unstoppable, I interviewed Gael Durand of the French University of Grenoble, one of a team of scientists who have just published the new study: “We show that the Pine Island Glacier will continue to retreat and that this retreat is self-sustaining. That means it is no longer dictated by changes in the ocean or the atmosphere, but is an internal, dynamic process”, Durand told me. This will mean an increasing discharge of ice and a greater contribution to global sea level rise. “It was estimated at around 20 gigatons per year during the last decade, and that will probably increase by a factor of three or five in the coming decade. That means this glacier alone should contribute to the sea level by 3.5 to 10 millimetres a year, accumulating to up to one centimetre sea rise over the next 20 years. For one glacier, that is colossal”, says Durand.
I called up Angelika Humbert from Germany’s Alfred Wegener Institute for Polar and Marine Research (AWI) to get an expert opinion on the significance of the new research. She told me 1cm over 20 years would be an “extremely high” amount. The glaciologist, who is also working on models for the Pine Island Glacier, stresses that all models include a degree of abstraction and uncertainty. However, her work also indicates that the glacier will make an increasing contribution to sea level rise in the coming years and describes the new study as a “considerable advance on the results of research to date.” Humbert says the results could well be applied to other glaciers of the same type.
Durand’s new study shows that the glacier is now flowing at a rate and in a way that makes the process irreversible. Even if the air and ocean temperatures cooled off to what they were a hundred years ago – which is in no way likely – Durand is convinced the glacier would not recover. Durand says the study should arouse concern because the glacier has passed a “tipping point”, a much discussed concept in climate science. “That means because of our behaviour, our climate is changing and will continue to change a lot. I think it is one of the first times we are passing these tipping points.”
The scientist compares the situation to that of a cyclist coming down from the top of a mountain and unable to brake: “We have to fear that the retreat will continue, that other glaciers in the region will start to do the same, and that we will have a collapse of this part of the ice shelf. That would take centuries, but it would mean a rise of several metres in sea level.”
The last report by the Intergovernmental Panel on climate Change (IPCC) warned of the implications if the glaciers of West Antarctica were to become unstable. “Here,” says Durand, “we have proof that that is already happening with this one.”
At the Arctic Frontiers conference two years back, I heard a lot of interesting discussions about climate tipping points. Professor Carlos Duarte Directorof the Oceans Institute at The University of Western Australia and Research Professor with the Spanish National Research Council (CSIC) talked to me at length about tipping points. Let me quote him briefly:
“Tipping Points – or thresholds – are levels of pressures beyond which small response of a property of interest becomes abrupt. Once a system or ecosystem or earth system crosses beyond a threshold, the changes, e.g. in the extent of ice or rate of warming, accelerate greatly, and once the threshold is crossed, it is sometimes very difficult to return to the original state even if pressure is released or reduced.”
We discussed the possible tipping points and warning signs outlined in a key piece of research by Timothy Lenton and others. Some would argue that tipping points have already been crossed in the Arctic region, which is known to be warming at least twice as fast as the rest of the earth. One of Lenton’s other key factors is the West Antarctic ice sheet becoming unstable. Now the “eternal ice” down south could be reaching a kind of “tipping point” in places. Yes, I know this only applies to a particular region of the West Antarctic, but the implications of irreversible glacier melt there are already huge. Greenland and that West Anarctic ice sheet play a key role in storing masses of fresh water, which would have huge implications if they melted. With marine glaciers, like the Pine Island Glaciers, the melt of white ice to expose more dark ocean surface underneath would further increase warming by absorbing solar heat instead of reflecting it back.
With the EU in the news today for considering moving away from binding climate targets, and little progress in sight towards an effective new climate agreement scheduled to be agreed in Paris in 2015, this all puts me in a pensive mood, as I get ready to head north and focus on the implications of the changing climate for “Humans in the Arctic”.
DateJanuary 16, 2014 | 1:37 pm
TagsAntarctic, Arctic, Arctic Frontiers, AWI, Climate, EU, glaciers, Pine Island Glacier, Tromso, UN talks
Arctic melt worries UN and White House
The UN weather agency WMO (World Meteorological Organisation) has confirmed that the Arctic’s sea ice melted at a record pace in 2012, the ninth-hottest year on record. With just 3.4 million square kilometres (1.32 million square miles) during the August to September melting season, the sea ice cover was a full 18 percent less than the previous low set in 2007. The WMO’s Secretary-General Michel Jarraud said this was a “disturbing sign of climate change”, and pointed to the link between climate change and extreme weather events.
Meanwhile, a special briefing was called at the White House to discuss the possibility of the Arctic becoming ice free in the summer within just TWO years. Nafeed Ahmed, director of the “Institute for Policy Research & Development” headlines his post for the “Guardian“: “White House warned on imminent Arctic ice death spiral”. He describes the meeting, including NASA’s acting chief scientist Gale Allen, the director of the Department of Homeland Security and the Pentagon as “the latest indication that US officials are increasingly concerned about the international and domestic security implications of climate change”.
10 Arctic specialists were called in to advise the US government, including marine scientist Professor Carlos Duarte, currently director of the Oceans Institute at the University of Western Australia. I met and interviewed Prof. Duarte back in 2011 at the Arctic Frontiers conference, when he worked with the Spanish Council for Scientific Research. At that time, he was already calling for urgent action and warning of the danger of “climate tipping points”, including the melt of the Arctic sea ice. His conclusions are based on research which was presented in an article in Nature Climate Change last year.
The West Australian newspaper quotes Prof. Duarte as saying the “snowballing situation would prove as hard to slow down as a runaway train”. He told the paper the ice melt was accelerating faster than any of the models could predict, and the prospect of an Arctic Ocean free of ice had been brought forward to 2015, compared with a prediction in 2007 that at least a third of the normal sea ice extent would remain in summer in 2100. When I spoke to him in 2011, the US navy was already assuming a date of 2050 and Duarte said he expected it to be even earlier.
Prof Duarte also warned of the increasing danger of melting methane. Let me quote a little from the interview:
DUARTE: “We know from the history of ice covering the planet along geological time scales that ice is strongly a non-linear element in the earth’s system. It’s one of the components that show very rapid, very abrupt changes and tipping points. So we expect that once the ice will be lost quickly from the Arctic and also from the shelves in Greenland, then other forces will be set in motion, and many forces will be set in motion by loss of ice. One of them is the release of methane hydrates from the shallow continental shelves, mostly around Siberia, and those are molecules of methane that are trapped into ice in the sediments of the continental shelves and in the permafrost on land. So if this ice melts, this methane can be released abruptly and suddenly. And deposits of methane trapped in the shallow sediments of the Arctic amount to about five times the greenhouse power that humans have set in motion through burning fossil fuels. So if this five times what we have released in 150 years is released within a few years, that would be detrimental to the climate system and it could lead to a very rapid warming, and could again set in motion other forces like increased freshwater discharge to the Arctic, which has already increased by 30 percent. And this involves a greater export of fresh water and buoyancy to the Atlantic, which may affect global circulation and global currents, and those in turn will affect regional climates also further south to the sub-Arctic region. Also, warmer temperatures are leading to dieback of the boreal forest and also the peat deposits in the boreal region are drying up to the extent that they can catch fire.”
(IRENE QUAILE: How close are we?)
DUARTE: “We very much know what the threshold and the tipping point for the release of methanes will be, because the methane is kept in the hydrates, deposits in the salty sediments by ice, frozen sediments, and we know the freezing point of salty sediments may be around minus 1 degree. So when the temperature of water in the summer goes well above freezing point, the hydrates will defrost and the methane will be released. So what we need to monitor is the temperature of the shallow waters in the Siberian shelf and other shallow waters in the Arctic, in the Canadian region as well, and see how close they’re getting to temperatures of 3 and 4 degrees, which will be those that will lead to melting of the hydrates.”
Scary? The interview, it seems, is as relevant as ever, the Professor’s warnings more urgent. I wonder what it feels like to be called in to the White House to brief the government of a country that is both a key player in the Arctic and a top emitter of the greenhouse gases that are causing the melt? On the one hand it must be satisfying for the scientists to know they are finally being heard. But there must also be some frustration about the extent of dangerous climate change that had to be set in motion first. Has the Arctic ice already reached a “tipping point”?
Let me close with another quote from that interview with Carlos Duarte:
DUARTE: “Unfortunately society is much more mobilised by opportunities than by risks. So the discourses and warnings of risks actually almost lead to inaction by society, whereas the sight of opportunities encourages society to set themselves in motion. So the opportunities for economic growth in the Arctic have dominated the discourse and the actions by society and policy makers. Those opportunities are new navigation routes across the Arctic, and the exploitation of oil, gas and fisheries, that were not accessible just a few years ago. The paradox in this is that the Arctic countries recognise that the forces that are improving access to these resources is actually climate change and that the reason for this climate change is the burning of fossil fuels by humans. Arctic nations themselves are responsible for 26% of the release of these greenhouse gases and are taking advantage of these opportunities, which will involve greater emissions of greenhouse gases. (…) I think there should be a balance between the economic growth these opportunities could bring about and the economic losses, they may bring about, which I don’t think have been quantified.”
DateMay 6, 2013 | 1:54 pm
Chernobyl , Fukushima and “climate-friendly” energy
It’s hard to concentrate on other things with a potentially major nuclear catastrophe on the horizon in Japan. I interviewed the head of a Greenpeace team of experts who were in Chernobyl looking into the lasting after-effects of the disaster 25 years ago when the news started to come in from Japan. She described the looks on people’s faces as they heard it and says their expressions told her “we know what that area of Japan will look like in 25 years time.” Deformed children, contaminated foodstuffs…
You would think this latest disaster would really put governments off nuclear power, which of course the pro-atomic lobby has been selling as “climate-friendly”. Germany’s current government had upturned the previous government’s momentous decision to phase out nuclear power and extended the life of a lot of old reactors. Now Chancellor Merkel has had to partially abandon her policy, declaring a three-month moratorium on the extension… Sounds complicated? (More background on the dw website)There’s a huge debate going on here on whether Germany should go it alone on abandoning nuclear. It reminds me of a conversation I had with Professor Carlos Duarte, a leading scientist involved in he EU\’s “Arctic Tipping Points” programme. (Listen to the story on how the Arctic is setting off alarm bells for the global climate on Living Planet.) When it comes to halting climate change, he told me the time for governments to wait and see who will make the first move is over, somebody needs to go ahead unilaterally and take the first steps. I\’d say the same applies to nuclear power. I wonder how some of the key figures who shifted from an anti- to a pro-nuclear stance because of the urgency of climate change are feeling now?
I hope this latest catastrophe will push support for renewables. But of course there is the danger that countries opting out of nuclear will burn more fossil fuels. We seem to be caught in a very vicious circle…
DateMarch 18, 2011 | 11:41 am
On the trail of the truth about Greenland
Running for campus…
Let me recommend you a website and the book it’s based on.I’ve seen it here and it’s very impressive:Arctic Tipping Points
is the title, and it contains some beautiful and in some cases moving images relating to climate change and the Arctic. The editors are Carlos Duarte (quoted in earlier post) and Paul Wassmann (University of Tromsö.
(No tipping point for these swings)
I have been following the presentations dealing with the Greenland ice sheet closely. Sometimes it is a little frustrating when speakers hint at important results of studies which they cannot reveal fully ahead of publication. If you guys are trying to increase the suspense and arouse my interest in reports coming out in the next few months – you have succeeded. On the other hand, it seems a pity, with quite a few journalists sitting in the conference, that we can’t use the opportunity to pass on some interesting results. Unfortunate timing, it seems some of the reports were originally planned to have been ready. But let me sum up what I can here.
Peter Wadhams, Professor of Ocean Physics at the University of Cambridge introduced the strain of the conference dedicated to “ice-ocean-atmosphere interactions in the Arctic”. He refered to very large changes on the Greenland ice sheet, with very large areas of melt occurring in summer and a substantial net flux of fresh water into the sea every year. Now that is one of the key factors in measuring the changes. He told us the amount was almost the same as the total melt from mountain glaciers, suggesting this could be making a comparable contribution to global sea level rise as melt from all the rest of the glaciers in the world put together. He stressed the rate of melt on Greenland is accelerating and scientists just don’t know how the acceleration rate will continue.
Lars Otto Reiersen is the Executive Secretary for AMAP, the Arctic Monitoring and Assessment Programme. He reported on the SWiPA (Project) (Snow, Water, Ice and Permafrost in the Arctic), which is preparing a report to be presented to a meeting of Arctic ministers in May. (sigh!) Suffice it to say, he indicated that when it comes to the mass balance of the Greenland ice sheet, the updated figures will show even higher melt. All will be revealed in a few months, it seems. And it will not be cheery reading.
Late afternoon impression of Tromsö campus while the weather was still beautiful (some like it cold). It is thawing at the moment, but forecast to cool again soon.
DateJanuary 27, 2011 | 3:55 pm