UN climate science body IPCC condemns AR5 report leak
http://www.rtcc.org/un-climate-science-body-ipcc-condemns-ar5-report-leak/
http://www.rtcc.org/un-climate-science-body-ipcc-condemns-ar5-report-leak/
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http://www.nytimes.com/2013/07/23/u...swers-in-glaciers-summer-flood-surges.html?hp
Alaska Looks for Answers in Glacier’s Summer Flood Surges
By KIRK JOHNSON
JUNEAU, Alaska — The idea that glaciers change at a glacial speed is increasingly false. They are melting and retreating rapidly all over the world. But the unpredictable flood surges at the Mendenhall Glacier, about 14 miles from downtown Juneau, Alaska’s capital, are turning a jog into a sprint as global temperatures and climate variability increase.
Starting in July 2011, and each year since, sudden torrents of water shooting out from beneath the glacier have become a new facet of Juneau’s brief, shimmering high summer season. In that first, and so far biggest, measured flood burst, an estimated 10 billion gallons gushed out in three days, threating homes and property along the Mendenhall River that winds through part of the city. There have been at least two smaller bursts this year.
“That first one caught us by surprise,” said Tom Mattice, the emergency programs manager and avalanche forecaster for the City and Borough of Juneau.
That the Mendenhall Glacier is thinning, and has been for decades, is only part of the explanation. Water from snowmelt, rain and thawing ice are also combining in new ways, researchers said — first pooling in an ice-covered depression near the glacier called Suicide Basin, then finding a way to flow downhill.
What prompts a surge, and the urgent search for a way to anticipate and prepare by scientists and safety officials like Mr. Mattice, is pressure. As water builds up in the basin and seeks an outlet, it can actually lift portions of the glacier ever so slightly, and in that lift, the water finds a release. Under the vast pressure of the ice bearing down upon it, the water explodes out into the depths of Mendenhall Lake and from there into the river.
Glaciologists even have a name for the process, which is happening in many places all over the world as climates change: jokulhlaup, an Icelandic word usually translated as “glacier leap.”
“We don’t have a sense yet how much of a threat this poses, or how much water you could store up there,” said Jason Amundson, an assistant professor of geophysics at the University of Alaska Southeast, in Juneau.
What elevates the concern is the proximity of people, and lots of them. Glaciers may be leaping in many places, but it mostly happens in isolation.
The roughly 12-mile-long Mendenhall, by contrast, is one of the most visited glaciers in the world, and an urban one. About 400,000 tourists a year, 80 percent of them from the cruise ships that stop at the Port of Juneau, are drawn to the glacier.
“We’re a drive-up glacier,” said Nikki Hinds, the assistant director at the Mendenhall Glacier Visitor Center, which is operated by the Forest Service. “In how many places can you have that?”
This summer, glacier-monitoring intensified. A pressure transducer to gauge water buildup, partly paid for by the city, was installed in a deep crack on the edge of the basin, with a satellite link sending back real-time data about the glacier’s hidden waterworks. A time-lapse camera was also positioned at the main pooling site for the first time to track bulges in the ice that could suggest dammed-up water.
“The biggest thing we don’t know is what’s blocking what,” said Jamie Pierce, a mountaineer and researcher at the university. Mr. Pierce was out on the Mendenhall ice on a recent afternoon, checking the instruments. After rappelling about 50 feet to the transducer, he found it completely dry, suggesting that the water was finding another channel, or another damming point, than the one suspected of causing the trouble.
Like glaciers the world over, the Mendenhall has thinned and retreated hundreds of feet since visitors first started coming here in the late 1800s. Long-term climate models suggest a warmer, wetter pattern in this part of Alaska, which could have its own strange ripple of consequences for the Mendenhall and the people who love it, study it and live by it.
Warmer temperatures could mean more rain and less snow at lower elevations, said Tom Ainsworth, the meteorologist in charge at the National Weather Service office in Juneau. That could intensify runoff and the frequency of surges. But more precipitation, he said, could also bring more snow to higher elevations. Greater annual snowfall, repeated over many years, could cause some glaciers, or portions of glaciers, to grow as snow compacts into the ice.
That paradoxical picture — glaciers shrinking, glaciers growing, more rain, more snow, more heat — can be difficult to communicate or grasp in the brief time that most tourists spent at the glacier.
“You’re on a time schedule,” said Sherry Reese, 65, a retired corporate travel manager from Denton, Tex., who was walking on a trail near the visitor center on a one-hour tour last week with her husband, Alan. “That’s it. You saw it. Next!”
Mr. Reese said the net result is that most people are probably not able to even imagine the glacier changing at all, so big and eternal it can seem in its blue-tinged majesty.
“They see what they see and that’s what it is, not recognizing what it was 500 years ago,” said Mr. Reese, who, like his wife, was wearing a sweatshirt against the chill of the ice, with “Alaska” printed across the front.
Alaska Looks for Answers in Glacier’s Summer Flood Surges
By KIRK JOHNSON
JUNEAU, Alaska — The idea that glaciers change at a glacial speed is increasingly false. They are melting and retreating rapidly all over the world. But the unpredictable flood surges at the Mendenhall Glacier, about 14 miles from downtown Juneau, Alaska’s capital, are turning a jog into a sprint as global temperatures and climate variability increase.
Starting in July 2011, and each year since, sudden torrents of water shooting out from beneath the glacier have become a new facet of Juneau’s brief, shimmering high summer season. In that first, and so far biggest, measured flood burst, an estimated 10 billion gallons gushed out in three days, threating homes and property along the Mendenhall River that winds through part of the city. There have been at least two smaller bursts this year.
“That first one caught us by surprise,” said Tom Mattice, the emergency programs manager and avalanche forecaster for the City and Borough of Juneau.
That the Mendenhall Glacier is thinning, and has been for decades, is only part of the explanation. Water from snowmelt, rain and thawing ice are also combining in new ways, researchers said — first pooling in an ice-covered depression near the glacier called Suicide Basin, then finding a way to flow downhill.
What prompts a surge, and the urgent search for a way to anticipate and prepare by scientists and safety officials like Mr. Mattice, is pressure. As water builds up in the basin and seeks an outlet, it can actually lift portions of the glacier ever so slightly, and in that lift, the water finds a release. Under the vast pressure of the ice bearing down upon it, the water explodes out into the depths of Mendenhall Lake and from there into the river.
Glaciologists even have a name for the process, which is happening in many places all over the world as climates change: jokulhlaup, an Icelandic word usually translated as “glacier leap.”
“We don’t have a sense yet how much of a threat this poses, or how much water you could store up there,” said Jason Amundson, an assistant professor of geophysics at the University of Alaska Southeast, in Juneau.
What elevates the concern is the proximity of people, and lots of them. Glaciers may be leaping in many places, but it mostly happens in isolation.
The roughly 12-mile-long Mendenhall, by contrast, is one of the most visited glaciers in the world, and an urban one. About 400,000 tourists a year, 80 percent of them from the cruise ships that stop at the Port of Juneau, are drawn to the glacier.
“We’re a drive-up glacier,” said Nikki Hinds, the assistant director at the Mendenhall Glacier Visitor Center, which is operated by the Forest Service. “In how many places can you have that?”
This summer, glacier-monitoring intensified. A pressure transducer to gauge water buildup, partly paid for by the city, was installed in a deep crack on the edge of the basin, with a satellite link sending back real-time data about the glacier’s hidden waterworks. A time-lapse camera was also positioned at the main pooling site for the first time to track bulges in the ice that could suggest dammed-up water.
“The biggest thing we don’t know is what’s blocking what,” said Jamie Pierce, a mountaineer and researcher at the university. Mr. Pierce was out on the Mendenhall ice on a recent afternoon, checking the instruments. After rappelling about 50 feet to the transducer, he found it completely dry, suggesting that the water was finding another channel, or another damming point, than the one suspected of causing the trouble.
Like glaciers the world over, the Mendenhall has thinned and retreated hundreds of feet since visitors first started coming here in the late 1800s. Long-term climate models suggest a warmer, wetter pattern in this part of Alaska, which could have its own strange ripple of consequences for the Mendenhall and the people who love it, study it and live by it.
Warmer temperatures could mean more rain and less snow at lower elevations, said Tom Ainsworth, the meteorologist in charge at the National Weather Service office in Juneau. That could intensify runoff and the frequency of surges. But more precipitation, he said, could also bring more snow to higher elevations. Greater annual snowfall, repeated over many years, could cause some glaciers, or portions of glaciers, to grow as snow compacts into the ice.
That paradoxical picture — glaciers shrinking, glaciers growing, more rain, more snow, more heat — can be difficult to communicate or grasp in the brief time that most tourists spent at the glacier.
“You’re on a time schedule,” said Sherry Reese, 65, a retired corporate travel manager from Denton, Tex., who was walking on a trail near the visitor center on a one-hour tour last week with her husband, Alan. “That’s it. You saw it. Next!”
Mr. Reese said the net result is that most people are probably not able to even imagine the glacier changing at all, so big and eternal it can seem in its blue-tinged majesty.
“They see what they see and that’s what it is, not recognizing what it was 500 years ago,” said Mr. Reese, who, like his wife, was wearing a sweatshirt against the chill of the ice, with “Alaska” printed across the front.
Arctic thawing could cost the world $60tn, scientists say
Methane released by a thinning permafrost may trigger catastrophic climate change and devastate global economy
Arctic thawing could cost the world $60tn, scientists say | Environment | guardian.co.uk
Methane released by a thinning permafrost may trigger catastrophic climate change and devastate global economy
Arctic thawing could cost the world $60tn, scientists say | Environment | guardian.co.uk
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Arctic expert predicts final collapse of sea ice within four years | Environment | guardian.co.uk
As sea ice shrinks to record lows, Prof Peter Wadhams warns a 'global disaster' is now unfolding in northern latitudes
One of the world's leading ice experts has predicted the final collapse of Arctic sea ice in summer months within four years.
In what he calls a "global disaster" now unfolding in northern latitudes as the sea area that freezes and melts each year shrinks to its lowest extent ever recorded, Prof Peter Wadhams of Cambridge University calls for "urgent" consideration of new ideas to reduce global temperatures.
In an email to the Guardian he says: "Climate change is no longer something we can aim to do something about in a few decades' time, and that we must not only urgently reduce CO2 emissions but must urgently examine other ways of slowing global warming, such as the various geoengineering ideas that have been put forward."
These include reflecting the sun's rays back into space, making clouds whiter and seeding the ocean with minerals to absorb more CO2.
Wadhams has spent many years collecting ice thickness data from submarines passing below the arctic ocean. He predicted the imminent break-up of sea ice in summer months in 2007, when the previous lowest extent of 4.17 million square kilometres was set. This year, it has unexpectedly plunged a further 500,000 sq km to less than 3.5m sq km. "I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer.
"At first this didn't [get] noticed; the summer ice limits slowly shrank back, at a rate which suggested that the ice would last another 50 years or so. But in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months.
"This collapse, I predicted would occur in 2015-16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be complete by those dates".
Wadhams says the implications are "terrible". "The positives are increased possibility of Arctic transport, increased access to Arctic offshore oil and gas resources. The main negative is an acceleration of global warming."
"As the sea ice retreats in summer the ocean warms up (to 7C in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age. As the water warms the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming."
Climate science: Vast costs of Arctic change : Nature : Nature Publishing Group
Arctic Ice Cover, Ice Thickness and Tipping Points
An Error Occurred Setting Your User Cookie
The Future of Arctic Sea Ice
Annual Review of Earth and Planetary Sciences
As sea ice shrinks to record lows, Prof Peter Wadhams warns a 'global disaster' is now unfolding in northern latitudes
One of the world's leading ice experts has predicted the final collapse of Arctic sea ice in summer months within four years.
In what he calls a "global disaster" now unfolding in northern latitudes as the sea area that freezes and melts each year shrinks to its lowest extent ever recorded, Prof Peter Wadhams of Cambridge University calls for "urgent" consideration of new ideas to reduce global temperatures.
In an email to the Guardian he says: "Climate change is no longer something we can aim to do something about in a few decades' time, and that we must not only urgently reduce CO2 emissions but must urgently examine other ways of slowing global warming, such as the various geoengineering ideas that have been put forward."
These include reflecting the sun's rays back into space, making clouds whiter and seeding the ocean with minerals to absorb more CO2.
Wadhams has spent many years collecting ice thickness data from submarines passing below the arctic ocean. He predicted the imminent break-up of sea ice in summer months in 2007, when the previous lowest extent of 4.17 million square kilometres was set. This year, it has unexpectedly plunged a further 500,000 sq km to less than 3.5m sq km. "I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer.
"At first this didn't [get] noticed; the summer ice limits slowly shrank back, at a rate which suggested that the ice would last another 50 years or so. But in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months.
"This collapse, I predicted would occur in 2015-16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be complete by those dates".
Wadhams says the implications are "terrible". "The positives are increased possibility of Arctic transport, increased access to Arctic offshore oil and gas resources. The main negative is an acceleration of global warming."
"As the sea ice retreats in summer the ocean warms up (to 7C in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age. As the water warms the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming."
Climate science: Vast costs of Arctic change : Nature : Nature Publishing Group
Arctic Ice Cover, Ice Thickness and Tipping Points
An Error Occurred Setting Your User Cookie
The Future of Arctic Sea Ice
Annual Review of Earth and Planetary Sciences
What’s behind the battle of received wisdoms?
http://blogs.nottingham.ac.uk/makin.../whats-behind-the-battle-of-received-wisdoms/
This is a guest essay by Ben Pile, a writer for Spiked Online and his own blog Climate Resistance.
http://blogs.nottingham.ac.uk/makin.../whats-behind-the-battle-of-received-wisdoms/
This is a guest essay by Ben Pile, a writer for Spiked Online and his own blog Climate Resistance.
Too late now for 2013 to produce Greenland ice surface melting anywhere near as large as in 2012
Meltfactor
Meltfactor
Greenland's Melting Ice Sheets: Climate Change's Disastrous Effects
http://www.rollingstone.com/greenland-melting
http://www.rollingstone.com/greenland-melting
Is Reuters inserting editorial comment into its coverage of climate change?
Is Reuters inserting editorial comment into its coverage of climate change? | Knight Science Journalism Program at MIT
Is Reuters inserting editorial comment into its coverage of climate change? | Knight Science Journalism Program at MIT
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Leaving Our Descendants A Whopping Rise In Sea Levels By Fen Montaigne
Leaving Our Descendants A Whopping Rise in Sea Levels by Fen Montaigne: Yale Environment 360
Leaving Our Descendants A Whopping Rise In Sea Levels
By Fen Montaigne
26 July, 2013
Yale Environment 360
German scientist Anders Levermann and his colleagues have released research that warns of major sea level increases far into the future. In an interview with Yale Environment 360, he raises important questions about how much we really care about the world we will leave to those who come after us.
Last week, a group of scientists led by Anders Levermann of the Potsdam Institute for Climate Change Research released a paper that made a stark forecast: For every 1 degree Celsius of temperature increase, the world will eventually experience a 2.3-meter increase in sea level. That means that should carbon emissions continue to rise at or near current rates, and temperatures soar 4 to 5 degrees C in the next century or two, the world could well experience sea level increases of many meters — dozens of feet — in the centuries and millennia to come.
Levermann is a scientist, not an ethicist — he is lead author of the sea level chapter in the upcoming fifth report of the Intergovernmental Panel on Climate Change — but he is acutely aware of the import of his research for future generations. In an interview with Yale Environment 360 senior editor Fen Montaigne, Levermann discusses how he and his colleagues reached their conclusions, how much disruption such large sea level increases might cause, and why we need to ponder the effect of our actions on future generations. “Society needs to decide about how much damage it wants to do in the future and how much damage future generations can actually cope with,” he says.
Yale Environment 360: What are the main points that you think readers should take away from this paper?
Anders Levermann: The real new thing is we have asked the question not how much sea level rise will there be in 2100, but rather how much sea level rise are we already committed to at a certain level of global warming? And these numbers are much higher than the numbers we expect in 2100.
Sea level is like a big ball — it takes a while until you get it rolling, but once it’s rolling you can’t stop it easily. The projections by 2100 are significantly below 2 meters [6.6 feet] of global sea level rise. But we expect over a period of 2,000 years a sea level rise of 2 meters for each degree Celsius of warming. Now if you look at the projections for temperature by 2100, a business-as-usual scenario in which we increase the CO2 emissions every year like we have done in the past would lead to a warming of about 4 to 5 degrees Celsius [7 to 9 degrees F]. And long-term, 4 to 5 degrees in our study translates to something in the vicinity of 9 meters [29.6 feet] of sea level rise. So it’s less than 2 meters sea level rise projected for 2100, but in the long term it’s 9 meters.
e360: So you’re saying once this warming is in the atmosphere, it’s going to take a while for the melting of various ice sheets and the thermal expansion of water to catch up to it?
Levermann: What I’m saying is once you put a certain amount of CO2 in the atmosphere, you’ll have to live with the corresponding warming for a long time. This is a problem we look into with respect to sea level rise because this long-term warming results in a long-term sea level rise that will not stop in 2100, but will go on and on for a long time.
e360: Could you discuss your confidence in your findings and what measurements and models you used to make sure that the numbers you came up with represent a pretty reasonable forecast.
Levermann: What we have done is we take the state of the art physical models for each component that is relevant for sea level rise — the thermal expansion of the ocean, melting of [mountain] glaciers, and melting of the Greenland and Antarctic ice sheets — we take these four models and ask the question: How much sea level rise do you get after 2,000 years when you elevate the temperature? Then we add them all together and we get a result for the total sea level contribution for different levels of warming and then we compare this to the paleological data. All of this gives a consistent picture, which says we can expect an increase in sea level of 2.3 meters for each degree of warming.
e360: Tell me a little bit about the paleo data?
Levermann: When you go into paleo records you can never use direct measurements because there was obviously no one around taking measurements 10,000 years ago or even longer. So that’s why you use what we call proxy data, where we use certain chemical components or isotopes in order to make statements about, first, the temperature, and then the sea level. Sea level has an additional way we can derive it from, and that’s simply from looking at the sea level that you see in the geological record. In some places around the world, you can simply see where the sea level was at certain times in history.
e360: Let’s say we continue on the current path of emissions and that by 2100 we are 4-5 degrees Centigrade hotter than we are now. How long after that do you think you could begin to see significant sea level rise as the Antarctic and Greenland ice sheets begin to melt at a more rapid rate?
Levermann: Significant is very much defined here by society. The 20 centimeters [8 inches] that we have observed in the last 100 years are significant for the smaller island states in the Pacific, which are inevitably going to vanish in the future. And also, for example, tropical storm Nargis in Myanmar in 2008 went much farther inland because of this additional 20 centimeters than it would have in pre-industrial times.
So the question of what is significant is very much dependent on the coastline you look at and what society wants or can adapt to. I would say that a meter in the 21st century would be highly significant for the Netherlands and Europe, but also for London and Florida and New York and so on because you always have to add on top the storm surges.
We picked the 2,000 years date because it is far enough in the future so that the small scale variations and the sea level rise have been averaged out. So we can be quite certain that after 2,000 years this kind of sea level rise will be observed, but it could be well before that.
e360: If the conclusions of your research are correct, civilization is going to be looking at sea level rise that could well exceed 5 meters [16 feet], or could be 10 meters within the next 2,000 years. These are really massive increases. What do you think your paper says about adaptation and what the world needs to be doing now about adaptation?
Levermann: What I would say in short is that we simply put expiration dates on certain cultures, on certain societies around the globe. Definitely for some small island states in the Pacific and in the tropics in general, but also for regions that are now low-lying, like the Netherlands and Bangladesh, and also regions in the U.S. And that simply poses the question of what kind of infrastructure we build, what buildings we build — the churches, the power plants, and so on. For what time period do we build them and is there a cultural heritage we have to abandon in the long run?
e360: Your term “expiration date” is striking. With 5 or 10 meters of sea level rise, you would be looking at an expiration date, if you would, for much of the world’s coastal areas, would you not?
Levermann: I think it’s culturally very important whether we have an open-ended future or whether we can say there’s a limit to it. If you are living on a Pacific island, and you simply know that in 100 years your home won’t be there anymore, then I would assume you build your society differently, you think differently about your children, about your grandchildren. And with these kinds of numbers we’ll have to do something similar. People will have to reconsider what’s home and how long you build a home for.
e360: How would you characterize society’s understanding and acceptance of these facts at this point?
Levermann: There’s one very important aspect to the adaptation problem and that is that people consider this to be a local problem and I would strongly argue against it. We are living a globalized world and our societies are relatively fragile already. Now after Fukushima — the Japanese catastrophe — we had supply failures in Europe in the automobile industry.The same was true after the great recent Thailand flood — we had a shortage of hard drives in the U.S. and in Europe for months in 2012 and this was really not expected. So we had a remote event which impacted us from afar. Now if we don’t get hard drives for a while that won’t collapse a society obviously. But what happens if we get a whole series of these kinds of impacts like Katrina and Sandy in the same year, and a drought and a heat wave that brings the California electricity sector into collapse or something. Will this stay within the U.S. or will it spread around the world? And this is why we need to consider adaptation as a global problem.
A lot of transportation routes at the moment depend on harbors or infrastructure that is close to the coastline. If, for example, a storm surge would destroy the harbor of Rotterdam, where a lot of containers go through, you would strongly disrupt the supply chains for a lot of production in different countries. This is why sea level rise and the associated storm surges directly lead into a global adaptation problem because what we have to do is we have to rearrange our supply network in a way that is robust against terror attacks of nature, if you like. That’s in a sense what it is — it’s not intentional, obviously that’s why it is not a terror attack, but it’s a localized disruption by nature on our supply chain, which requires a robust supply network. I believe that this global supply network would adapt by itself, if it was given the information about its vulnerability. We are planning to set-up a Web-platform similar to Wikipedia where such information is gathered and provided. It will be launched at Zeean.
e360: When we are talking about 500 years, 1,000 years, 2,000 years, that’s really distant in time. In 100 years one can imagine one’s grandchildren for example, but in 2,000 years of course that’s unimaginable. How do you get society to care about potential long-term impacts when they and their grandchildren will be long gone?
Levermann: This is a really difficult problem. It’s not for climate scientists to decide — that should be decided by society. So society needs to decide about its time horizons with respect to its cultural heritage and how much damage it wants to do in the future and how much damage future generations can actually cope with. I haven’t decided for myself what is really worthwhile saving and what is the price we are willing to pay for saving, for example, the coastline of Florida. But this cannot be solved by natural science obviously, so what we do is we put out the information about what is going to happen and then society needs to decide what to do. Do we want to keep the Tower of London, or do we just say this was nice for a few centuries but now it will be flooded in the next few hundred years.
I personally believe that we cannot adapt to a warming of 4 or 5 degrees [C] because the increase in extreme events and also sea level rise, combined with extreme storm surges, will simply increase the pressure on our complex societies, which might bring them to the verge of collapse. Obviously, we do not know whether this will happen, but I think that such a threshold is out there somewhere — we just do not know where. We do need to adapt to the climate change that cannot be avoided anymore, but we definitely need to mitigate any warming that we cannot adapt to.
© 2008-2013 Yale University
Leaving Our Descendants A Whopping Rise in Sea Levels by Fen Montaigne: Yale Environment 360
Leaving Our Descendants A Whopping Rise In Sea Levels
By Fen Montaigne
26 July, 2013
Yale Environment 360
German scientist Anders Levermann and his colleagues have released research that warns of major sea level increases far into the future. In an interview with Yale Environment 360, he raises important questions about how much we really care about the world we will leave to those who come after us.
Last week, a group of scientists led by Anders Levermann of the Potsdam Institute for Climate Change Research released a paper that made a stark forecast: For every 1 degree Celsius of temperature increase, the world will eventually experience a 2.3-meter increase in sea level. That means that should carbon emissions continue to rise at or near current rates, and temperatures soar 4 to 5 degrees C in the next century or two, the world could well experience sea level increases of many meters — dozens of feet — in the centuries and millennia to come.
Levermann is a scientist, not an ethicist — he is lead author of the sea level chapter in the upcoming fifth report of the Intergovernmental Panel on Climate Change — but he is acutely aware of the import of his research for future generations. In an interview with Yale Environment 360 senior editor Fen Montaigne, Levermann discusses how he and his colleagues reached their conclusions, how much disruption such large sea level increases might cause, and why we need to ponder the effect of our actions on future generations. “Society needs to decide about how much damage it wants to do in the future and how much damage future generations can actually cope with,” he says.
Yale Environment 360: What are the main points that you think readers should take away from this paper?
Anders Levermann: The real new thing is we have asked the question not how much sea level rise will there be in 2100, but rather how much sea level rise are we already committed to at a certain level of global warming? And these numbers are much higher than the numbers we expect in 2100.
Sea level is like a big ball — it takes a while until you get it rolling, but once it’s rolling you can’t stop it easily. The projections by 2100 are significantly below 2 meters [6.6 feet] of global sea level rise. But we expect over a period of 2,000 years a sea level rise of 2 meters for each degree Celsius of warming. Now if you look at the projections for temperature by 2100, a business-as-usual scenario in which we increase the CO2 emissions every year like we have done in the past would lead to a warming of about 4 to 5 degrees Celsius [7 to 9 degrees F]. And long-term, 4 to 5 degrees in our study translates to something in the vicinity of 9 meters [29.6 feet] of sea level rise. So it’s less than 2 meters sea level rise projected for 2100, but in the long term it’s 9 meters.
e360: So you’re saying once this warming is in the atmosphere, it’s going to take a while for the melting of various ice sheets and the thermal expansion of water to catch up to it?
Levermann: What I’m saying is once you put a certain amount of CO2 in the atmosphere, you’ll have to live with the corresponding warming for a long time. This is a problem we look into with respect to sea level rise because this long-term warming results in a long-term sea level rise that will not stop in 2100, but will go on and on for a long time.
e360: Could you discuss your confidence in your findings and what measurements and models you used to make sure that the numbers you came up with represent a pretty reasonable forecast.
Levermann: What we have done is we take the state of the art physical models for each component that is relevant for sea level rise — the thermal expansion of the ocean, melting of [mountain] glaciers, and melting of the Greenland and Antarctic ice sheets — we take these four models and ask the question: How much sea level rise do you get after 2,000 years when you elevate the temperature? Then we add them all together and we get a result for the total sea level contribution for different levels of warming and then we compare this to the paleological data. All of this gives a consistent picture, which says we can expect an increase in sea level of 2.3 meters for each degree of warming.
e360: Tell me a little bit about the paleo data?
Levermann: When you go into paleo records you can never use direct measurements because there was obviously no one around taking measurements 10,000 years ago or even longer. So that’s why you use what we call proxy data, where we use certain chemical components or isotopes in order to make statements about, first, the temperature, and then the sea level. Sea level has an additional way we can derive it from, and that’s simply from looking at the sea level that you see in the geological record. In some places around the world, you can simply see where the sea level was at certain times in history.
e360: Let’s say we continue on the current path of emissions and that by 2100 we are 4-5 degrees Centigrade hotter than we are now. How long after that do you think you could begin to see significant sea level rise as the Antarctic and Greenland ice sheets begin to melt at a more rapid rate?
Levermann: Significant is very much defined here by society. The 20 centimeters [8 inches] that we have observed in the last 100 years are significant for the smaller island states in the Pacific, which are inevitably going to vanish in the future. And also, for example, tropical storm Nargis in Myanmar in 2008 went much farther inland because of this additional 20 centimeters than it would have in pre-industrial times.
So the question of what is significant is very much dependent on the coastline you look at and what society wants or can adapt to. I would say that a meter in the 21st century would be highly significant for the Netherlands and Europe, but also for London and Florida and New York and so on because you always have to add on top the storm surges.
We picked the 2,000 years date because it is far enough in the future so that the small scale variations and the sea level rise have been averaged out. So we can be quite certain that after 2,000 years this kind of sea level rise will be observed, but it could be well before that.
e360: If the conclusions of your research are correct, civilization is going to be looking at sea level rise that could well exceed 5 meters [16 feet], or could be 10 meters within the next 2,000 years. These are really massive increases. What do you think your paper says about adaptation and what the world needs to be doing now about adaptation?
Levermann: What I would say in short is that we simply put expiration dates on certain cultures, on certain societies around the globe. Definitely for some small island states in the Pacific and in the tropics in general, but also for regions that are now low-lying, like the Netherlands and Bangladesh, and also regions in the U.S. And that simply poses the question of what kind of infrastructure we build, what buildings we build — the churches, the power plants, and so on. For what time period do we build them and is there a cultural heritage we have to abandon in the long run?
e360: Your term “expiration date” is striking. With 5 or 10 meters of sea level rise, you would be looking at an expiration date, if you would, for much of the world’s coastal areas, would you not?
Levermann: I think it’s culturally very important whether we have an open-ended future or whether we can say there’s a limit to it. If you are living on a Pacific island, and you simply know that in 100 years your home won’t be there anymore, then I would assume you build your society differently, you think differently about your children, about your grandchildren. And with these kinds of numbers we’ll have to do something similar. People will have to reconsider what’s home and how long you build a home for.
e360: How would you characterize society’s understanding and acceptance of these facts at this point?
Levermann: There’s one very important aspect to the adaptation problem and that is that people consider this to be a local problem and I would strongly argue against it. We are living a globalized world and our societies are relatively fragile already. Now after Fukushima — the Japanese catastrophe — we had supply failures in Europe in the automobile industry.The same was true after the great recent Thailand flood — we had a shortage of hard drives in the U.S. and in Europe for months in 2012 and this was really not expected. So we had a remote event which impacted us from afar. Now if we don’t get hard drives for a while that won’t collapse a society obviously. But what happens if we get a whole series of these kinds of impacts like Katrina and Sandy in the same year, and a drought and a heat wave that brings the California electricity sector into collapse or something. Will this stay within the U.S. or will it spread around the world? And this is why we need to consider adaptation as a global problem.
A lot of transportation routes at the moment depend on harbors or infrastructure that is close to the coastline. If, for example, a storm surge would destroy the harbor of Rotterdam, where a lot of containers go through, you would strongly disrupt the supply chains for a lot of production in different countries. This is why sea level rise and the associated storm surges directly lead into a global adaptation problem because what we have to do is we have to rearrange our supply network in a way that is robust against terror attacks of nature, if you like. That’s in a sense what it is — it’s not intentional, obviously that’s why it is not a terror attack, but it’s a localized disruption by nature on our supply chain, which requires a robust supply network. I believe that this global supply network would adapt by itself, if it was given the information about its vulnerability. We are planning to set-up a Web-platform similar to Wikipedia where such information is gathered and provided. It will be launched at Zeean.
e360: When we are talking about 500 years, 1,000 years, 2,000 years, that’s really distant in time. In 100 years one can imagine one’s grandchildren for example, but in 2,000 years of course that’s unimaginable. How do you get society to care about potential long-term impacts when they and their grandchildren will be long gone?
Levermann: This is a really difficult problem. It’s not for climate scientists to decide — that should be decided by society. So society needs to decide about its time horizons with respect to its cultural heritage and how much damage it wants to do in the future and how much damage future generations can actually cope with. I haven’t decided for myself what is really worthwhile saving and what is the price we are willing to pay for saving, for example, the coastline of Florida. But this cannot be solved by natural science obviously, so what we do is we put out the information about what is going to happen and then society needs to decide what to do. Do we want to keep the Tower of London, or do we just say this was nice for a few centuries but now it will be flooded in the next few hundred years.
I personally believe that we cannot adapt to a warming of 4 or 5 degrees [C] because the increase in extreme events and also sea level rise, combined with extreme storm surges, will simply increase the pressure on our complex societies, which might bring them to the verge of collapse. Obviously, we do not know whether this will happen, but I think that such a threshold is out there somewhere — we just do not know where. We do need to adapt to the climate change that cannot be avoided anymore, but we definitely need to mitigate any warming that we cannot adapt to.
© 2008-2013 Yale University
Strauss BH. Rapid accumulation of committed sea-level rise from global warming. Proc Natl Acad Sci U S A. http://assets.climatecentral.org/pdfs/Strauss-PNAS-2013.pdf
As carbon emissions and scientific research have accumulated over recent years, climate scientists have come to see global climate change as an increasingly urgent threat.
In PNAS, Levermann et al. provide a powerful new indicator of danger. When their findings on the long-term sensitivity of global sea level to global warming (~2.3 m/°C) are put in the context of recent research on the sensitivity of global temperature to cumulative carbon dioxide emissions, simple analyses suggest that we have already committed to a long-term future sea level >1.3 or 1.9 m higher than today and are adding about 0.32 m/decade to the total: 10 times the rate of observed contemporary sea-level rise.
By midcentury, the central estimate of commitment would rise to >3.1 m assuming today’s trends continue or to 2.1 m under an aggressive emissions cutting and atmospheric carbon dioxide removal scenario. Both scenarios threaten the future viability of many hundreds of coastal municipalities in the United States alone, but the low emissions path would likely spare hundreds more, including many major cities.
Levermann A, et al. (2013) The multimillennial sea-level commitment of global warming. Proc Natl Acad Sci USA. http://www.marzeion.info/sites/default/files/levermann_etal_13.pdf
As carbon emissions and scientific research have accumulated over recent years, climate scientists have come to see global climate change as an increasingly urgent threat.
In PNAS, Levermann et al. provide a powerful new indicator of danger. When their findings on the long-term sensitivity of global sea level to global warming (~2.3 m/°C) are put in the context of recent research on the sensitivity of global temperature to cumulative carbon dioxide emissions, simple analyses suggest that we have already committed to a long-term future sea level >1.3 or 1.9 m higher than today and are adding about 0.32 m/decade to the total: 10 times the rate of observed contemporary sea-level rise.
By midcentury, the central estimate of commitment would rise to >3.1 m assuming today’s trends continue or to 2.1 m under an aggressive emissions cutting and atmospheric carbon dioxide removal scenario. Both scenarios threaten the future viability of many hundreds of coastal municipalities in the United States alone, but the low emissions path would likely spare hundreds more, including many major cities.
Levermann A, et al. (2013) The multimillennial sea-level commitment of global warming. Proc Natl Acad Sci USA. http://www.marzeion.info/sites/default/files/levermann_etal_13.pdf
Climate scientists must not advocate particular policies
Climate scientists must not advocate particular policies | All Models Are Wrong
Climate scientists must not advocate particular policies | All Models Are Wrong
Climate Change and the Open Mind
Barry Bickmore "Climate Change and the Open Mind" on Vimeo
Barry Bickmore "Climate Change and the Open Mind" on Vimeo
2013 shaping up to be one of Australia's hottest years on record
2013 shaping up to be one of Australia's hottest years on record
2013 shaping up to be one of Australia's hottest years on record
A Republican Case for Climate Action
http://www.nytimes.com/2013/08/02/o...e-for-climate-action.html?smid=tw-share&_r=1&
http://www.nytimes.com/2013/08/02/o...e-for-climate-action.html?smid=tw-share&_r=1&
What climate scientists talk about now
What climate scientists talk about now - FT.com
What climate scientists talk about now - FT.com
Hmielowski JD, Feldman L, Myers TA, Leiserowitz A, Maibach E. An attack on science? Media use, trust in scientists, and perceptions of global warming. Public Understanding of Science. An attack on science? Media use, trust in scientists, and perceptions of global warming
There is a growing divide in how conservatives and liberals in the USA understand the issue of global warming. Prior research suggests that the American public’s reliance on partisan media contributes to this gap. However, researchers have yet to identify intervening variables to explain the relationship between media use and public opinion about global warming. Several studies have shown that trust in scientists is an important heuristic many people use when reporting their opinions on science-related topics. Using within-subject panel data from a nationally representative sample of Americans, this study finds that trust in scientists mediates the effect of news media use on perceptions of global warming. Results demonstrate that conservative media use decreases trust in scientists which, in turn, decreases certainty that global warming is happening. By contrast, use of non-conservative media increases trust in scientists, which, in turn, increases certainty that global warming is happening.
There is a growing divide in how conservatives and liberals in the USA understand the issue of global warming. Prior research suggests that the American public’s reliance on partisan media contributes to this gap. However, researchers have yet to identify intervening variables to explain the relationship between media use and public opinion about global warming. Several studies have shown that trust in scientists is an important heuristic many people use when reporting their opinions on science-related topics. Using within-subject panel data from a nationally representative sample of Americans, this study finds that trust in scientists mediates the effect of news media use on perceptions of global warming. Results demonstrate that conservative media use decreases trust in scientists which, in turn, decreases certainty that global warming is happening. By contrast, use of non-conservative media increases trust in scientists, which, in turn, increases certainty that global warming is happening.
BAMS State of the Climate - 2012
BAMS State of the Climate | - 2012
BAMS State of the Climate | - 2012
Seven facts you need to know about the Arctic methane timebomb
Seven facts you need to know about the Arctic methane timebomb | Nafeez Ahmed | Environment | theguardian.com
Seven facts you need to know about the Arctic methane timebomb | Nafeez Ahmed | Environment | theguardian.com
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