Once again, it looks like claims of ‘consensus’ are overblown. In our previous news item we have this:
…ice sheets are the largest potential source of future sea level rise – and they also possess the largest uncertainty over their future behaviour.
and
Yet, there is no consensus among scientists about the cause of this recent increase in ice sheet mass loss observed by satellites. Beside anthropogenic warming, ice sheets are affected by many natural processes…
Yet these folks at the Potsdam Institute for Climate Impact Research are certain they have the numbers dialed in. No matter who you believe, clearly there’s no consensus. Which one do you think will get the headlines? I’m betting Potsdam due to the “if it bleeds it leads” nature of their press release.
Each degree of global warming might ultimately raise global sea levels by more than 2 meters
07/15/2013 – Greenhouse gases emitted today will cause sea level to rise for centuries to come. Each degree of global warming is likely to raise sea level by more than 2 meters in the future, a study now published in the Proceedings of the National Academy of Sciences shows. While thermal expansion of the ocean and melting mountain glaciers are the most important factors causing sea-level change today, the Greenland and Antarctic ice sheets will be the dominant contributors within the next two millennia, according to the findings. Half of that rise might come from ice-loss in Antarctica which is currently contributing less than 10 percent to global sea-level rise.
“CO2, once emitted by burning fossil fuels, stays an awful long time in the atmosphere,” says Anders Levermann, lead author of the study and research domain co-chair at the Potsdam Institute for Climate Impact Research. “Consequently, the warming it causes also persists.” The oceans and ice sheets are slow in responding, simply because of their enormous mass, which is why observed sea-level rise is now measured in millimeters per year. “The problem is: once heated out of balance, they simply don’t stop,” says Levermann. “We’re confident that our estimate is robust because of the combination of physics and data that we use.”
The study is the first to combine evidence from early Earth’s climate history with comprehensive computer simulations using physical models of all four major contributors to long-term global sea-level rise. During the 20th century, sea level rose by about 0.2 meters, and it is projected to rise by significantly less than two meters by 2100 even for the strongest scenarios considered. At the same time, past climate records, which average sea-level and temperature changes over a long time, suggest much higher sea levels during periods of Earth history that were warmer than present.
For the study now published, the international team of scientists used data from sediments from the bottom of the sea and ancient raised shorelines found on various coastlines around the world. All the models are based on fundamental physical laws. “The Antarctic computer simulations were able to simulate the past five million years of ice history, and the other two ice models were directly calibrated against observational data – which in combination makes the scientists confident that these models are correctly estimating the future evolution of long-term sea-level rise,” says Peter Clark, a paleo-climatologist at Oregon State University and co-author on the study. While it remains a challenge to simulate rapid ice-loss from Greenland and Antarctica, the models are able to capture ice loss that occurs on long time scales where a lot of the small rapid motion averages out.
If global mean temperature rises by 4 degrees compared to pre-industrial times, which in a business-as-usual scenario is projected to happen within less than a century, the Antarctic ice sheet will contribute about 50 percent of sea-level rise over the next two millennia. Greenland will add another 25 percent to the total sea-level rise, while the thermal expansion of the oceans’ water, currently the largest component of sea-level rise, will contribute about 20 percent, and the contribution from mountain glaciers will decline to less than 5 percent, mostly because many of them will shrink to a minimum.
“Continuous sea-level rise is something we cannot avoid unless global temperatures go down again,” concludes Levermann. “Thus we can be absolutely certain that we need to adapt. Sea-level rise might be slow on time scales on which we elect governments, but it is inevitable and therefore highly relevant for almost everything we build along our coastlines, for many generations to come.”
Article: Levermann, A., Clark, P., Marzeion, B., Milne, G., Pollard, D., Radic, V., Robinson, A. (2013): The multimillennial sea-level commitment of global warming. Proceedings of the National Academy of Sciences (early online edition) [DOI: 10.1073/pnas.1219414110 ]
Weblink to the article once it is published: www.pnas.org/cgi/doi/10.1073/pnas.1219414110
Weblink to the article in open access once it is published: http://www.pnas.org/content/early/recent
Source or press release: http://www.pik-potsdam.de/news/press-releases/jedes-grad-erderwaermung-koennte-den-meeresspiegel-auf-lange-sicht-um-mehr-als-2-meter-erhoehen
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Oh. Well in that case. Since you’ve used a combination of physics and data, I guess that settles it.
I mean, really? What the heck sort of statement is that? Usually when people talk about confidence and robustness there is some mention of uncertainties and confidence intervals instead of a flat assertation that the result is robust because ‘we used a combination of physics and data’…
“We’re confident that our estimate is robust because of the combination of physics and data that we use.”
It makes a pleasant change for the alarmists to actually use any physics or real empirical data, at all, so using both is a vast improvement….
Although that does not mean that they used them properly.
OT but I think Google has found a way to post skeptic stories but about a month late. On the other hand, AGW stories are published immediately. If you type “global warming scam” ect, in Google News, most of the stories are weeks or months old. If you type “global warming” all the recent alarmist stories are there.
“CO2, once emitted by burning fossil fuels, stays an awful long time in the atmosphere,”
Go back, start over.
You should realise that the patients at the Potsdam Institute for Climate Impact Research Asylum have taken over their daily climastrology rantings.
Statement, corrected:
“We’re confident that our estimate is robust because we have changed the definition of “robust” to mean anything we want it to mean at any particular moment.”
“Half of that rise might come from ice-loss in Antarctica which is currently contributing less than 10 percent to global sea-level rise.”
I thought the ice extent for Antarctica is near its record for the satellite era. Where did the nearly 10 percent come from? The extent is near record but the volume is substantially reduced?
To be clear – one side says there is no consensus, and the other side says there is a consensus.
Is there a meta-consensus on whether or not the consensus side is correct, or is it the non-consensus side that has the consensus?
Weasel words again – “less than 10 percent” obviously includes -ve contributions to sea level rise, so is technically true, but …..
Beautifull! Now we know that things will get worse, unless they get better.
Ultmate rise prediction is 2 meters/degree rise and ultimate is 2,000 years? Do these guys ever have it dialed in. So, we’d get 8 meters for the 4°C by 4013. I wonder if that comes with a money back guarantee?
More dueling…………at Reuters. The consensus is crumbling before our very eyes. 2013, after Climategate, is their second Annus horribilis.
“The oceans and ice sheets are slow in responding, simply because of their enormous mass,…”
If there is such inertia how come the poles lose between 60% and 70% every year?
Let’s see, over the last hundred years, we’ve had a temperature increase of about 1 deg. C and sea level has risen … 7 inches. I wonder how their model explains that?
@ur momisugly dave, July 16, 2013 at 10:11 am
You are confusing sea ice (typically a few meters thick floating in the oceans) with ice sheets (typically a few km thick resting on land). Floating sea ice will have minimal impacts on sea level. Land-based ice sheets can have a large impact if the H2O flows off into the ocean.
“Consequently, the warming it causes also persists.”
…he said 17 years ago
The study is the first to combine evidence from early Earth’s climate history with comprehensive computer simulations using physical models of all four major contributors to long-term global sea-level rise. During the 20th century, sea level rose by about 0.2 meters, and it is projected to rise by significantly less than two meters by 2100 even for the strongest scenarios considered. At the same time, past climate records, which average sea-level and temperature changes over a long time, suggest much higher sea levels during periods of Earth history that were warmer than present.
An interesting historical fact. Amsterdam – which is not known for its towering height above sea level – was founded as a fishing village at the edge of the sea at the height of the Medieval Warm Period when Vikings were farming areas of Greenland that is currently permafrost. Temperatures were obviously significantly higher in Greenland for a few <centuries yet Amsterdam has remained on the edge of the sea at sea level since its founding in the late 12th century. History shows that at no time did the sea leave Amsterdam high and dry, and now when it is warm again Amsterdam is still in existence on the coast as a major port.
Perhaps the “comprehensive computer simulations” need different tuning parameters?
Okay, just a few things:
“The problem is: once heated out of balance, they simply don’t stop,” says Levermann.
Heated out of balance?!
“The study is the first to combine evidence from early Earth’s climate history with comprehensive computer simulations using physical models of all four major contributors to long-term global sea-level rise.”
Let’s see, I guess that’s CO2, CO2, CO2 & CO2?
“…and the other two ice models were directly calibrated against observational data – which in combination makes the scientists confident that these models are correctly estimating the future evolution of long-term sea-level rise…”
Directly calibrated against observational data? Do they mean all 11 years worth of satellite data from GRACE?
How terribly impressive.
Levermann paper is here.
http://www.pik-potsdam.de/~anders/publications/levermann_clark13.pdf
Hansen predicted over 20 years ago that parts of New York City would be under water now. He had that dialed in too!
“CO2, once emitted by burning fossil fuels, stays an awful long time in the atmosphere,”
Wow. Does the author mean the ~3% of the total CO2 emitted into the atmosphere each year? And—exactly what are the physical properties that make CO2 from fossil fuels differ from CO2 from natural sources?
The world—and science—want to know.
Ian W says:
July 16, 2013 at 10:59 am
.. yet Amsterdam has remained on the edge of the sea at sea level since its founding …
… History shows that at no time did the sea leave Amsterdam high and dry, …
========================================================
Amsterdam has been connected to the North Sea by the Noordzeekanaal since the mid 19th century. It’s about 25km long.
“Thus we can be absolutely certain that we need to adapt. Sea-level rise might be slow on time scales on which we elect governments, but it is inevitable and therefore highly relevant for almost everything we build along our coastlines, for many generations to come.”
Of course they do not know that sea-level rise is inevitable. But whether it rises, falls, or stays the same makes little difference to the developments now along coastlines. A nice firm surge from a moderately intense storm during a high tide ought to be of immediate concern. About 40% (?) of the area of Detroit is open for resettlement. A few hundred thousand folks could move off the sand and sediment, re-populate Detroit, and solve two major issues faced by the USA. Not building new housing and related structures along coastlines does have a nice common sense sound to it.
View from the Solent says:
July 16, 2013 at 11:33 am
Ian W says:
July 16, 2013 at 10:59 am
.. yet Amsterdam has remained on the edge of the sea at sea level since its founding …
… History shows that at no time did the sea leave Amsterdam high and dry, …
========================================================
Amsterdam has been connected to the North Sea by the Noordzeekanaal since the mid 19th century. It’s about 25km long.
And how many rising locks are there on the Noordzeekanaal?
Eliza says:
July 16, 2013 at 9:46 am
“OT but I think Google has found a way to post skeptic stories but about a month late. On the other hand, AGW stories are published immediately. If you type “global warming scam” ect, in Google News, most of the stories are weeks or months old. If you type “global warming” all the recent alarmist stories are there.”
No. Global Warming Scam is simply a longer phrase and therefore less likely to be used at any given time. Google attempts to give precise matches first, and as usage of the phrase is much rarer than Global Warming alone you get matches that are on average older. Larry & Sergej and Eric may be cynical liberal top dogs but nobody including the NSA gives a fart for the phrase “Global Warming Scam”.