Readers may recall the announcement of the PR for the recent paper claiming Sea-Level rise from Antarctic ice sheet could double in WUWT. In a tongue and cheek way, I prefaced it with “Oh Noes!” due to the ridiculous claims being made from model output. I wasn’t the only one seeing this paper as flawed. It’s actually worse than we thought.
Guest essay by Patrick J. Michaels and Paul C. “Chip” Knappenberger, Center for the Study of Science, Cato Institute
There’s one thing that climate scientists of all stripes and flavors agree would be an unmitigated disaster: A sudden and dramatic melting of land ice, raising sea levels ten feet or so in a century.
Three years ago, it appeared that this monster had been put to bed by Denmark’s Dorthe Dahl-Jensen, when her team drilled all the way down through the ice to Greenland’s bedrock, providing the first reliable data from there concerning the warmest period in recent geological history, known as the Eemian. She found that for six thousand years (roughly from 122,000 to 128,000 years ago) summer temperatures in Northwest Greenland, where her ice core was extracted, averaged a whopping 11°F warmer than the 20th century average.
Remarkably, she estimated that Greenland only lost 30 per cent of its ice after six millennia. The integrated heat added to the ice over that span was roughly twenty times as much heat as humans could unload on it from greenhouse gases in 500 years, so the Greenland-driven apocalypse just isn’t going to happen.
Dahl-Jensen did note a curious mystery her work had uncovered. It’s well-known, from a number of independent sources, that Eemian sea levels were around twenty feet higher than the current era. Her ice-loss data suggested Greenland could only raise sea levels about one-third of that. The rest of the water had to come from the only other possible source, Antarctica.
The notion of an alarming rise in the ocean coming from there anytime soon has always been difficult to entertain. It is really cold down there and any melting should take a very long time—thousands of years—to do very much.
That just changed. Or at least it just changed in a complex and touchy simulation by Robert DeConto (University of Massachusetts) and David Pollard (Penn State) that made it above-the-fold on the front page of the March 31 New York Times. It seems that they shrunk the time for Antarctica to raise sea levels over ten feet a century from roughly the 50th century, to the 22nd (!).
Before the world gets all On The Beach-y about this, maybe there are devils hiding in the paper’s details. Indeed, there’s a forest of horns hidden in the dense but precise prose published in Nature.
For every predicted climate disaster, there has to be some type of climate model to project future temperatures. The authors used two (one for the ocean and the other for land). The first is a commonly employed general circulation model (GCM) from the National Center for Atmospheric Research in Boulder. The second is a less-common, smaller-scale “Regional Climate Model” (RCM) applied over the continent. These were then input into models of ice dynamics, including a new one that took rainfall (it really doesn’t rain in Antarctica now) and sloshed it into the continent’s huge glaciers, creating gigantic crevasses that crack truly ginormous hunks of ice off into the ocean. The new ice dynamics model is extremely sensitive to the settings of its large variety of handles and knobs—the settings of which can only be guessed at as the physics that the model is built upon is not well developed.
And a predicted disaster is only as reliable as the models that go into it.
The ice dynamics model is in its infancy, and the climate models used to generate temperatures around Antarctica are hot. Way too hot.
According to Andrew Monaghan (Ohio State), writing in Geophysical Research Letters: “20th century (1880–1999) annual Antarctic near-surface air temperature trends in the GCMs are about 2.5-to-5 times larger-than-observed.” Monaghan added this warming: “Until these issues are resolved, IPCC projections for 21st century Antarctic temperature should be regarded with caution.” We’re not sure the press got that memo.
Buried near the bottom of the supplementary material supplied to Nature, we can see that the climate model overproduction of warming infects the DeConto and Pollard paper as well. According to the authors, large areas of the continent (not just the well-known warming of the tiny Antarctic Peninsula that points towards South America) should have warmed some 7-15°F by now (Figure 1, left).
They didn’t. According to Ryan O’Donnell and others writing in the Journal of Climate in 2010, summer temperatures have risen since reliable records begin with the 1957 International Geophysical Year, but only about 5-10 per cent of what the RCM says should have been happening in many spots (Figure 1, right).
Figure 1. (left) Total temperature change between pre-industrial condition and the present produced by the DeConto and Pollard climate model; (right) observed trend (˚C/decade) in temperature from 1957-2006 determined by O’Donnell and colleagues (2011). Multiple the latter by five to get an idea of the total temperature change since 1957.
A good climate disaster also requires some guesstimates of how much carbon dioxide is going to increase in the future. The juiciest ones in the new paper assume atmospheric concentrations that even the United Nations’ has acknowledged as substantial outliers. And the paper lets it increase to eight times over the 19th century background, something no one we know has ever entertained as a basis for future climate scenarios. (We’re currently around four-tenths of the way to a doubling.)
There’s also a scenario where the increase in carbon dioxide is slower and more realistic, and—you guessed it—the end of the world is delayed by several centuries.
Anyway, hit the “send” button and throw all of these models into the computer, and compare to what (we think) happened in the Eemian. It’s there for all to see in the paper’s Figure 3a (our Figure 2): The concatenated models’ gargantuan increases in sea level take place about 1,000 years before they were actually observed.
So there it is. As University of Colorado’s Roger Pielke, Sr., tweeted in response to the paper:
Maybe this is what happens when hypersensitive models are fed unrealistic data.
References:
DeConto, R.M., and D. Pollard. 2016. Contribution of Antarctica to past and future sea-level rise. Nature, 531, 591-597, doi:10.1038/nature17145. http://www.nature.com/nature/journal/v531/n7596/full/nature17145.html
Monaghan, A. J., D. H. Bromwich, and David P. Schneider, 2008. Twentieth century Antarctic air temperature and snowfall simulations by IPCC climate models. Geophysical Research Letters, 35, L07502, doi:10.1029/2007GL032630.
O’Donnell, R., N. Lewis, S. McIntyre, and J. Condon, 2011. Improved Methods for PCA-Based Reconstructions: Case Study Using the Steig et al. (2009) Antarctic Temperature Reconstruction. Journal of Climate, 24, 2099-2115.
“And the paper lets it increase to eight times over the 19th century background, something no one we know has ever entertained as a basis for future climate scenarios.”
NASA GISS did and settled the science in Science back in 1971-
“It is found that even an increase by a factor of 8 in the amount of CO2, which is highly unlikely in the next several thousand years, will produce an increase in the surface temperature of less than 2 degrees K.”
Schneider, S. H., and Rasool, S. I., “Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate,” Science, Vol. 173, 9 July 1971, pp 138 – 141.
I just posted this link in Tips and Notes. It seems quite appropriate for this thread. I am glad to know that the science is settled.
http://fiostrending.verizon.com/tv/3/player/vendor/CNN/player/cnn/asset/cnn-nasa_study_says_ice_shelf_could_disappear_by_2020-cnn
I submitted the following comment . We’ll see if NYT lets it thru :
“It’s well-known, from a number of independent sources, that Eemian sea levels were around twenty feet higher than the current era.”
No it is not. This is a factoid, i e something that has been reported so often that everybody thinks it is true but which is actually extremely dubious. It goes back to Veeh (1960) who found that last interglacial corals throughout the Pacific and Indian Oceans were found consistently between +2 m and +10 m and selected 6 meters as an average.
Actually studies of tectonically stable, undeformed last interglacial shorelines far enough from icecaps to be unaffected by isostatic effects (e g Eyre Peninsula or West Australia) suggest that 2-3 meters is a more likely figure, i e more or less what you might expect from a partial melting of Greenland plus some termosteric rise.
And incidentally there is not a shred of actual evidence that the WAIS melted durin the last Interglacial, but a greeat deal of evidence that it didn’t..
Thanks a bunch. Very interesting because this would mean Dahl-Jensen explained all the rise with Greenland. Like I said, it’s very hard to melt much of Antarctica until you go to the millenial scale. And even the it’s difficult
Science, we hardly knew ye.
On April 1-st The New York Times printed an editorial called “The Danger of Runaway Antarctica” that was based on the DeConto and Pollard article in Nature. They also complain about sea level ruse and Hansen’s new allegations. Icould not let that stand so I sent the following letter to the editor of the New YorkTimes:
“To the Editor:
Your editorial today of a “Runaway Antarctica” based on the article by DeConto and Pollard in Nature, 531, 591-597, is asking us to believe in the dubious science of Climate Apocalypse they espouse. When you look at their paper you notice that their conclusions derive entirely from use of climate models. They use two in this case, one GCM (General Circulation Model) and one RCM (Regional Circulation Model). Before you place your trust in such models you should know that they have been in use by climate scientists since 1988 when James Hansen first introduced them. You would think from this that since they have been in continuous use for 27 years they should be a trustworthy tool for climate scientists to use. Unfortunately that is not the case. Every computer model there is, starting with the first one that Hansen used, has been giving wrong predictions about the coming global temperature. We know this because during 27 years there have been numerous opportunities to compare predictions with reality. All model predictions have been wrong, every single one of them. The usual errors have been overestimate of warming to be expected. The models used by DeConto and Pollard don’t disappoint us here and run true to form. GCM overestimates warming. The RCM actually surprises us by predicting rainfall (which does not exist in Antarctica) that sloshes into the continent’s huge glaciers, creating gigantic crevasses that crack truly enormous hunks of ice off into the ocean. I have said this before and I will say this again: time to close down the entire climate modeling operation and save money on supercomputers they use to create this trash. As to your other concerns, sea level rise is globally 2.46 millimeters per year (Chao, Yu & Li, Science, April 11, 2008). Anything more is local. Land could even rise locally as it does in Scandinavia. As to that paper by Hansen et al., just ignore him. His “climate science” has been proven erroneous repeatedly.”
Note: two typos in the original were corrected
Even psychics know never to go this far with predictions…..
Gullible Warming is amazing.