”We compare new observationally-based data sets of Antarctic near-surface air temperature and snowfall accumulation with 20th century simulations from global climate models (GCMs) that support the Intergovernmental Panel on Climate Change Fourth Assessment Report. Annual Antarctic snowfall accumulation trends in the GCMs agree with observations during 1960–1999, and the sensitivity of snowfall accumulation to near-surface air temperature fluctuations is approximately the same as observed, about 5% K−1. Thus if Antarctic temperatures rise as projected, snowfall increases may partially offset ice sheet mass loss by mitigating an additional 1 mm y−1of global sea level rise by 2100. However, 20th century (1880–1999) annual Antarctic near-surface air temperature trends in the GCMs are about 2.5-to-5 times larger-than-observed, possibly due to the radiative impact of unrealistic increases in water vapor. Resolving the relative contributions of dynamic and radiative forcing on Antarctic temperature variability in GCMs will lead to more robust 21st century projections.”
The above is the abstract from:
Monaghan, A. J., D. H. Bromwich, and D. P. Schneider (2008), Twentieth century Antarctic air temperature and snowfall simulations by IPCC climate models, Geophys. Res. Lett., 35, L07502, doi:10.1029/2007GL032630.
Roger Pielke Sr comments:
“This paper provides further evidence that the multi-decadal global climate models are significantly overstating the water vapor input into the atmosphere, and thus are not providing quantitatively realistic estimates of how the climate system responds to the increase in atmospheric well mixed greenhouse gases in terms of the water vapor feedback. This water vapor feedback is required in order to achieve the amount of warming from radiative forcing projected in the 2007 IPCC report.”
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Once more for the retention deficient, “20th century (1880–1999) annual Antarctic near-surface air temperature trends in the GCMs are about 2.5-to-5 times larger-than-observed”
Yes, that would certainly qualify as “significantly overstating” as per Pielke Snr. And as the hind casts back 120 years are 2.5 to 5.0 times larger than observed, can we then conclude that the projections out 120 years would also be subject to similar error?
This only shows that GCMs do not give a worthwhile output. Your model may be quantitive or qualitative but still the result is indeterminate. They will now tweak the parameters and say it is now correct, rubbish. Empirical data has shown warming for a long period, lately this seems to changing and the temperatures are dropping. Damn I was hoping for continued warming, cooling might win the argument but it will diminish the life of everyone more than warming.
Look on the bright side DHMO, policy makers are going to shorten our lives weather or no.
They’ll have us descend from the black mountain into the green valley at least two centuries with our SOL.
If it freezes our butts off for a bit they just might have to ease up and who knows? the horse may talk!
So it can melt !
Sediment cores reveal Antarctica’s warmer past
Researchers reported initial results from ANDRILL, a US$30-million international drilling project, on 16 April at the assembly of the European Geosciences Union in Vienna. During the past two years, the team has extracted two cores, each containing some 1,200 metres of sediment, from the seabed below the vast Ross Ice Shelf, a floating extension of the West Antarctic Ice Sheet. Together, the cores provide an almost uninterrupted 17-million-year record of Antarctica’s climatic past.
Palaeoclimatological records from ice cores, although more detailed and easier to interpret, cover only the past 800,000 years or so. Now, geologists say, Antarctica’s history is laid out much more clearly.
“We have every page of the book,” says David Harwood, an ANDRILL scientist at the University of Nebraska in Lincoln.
Sediments in the cores, along with microfossils such as pollen and spores, allow researchers to reconstruct sea temperatures and environmental conditions, such as the presence or absence of ice, over millions of years. The analytical work has only just begun, but early results indicate that, during warmer periods, the West Antarctic Ice Sheet and the Ross Ice Shelf shrank rapidly and substantially.
During a warm period some 3.5 million years ago, for instance, the ice sheet may have disappeared completely for around 200,000 years, raising sea levels globally by up to 10 metres.
http://www.nature.com/news/2008/080430//full/453013a.html