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-Gisstemp – Global Temperature at “Tipping Point”?
James Hansen, the 68 year old icon of climate research from the NASA Goddard Institute for Space Studies (NASA GISS), has brought off another coup to combine his science with political alarmism. “We compare global temperature reconstructions of GISS, NCDC, and HadCRUT. We conclude that global temperature continued to rise rapidly in the past decade, despite large year-to-year fluctuations associated with the El Nino-La Nina cycle of tropical ocean temperature.”
draft of “Current GISS Global Surface Temperature Analysis”, dated March 19, 2010. But he plows a lonely furrow, using his GISS co-authors R. Ruedy, M. Sato, and K. Lo .
Co-author R. Ruedy wrote in his August 3, 2007, email to his co-worker at GISS and RealClimate blogger Gavin Schmidt:
The United States Historical Climate Network] data are not routinely kept up-to-date (at this point the (sic) seem to end in 2002)…NASA’s assumption that the adjustments made the older data consistent with future data … may not have been correct.
He claimed that this introduced an estimated warming into the [U.S.] record of 0.1 deg C. Ruedy then described an alternate way of manipulating the USHCN temperature data in line with the Global Climate Network (GHCN), “a more careful method they might consider using, instead.”
The above graph shows that these changed U.S. records cannot account for the huge difference between GISS global temperature and GHCN’s own global temperature analysis. The slope of NCDC (NOAA) for the past 13 years indicates a warming of a mere 0.08°C although the graph ends during the ongoing El Nino. During the same time, Gisstemp indicates a wooping +0.17°C.
The said GISS analysis gloats with the following bold statement:
The reality of continued global warming contrasts sharply with a frequently heard assertion that the world has been in a cooling trend for the past decade or at least ‘global warming stopped in 1998′.
Let’s see how they back up their conclusion of a “rapid warming” worldwide during the past decade when at the same time, the U.K. “hadCRUT” dataset shows in fact no significant warming/cooling, not just since 1998 but even since the El Niño neutral year of 1997 (+0.01°C in 13 years)! Needless to say that no warming occured in the satellite records during the same time. When it comes to satellite data, Giss again is highly selective. They claim that their intrapolation and extrapolation of data from arctic (mostly coastal) weather stations into remote areas in the Arctic within 1200 km (Greenland, Arctic ice shield) are backed up by satellite data. The question is which data? They also claim that the difference between the HadCRUT [no warming] and the Giss contineous warming until 2010 is mainly due to their full coverage of the Arctic region [even where they have no data on their 1x1° gridboxes]. The 5×5° gridboxes of HadCRUT also intrapolate and extrapolate data into more northern regions, but leave out large areas blank which are later filled with the average of the Northern Hemisphere (NH) according to James Hanson.
The following warmings occured during the 1997-2009 period (Excel-slope):
HadCRUT NH: +0.11°
Uah Arctic (60-85°N): +0.70°
GISS Arctic (64-90°N): +1.28°
Discussion
Here is just an example of how I understand it is being done: If Svalbard (Spitzbergen), the temperature badly situated on a more and more busy airport indicates a warming of 1°C, this warming is being extended to an area within 1200 km by Giss into remote areas of the Arctic Sea. The Hadley Centre, on the other hand, uses the +0.11° warming of NH for those remote areas that are not within the 5×5° gridbox of HadCRUT3 near any such station. Now, it is a well known fact that winter temperatures in stations of Northern America and Eurasia react very sensitive to urban heat influences. The fact that the projected Giss records give an additional Arctic warming of 83% compared to the UAH satellite data make it clear how easy it is to be biased about polar temperatures, depending if you come from the warmers, the lukewarmers or the CAGW denying camp. Some may have noticed that the two Arctic projections don’t cover exactly the same area (60-85°N vs. 64-90°N). But I don’t think this would make such a significant difference.
It is easy to bring about other skeptical arguments such as dirty snow in Alaska stations being projected into areas with pristine snow and may be no warming, coastal stations, which lost Sea ice in Summer by 2007, are being projected into areas with continuous summer ice, and so on. My belief is that the claimed, enhanced Arctic warming is in fact Arctic urban, coastal and lost sea ice warming. This my conclusion can easily be supported by the independant temperature recordings of the 80°-90° polar circle No warming occured during the Summer months. No prolonged melting season can be distinguished when comparing any of the recent years with years of the fifties and sixties. But polar winter can have sudden drops and rises of temperatures up to 20° or more. Please see and plot the daily polar temperatures for each year by yourselves, at the Danish DMI Centre for Ocean and Ice.
Which is better, to fill in the remote-area grid cells with 0.11° (HadCRUT) or with 1.28° (Giss) warming? There is an interesting discussion going on at http://wattsupwiththat.com/2010/05/21/visualizing-arctic-coverage/. Both methods are scientifically backed up to be the most accurate. Yet, the results are way apart. Watt else?!
GISS-NASA-temperature trendtrend over the poles 1997-2009 with a smoothing radius of 250 km. Areas not covered by measurements stay grey on this scale.
GISS-NASA-temperature trendtrend over the poles 1997-2009 with a smoothing radius of 1200 km resulting in full polar coverage and thus leading to the official GISS-temperature trend
