Jim Hansen of the Goddard Institute of Space Studies in New York, has the reputation of having started the greenhouse scare by his testimony before the US Senate on June 23rd 1988 when he presented results which purported to show that the surface of the earth was warming. He had assembled temperature data from meteorological measurement stations and shown that the "mean temperature anomaly", the deviation from a ten-year average, was increasing in a rather irregular fashion. He assumed that the cause was an increase of greenhouse gases emitted by humans.

 

This proposition has become accepted as gospel, despite many questions that should be asked.

 

Hansen's  results applied only to the land surface of the earth, 29% of the total. Although there were many temperature measurements by ships of the  sea surface, Hansen, for many years, regarded them as so unreliable that he felt unable to use them to calculate a truly global temperature change.

 

The land-based measurements themselves were biased since they were mostly made close to cities where population, buildings and vehicle usage provided an upwards trend. There were very few measurements in unpopulated areas.

 

In 1985 a paper by Folland and Parker proposed a method for using sea surface temperature measurements which was taken up by Phil Jones of the University of East Anglia in Britain to provide a mean global surface temperature anomaly graph. This graph is the basis of the claim for global surface warming of the Intergovernmental Panel on Climate Change (IPCC). Hansen and his US colleagues have never accepted the validity of this method. Instead they have derived a combined sea surface temperature set based on a combination of satellite data and the ship measurements. Despite this, Hansen and his fellow US compilers are largely ignored by the IPCC .

 

Hansen has now published a major article for the "Scientific American", March 2004, Volume 290, pages 40-49. A longer version of the article is available from http://www.sciam.com/on the web   A claimed 14.75 MB seems to reduce to 333KB if you are registered, but a similar article has been published at

 

 http://naturalscience.com/ns/articles/01-16/ns_jeh.html> and

 

 <http://pubs.giss.nasa.gov/docs/2003/2003_Hansen.pdf> (1.4 MB)

 

From the title  "Defusing the Global Warming Time Bomb" he would appear to be expressing 100% support for the IPCC. However, there are several aspects of the article which question IPCC attitudes, but all too diffidently, and others where he contradicts himself.

 

"the world has begun to warm at a rate predicted by climate models".

 

Now this is simply not true. The models have so many adjustable parameters that they can be fitted to Hansen's temperature anomalies by fudging, but the models have no record of successful prediction. Indeed, Hansen agrees with me when he categorises the IPCC projections as "pessimistic" and presumes to substitute his own, more realistic projections. Of course, ALL of the IPCC projections are not only pessimistic, but deliberately exaggerated, and they always were. He makes a  comment. " It remains to be proved whether the smaller observed growth rates are a fluke, soon to return to IPCC rates, or are a meaningful difference"

 

In talking about efforts which need to be made to reduce greenhouse emissions he, predictably, does not dare mention the most effective method for reducing methane emissions; a continuation of the current trend to drain wetlands..

 

He quotes a common objection to his temperature record:

 

"The surface warming is mainly urban 'heat island' effects near weather stations"

 

His answer to this objection is

 

"Not so. As predicted, the greatest warming is found in remote regions such as central Asia and Alaska. The largest areas of surface warming are over the ocean, far from urban locations. (see maps at www.giss.nasa.gov/data/update/gistemp)"

 

To try and argue that Russian or Alaska weather stations are free from heat islands because they are assumed to apply to vast unpopulated areas is simply not valid.

 

The suggestion that sea surface temperatures are more reliable than land-based results is the complete opposite of what Hansen has been saying in the past, and to suggest that the sea surface temperatures are higher than those of the land is a lie, as I have pointed out in my Climate Truth Newsletter No 39. The mean global temperature rise (according to NOAA/NCDC) over the oceans (71% of the earth's surface) from 1975 to 2000 was only about 0.4°C, whereas the rise over land (29% of the earth's surface) was double, about 0.8°C.This is evidence of upwards bias in the land measurements. still express amazement that they still try to compare the Northern Hemisphere with the Southern Hemisphere when the actual contrast is between land-based and sea-based measurements.

 

Hansen still quotes the land+sea measurements (biased by the land component) for his estimate of the global temperature rise. If he quoted only the sea surface rise he could not be quite so confident of the "reality" of global warming, and its inability to be explained by natural climate factors.

 

Of course, the sea surface temperature measurements have an upwards bias as well. If they were corrected we might end up with a temperature record for the surface which is similar to that shown in the lower troposphere by the satellites and weather balloons, a record which is quite capable of being explained by natural causes, of which the most recent have been El Niño effects, creating a temporary upwards trend.

 

 

Vincent Gray
75 Silverstream Road
Crofton Downs
Wellington 6004
New Zealand
Phone/Fax (064) 4 9735939
Email vinmary.gray@paradise.net.nz
"It's not the things you don't know that fool you.
It's the things you do know that ain't so"
Josh Billings