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10 August 2008 Blog Home : August 2008 : Permalink

Climate Change in the Australian

The Australian newspaper had an article yesterday about climate change skeptics. It does a fairly good job of explaining why many of us are skeptical but does a poor job of explaining the facts in a "skeptic friendly" way. For example discussing UHI and  surfacestations.org it gives the last word to Hanson and doesn't really explain that many skeptics are very suspsicious of the GISS adjustment techniques:

"Land-based temperature readings are corrupted by the urban heat island effect," he says. "Urban areas encroaching on thermometer stations warm the micro-climate around the thermometer due to vegetation changes, concrete, cars and houses."

As such, he alleges that the GISS figures - which are enormously influential in the climate change debate - are "hopelessly corrupted" and may even be manipulated to suit Hansen's views on global warming.

A group of weather buffs in the US also has attacked GISS's methodology, putting together an online photo gallery of US weather stations at website www.surfacestations.org that shows some thermometers situated next to asphalt runways and parking lots where they would pick up excess warming.

But GISS says the distorting impact of this urban warming is negated because data from these stations is modified to remove these effects and give a true reading. Hansen acknowledges there may be flaws in the weather station data because temperature measurement is not always a precise science. But he says this does not mean big-picture trends can't be drawn from the data.

He says: "That doesn't mean you give up on the science and that you can't draw valid conclusions about the nature of earth's temperature change."

Then in discussing the GISS Y2K correction it says merely before quoting Rush Limbaugh:

Hansen has been infuriated by the attacks on GISS by climate change critics. Last year Canadian blogger and retired businessman Stephen McIntyre exposed a minor mistake in Hansen's figures that had caused GISS to overstate US temperatures by a statistically small 0.15C since 2000.

The point is not the overstatement directly but the fact that this overstatement meant that the "hottest year" leader board now became heavily dominated by the 1930s instead of 1998-2006. In other words contrary to various greenshirt screaming US temepratures are essentially unchanged over a 70+ year cycle (see below for more). Given that, as the article notes elsewhere, atmospheric CO2 levels have risen significantly during this period this looks like evidence against the CO2 causes global warming argument.
Contiguous 48 state US temperatures
If we look at the GISS US temperature chart for the last 100 years we see that it has some clear phases. A rise during the 1920s peaking in the 1930s then a general decline bottoming out in the 1970s followed by a rise again in 1980s and 1990s. If various predctions are correct we will now see a decline in the 2010s. The question is going to be whether that decline continues into the 2020s and 2030s before reversing or whether it reverses earlier.

The same goes for the general cooling period we are in now. We get the skeptic case made poorly and then a climate scientist saying 10 years isn't long enough to draw conclusions. I'm glad the Australian published the article and provided links and names so that readers can investigate bit I'm a bit annoyed that the objections appear like strawmen targets that global warming believers can easily debunk (e.g. the picking of temperatures from 1998). On the other hand it would be churlish to complain too much. The Greenland is less green now than it was c. AD 1000 point is made without any good rebuttal from a global warming believer and is made early so those who skim the article are likely to take that point away.