After years of controversy, at last we’ve got incontrovertable proof of manmade Global Warming!

Errors introduced into data being added to the GISS surface temperature database for the U.S. ended up increasing temperatures in the U.S. by about 0.15 °C (0.27 °F) over the last 20 years. The mistakes, named “Hansen’s Y2K error” after NASA’s Dr. James Hansen (Director of the Goddard Institute for Space Studies, science advisor to Al Gore’s movie An Inconvenient Truth, and contributor to Clinton/Gore, and Kerry/Edwards presidential campaigns), were very convenient for the warming advocates, but at present appear to have been caused by human error that simply went undetected for years. As to why the error’s named after Hansen, the reasons are many and varied, but you can start here for a quick primer.

Well, last week Steve McIntyre of Climate Audit blogged that he had found and the corrected the errors. As a result of McIntyre’s work, 1998 is no longer the hottest year on record—1934 is! In fact, the decade of the 30s averaged 0.5 °C (0.9 °F) above normal while the 90s only averaged 0.424 °C (0.763 °F). Six of the ten hottest years occurred before 1955.

Here’s the new Top Ten list (hottest first):

Note that the temps in the table are not the actual high temperatures for each year (if they were, we’d be talking about global freezing, not warming!). They are the amount in °C (°F) that an average of the temperatures for a particular year was above statistical normal.

Hansen’s error increased temps in the last 20 years by 0.15 °C on average (some stations had errors as high as 1 °C (1.8 °F), others were the same in the negative direction, but the average amounted to an increase of 0.15 °C).

The following graphic is an animation comparing the old GISS temp curve with the corrected curve:

Click on the image to see a larger version. The source images used in the animation came from here.

Once again, the GISS temp data shows how much temperatures were above or below statistical normal. Called "anomalies", the temps that aren’t normal fall between a +1.5 and -1.5 °C (+2.7 and -2.7 °F) band. The red lines show the running 5-year average (or mean) of the anomalies. Notice how the majority of the errors fall conveniently between 1990 and 2000.

Some people are trying to trivialize the change, saying it doesn’t make “much difference”, but as the vaunted Kyoto Protocol is only supposed to reduce temps 0.07 °C by 2050 at a cost of billions of dollars, Steve’s correction is quite an accomplishment.

On his own, Steve McIntyre has reduced temps in the U.S. by 0.15 °C—more than Kyoto ever could!

Tags: blog | weblog | global warming | science | climate change | junk science