Twenty Years Ago, James Hansen May Have Been Right

Headless does us all a favor, with a graph (!!) for science-knownothings like me.

First, at the time of Hansen’s testimony (the blue dot), his temperature data demonstrated an exceptionally strong correlation with atmospheric CO2. Based on this limited data, he had reason to be alarmed at that time. It should be noted that the superimposed actual CO2 plot tracks Hansen's projected 1988 to 2008 worst case plot fairly closely.

However, his projections of temperatures after 1988 show that his model broke down almost precisely when he testified. This could be due to a saturation effect for CO2 at that level or (more likely) shows Hansen got lucky with his early model and his CO2-temperature relation from 1964 through 1988. There may really be nothing there, except a coincidence.

I’ll add that there was indeed a modest amount of global warming from 1988 to 2001, with a plateau through 2006 that was about 0.2 degrees Celsius warmer than 1988. But global temperatures have since declined. Declined so much that the average global temperature is now 0.2 degrees Celsius less than 1988, not the 0.7 degrees higher that Hansen predicted. A difference of minus 9 tenths of a degree Celsius.

Which is why the mantra is now "climate change" rather than 'warming.' Hansen's acolytes can read, too.

Wanna see the graph? Go visit Headless' site.