In short, one of the fundamental cornerstones of climate skepticism was found to be significantly flawed. Once the corrections were made, it is interesting to note that the UAH-MSU dataset matched much more closely the predictions made by climate models.

The three preceding links are a bit beyond me technically. That being said, they are dated 1998, 1999 and 2002. His latest data and study suggesting wide spread differences in predicted and real temperatures was well after that. But for arguments sake lets say he isn't remotely close to correct, that doesn't change the fact that predictions of AGW doom and gloom have been completely off.


Regarding Dr. Hansen


In a global temperature update through 2012 [PDF], James Hansen and his colleagues at NASA's Goddard Institute for Space Studies report:
The 5-year running mean of global temperature has been flat for the past decade (emphasis added). It should be noted that the "standstill" temperature is at a much higher level than existed at any year in the prior decade except for the single year 1998, which had the strongest El Nino of the century. However, the standstill has led to a widespread assertion that "global warming has stopped".
Global Warming at a "Standstill" Admits Man-Made Warming Proponent Hansen - Hit & Run : Reason.com