Stanford climate scientists forecast permanently hotter summers beginning in 20 years
"We also analyzed historical data from weather stations around the world to see if the projected emergence of unprecedented heat had already begun," Diffenbaugh said. "It turns out that when we look back in time using temperature records, we find that this extreme heat emergence is occurring now, and that climate models represent the historical patterns remarkably well."
Noah Diffenbaugh, assistant professor of environmental Earth system science
And here you have one of the biggest problems facing this analysis.
Weather Stations Giving Bad Global Warming Data -- MSM MIA October 01, 2007
And it seems Noah has been down this road before...
Climate model predicts dramatic changes for US over next 100 years; NASA says warmer world may not be a wetter one Oct 22, 2005
The climate model, run on supercomputers at Purdue University, takes into account a large number of factors that have been incompletely incorporated in past studies, such as the effects of snow reflecting solar energy back into space and of high mountain ranges blocking weather fronts from traveling across them, said Noah S. Diffenbaugh, the team's lead scientist.
Dr. Noah S. Diffenbaugh