climate models overestimated global warming

That’s the upshot of a new study in the journal Nature Climate Change that compared 117 climate predictions made in the 1990's to the actual amount of warming. Out of 117 predictions, the study’s author told FoxNews.com, three were roughly accurate and 114 overestimated the amount of warming. On average, the predictions forecasted two times more global warming than actually occurred.
Some scientists say the study shows that climate modelers need to go back to the drawing board.
"It's a real problem ... it shows that there really is something that needs to be fixed in the climate models," climate scientist John Christy, a professor at the University of Alabama in Huntsville, told FoxNews.com.


But John Christy says that climate models have had this problem going back 35 years, to 1979, the first year for which reliable satellite temperature data exists to compare the predictions to.
"I looked at 73 climate models going back to 1979 and every single one predicted more warming than happened in the real world," Christy said.
Many of the overestimations also made their way into the popular press. In 1989, the Associate Press reported: "Using computer models, researchers concluded that global warming would raise average annual temperatures nationwide 2 degrees by 2010."
But according to NASA, global temperature has increased by less than half that -- about 0.7 degrees Fahrenheit -- from 1989 to 2010.

he study also says that an overestimate of the power of CO2 as a greenhouse gas could be why the models over-predict, but that they do not know why the models are wrong at this point.
Christy said he is not optimistic about the models being fixed.
"The Earth system is just too complex to be represented in current climate models. I don’t think they’ll get it right for a long time."



Read more: http://www.foxnews.com/science/2013/09/12/climate-models-wildly-overestimated-global-warming-study-finds/#ixzz2eoqeQVTu