NASA climatologist James Hansen has produced new research that ties the record heat waves the world has experienced over the past decade to climate change.Hansen's paper will be published today, and in an Op-Ed in the Washington Posthe previewed his findings. He and his colleagues analyzed 60 years of weather patterns and have found that extremely hot summers are increasing in frequency.Hansen writes: This is not a climate model or a prediction but actual observations of weather events and temperatures that have happened. Our analysis shows that it is no longer enough to say that global warming will increase the likelihood of extreme weather and to repeat the caveat that no individual weather event can be directly linked to climate change. To the contrary, our analysis shows that, for the extreme hot weather of the recent past, there is virtually no explanation other than climate change. The deadly European heat wave of 2003, the fiery Russian heat wave of 2010 and catastrophic droughts in Texas and Oklahoma last year can each be attributed to climate change. And once the data are gathered in a few weeks’ time, it’s likely that the same will be true for the extremely hot summer the United States is suffering through right now.This conclusion is based on hard numbers, Hansen says. And in his analysis, he doesn't seem to leave any room for the argument that the patterns he's uncovered are naturally-occurring. The odds that natural variability created these extremes are minuscule, vanishingly small. To count on those odds would be like quitting your job and playing the lottery every morning to pay the bills.The paper is scheduled to be published in the peer-reviewed Proceedings of the National Academy of Sciences. But it's worth noting that otherrecent research--from researchers affiliated with the National Oceanic and Atmospheric Association--determines that there's no conclusive link between recent heat waves and floods and climate change. "After all, there has always been extreme weather," the paper notes.