Climate change is indeed a culprit for recent record-setting summer temperatures, according to a NASA report published on Monday in the journal Proceedings of the National Academy of Sciences. The study shows how extreme temperatures, once considered anomalous, are increasingly normal occurrences. "Such anomalies were infrequent in the climate prior to the warming of the past 30 years, so statistics let us say with a high degree of confidence that we would not have had such an extreme anomaly this summer in the absence of global warming," the report’s lead author, James Hansen, says. Hansen is head of NASA’s Goddard Institute for Space Studies in New York and one of the world’s leading, and most politically outspoken, climatologists.

[Video courtesy of NASA/Goddard Space Flight Center GISS and Scientific Visualization Studio. "Earth's Northern Hemisphere over the past 30 years has seen more 'hot' (orange), 'very hot' (red) and 'extremely hot' (brown) summers, compared to a base period defined in this study from 1951 to 1980. This visualization shows how the area experiencing 'extremely hot' summers grows from nearly nonexistent during the base period to cover 12 percent of land in the Northern Hemisphere by 2011. Watch for the 2010 heat waves in Texas, Oklahoma and Mexico, or the 2011 heat waves the Middle East, Western Asia and Eastern Europe."]