Whatever the cause, it's clear that the world is getting warmer. NASA recently published a study which found that he average global temperature has climbed by about 0.8°Celsius (1.4° Fahrenheit) since 1880. The debate over the why and how behind the increase continues to generate a different kind of heat - political heat. Indeed, the newly-installed head of the House Energy and Commerce Committee said the other day that global warming is not connected to human activity. Yet at the same time, the NASA study found that about two-thirds of the warming of the globe has occurred since 1975.
To see this graphically, check out the images NASA has collected to underscore some fairly dramatic shifts in the Earth's climate system.
