By Phil Plait
Global warming is real.
Let's get that out of the way right at the start. Climatologist Michael Mann's bombshell study from years back created the "hockey stick" graph, showing that in the past century, the Earth's overall temperature spiked, like a case of planetary flu. This study was immediately attacked by climate change deniers, who continue to flail away at it today. It has withstood these attacks, and is no longer seriously doubted by scientists who actually study the climate.
And now, a new study shows that this spike in temperatures is unprecedented going back over one hundred centuries. They looked at global temperature anomalies - deviations from an average or standard temperature - for 73 sites distributed across the planet, using fossils in sediments as a proxy for temperature. The chemical and isotopic composition of the fossils yields a fairly accurate measure of the environment temperature at the time the animal or plant making up the fossil lived.
What they found is simply stunning: The rate at which the globe is warming right now is far, far faster than it ever has going back as far as they could measure, up to 11,300 years ago. In fact, over the past 5,000 years, the Earth actually cooled by about 1.3 degree F . . . until the last 100 years, when our temperature spiked upwards by about the same amount.
Mind you, this is the rate of warming, how quickly the global temperature is increasing. But they also showed the actual temperature of the planet is warmer now than it has been for 70-80 percent of the past over that time period. There have been times when the Earth was warmer, but the important point isn't the actual temperature, but what it's doing.
And what it's doing now is skyrocketing.