Earth Warmer Now Than Most of Past 11,000 Years

The average global temperatures in the past decade is higher than it has ever been in the past 11,300 years, according to a study published Thursday in the journal Science.

This study in the evolution of the Earth’s temperatures during the Holocene – the relatively balmy period that began after the last major ice age ended and encompasses all of recorded human civilization – offers a long-term context for assessing the current climate change.

According to the research, a one-degree temperature variation that took 11 millennia to occur since the end of the last major ice age has now been replicated in 150 years, since the early days of the Industrial Revolution.

In the same framework, the decade 2000-2009 was one of the warmest since modern record-keeping began, but global mean temperatures didn't breach the levels of the early Holocene. Now they are on track to do so, according to the Science paper. If the scientists' forecasts are right, the planet will be warmer in 2100 than it has been for 11,300 years.

Carried by researchers from Oregon State University and Harvard University and funded by the U.S. National Science Foundation, the project also surveyed a crucial question: Is the spike in global temperature recorded in the past 150 years unusual—the result of greenhouse-gas emissions from human activity—or can it be explained as natural, long-term variations in temperature?

The study points to human activity as the cause, because of the suddenness of the shift in temperature which appears to be out of whack with long-term trends.

"What's different is the rate of change," said Shaun Marcott, a paleoclimatologist at Oregon State University and lead author of the paper. "What we've seen over the past 150 years is much greater than anything we saw in the past 11,000 years."