Since End Of Last Ice Age, Rates Of Global Warming 'Amazing And Atypical' | WAMU 88.5 - American University Radio
Filed Under:

Since End Of Last Ice Age, Rates Of Global Warming 'Amazing And Atypical'

Play associated audio

There's plenty of evidence that the climate has warmed up over the past century, and climate scientists know this has happened throughout the history of the planet. But they want to know more about how this warming is different.

Now a research team says it has some new answers. It has put together a record of global temperatures going back to the end of the last ice age — about 11,000 years ago — when mammoths and saber-tooth cats roamed the planet. The study confirms that what we're seeing now is unprecedented.

What the researchers did is peer into the past. They read ice cores from polar regions that show what temperatures were like over hundreds of thousands of years. But those only reveal changes in those specific regions; cores aren't so good at depicting what happened to the whole planet. Tree rings give a more global record of temperatures, but only back about 2,000 years.

Shaun Marcott, a geologist at Oregon State University, says "global temperatures are warmer than about 75 percent of anything we've seen over the last 11,000 years or so." The other way to look at that is, 25 percent of the time since the last ice age, it's been warmer than now.

You might think, so what's to worry about? But Marcott says the record shows just how unusual our current warming is. "It's really the rates of change here that's amazing and atypical," he says. Essentially, it's warming up superfast.

Here's what happened. After the end of the ice age, the planet got warmer. Then, 5,000 years ago, it started to get cooler — but really slowly. In all, it cooled 1.3 degrees Fahrenheit, up until the last century or so. Then it flipped again — global average temperature shot up.

"Temperatures now have gone from that cold period to the warm period in just 100 years," Marcott says.

So it's taken just 100 years for the average temperature to change by 1.3 degrees, when it took 5,000 years to do that before.

The research team tracked temperature by studying chemicals in the shells of tiny, fossilized sea creatures called foraminifera. Their temperature record matches other techniques that look back 2,000 years, which supports the validity of their much longer record.

Climate scientists predict that the current warming will continue, given the amount of greenhouse gases going up into the atmosphere.

"The climate changes to come are going to be larger than anything that human civilization and agriculture has seen in its entire existence," says Gavin Schmidt, a climate researcher at NASA's Goddard Institute for Space Studies. "And that is quite a sobering thought."

The research appears in the journal Science.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

NPR

FX's 'The Bridge' Finds Authenticity In Spanish-Language Scenes

NPR's TV critic Eric Deggans visited the set of FX's cross-border crime drama, discovering the way the show's Spanish-language scenes help reveal new dimensions to the series' Mexican characters.
NPR

From Kale To Pale Ale, A Love of Bitter May Be In Your Genes

Researchers have found a gene that affects how strongly you experience bitter flavors. And those who aren't as sensitive eat about 200 more servings of vegetables per year.
NPR

Transcript: Sen. Warren's Full NPR Interview On Financial Regulation

Warren tells Morning Edition that audio tapes made by an investigator working for the New York Fed reenforce the perception of a disturbingly cozy relationship between regulators and banks.
NPR

'Ello' Aims For A Return To Ad-Free Social Networking

Ello is the viral social network of the moment. Ad free, invite only and with the option of anonymity, it's generating tons of chatter as the latest alternative to Facebook.

Leave a Comment

Help keep the conversation civil. Please refer to our Terms of Use and Code of Conduct before posting your comments.