Bering Sea floor sheds light on last major global warming period
By ANIWednesday, January 5, 2011
WASHINGTON - Researchers at the University of California at Santa Cruz have found that the sediments at the bottom of the Bering Sea indicate that that the region was ice-free all year and animal life was rich during the last major warm period.
The Pliocene warm period lasted from 3.5 to 4.5 million years ago, just before the Earth went into a repeating cycle of ice ages and bears the closest resemblance to the world that is now resulting from global warming.
“It’s the first time we’ve got sediments from that far back,” Discovery News quoted Christina Ravelo as saying.
She said that the sea is extremely sensitive to climate changes and has revealed some surprises about what it was like during the last big warming event.
Ravelo revealed that sea was not neatly layered - with the coldest waters on the bottom and the warmest on the top, as is expected of oceans in warmer times.
“I think that’s generally true in lower latitudes. But in high latitudes it’s very sensitive to salinity,” Ravelo said.
In the Early Pliocene’s Bering Sea, there was loads of productivity, probably due to strong winds stirring things up on an ice-free sea.
However, it’s not clear how much this information will help us understand future global warming.
The carbon dioxide levels during the height of the Pliocene warm period were about where today’s levels are, Ravelo said.
But the levels as of now are still rising, and it’s all happening much faster now than in the past.
That said, there are some things in the future that are likely to look a lot like that particular time in the past, said Mark Pagani, a geology professor and researcher at Yale University.
“The early Pliocene is now considered a model for future warming…dramatically higher sea levels, temperatures 3 to 4 degrees C warmer than today, with CO2 levels comparable to modern values,” he said.
“The lesson we take from this is that the Earth has a relatively high climate sensitivity to CO2 and we can expect future warming over the next few centuries even if CO2 levels are held at current levels.”
The results were reported at the recent meeting of the American Geophysical Union. (ANI)
