Posts Tagged ‘climate history’
|In this week’s issue of Nature: “Earth’s biggest climate switch”
Thursday, October 22nd, 2009
A lot of us have been following the paleoclimatology literature examining changes in global temperatures and atmospheric CO2 over the past 60 million years, which can be deduced using different chemical signatures in ocean sediment cores.
One time period, in particular, is especially relevant to the discussion of rising CO2–a change between 33.5-34 million years ago (MYA) called the Eocene-Oligocene (E-O) transition.
What happened back then? Around this time was the first appearance of consistent polar ice on Antarctica. Before then, atmospheric CO2 levels were high enough that Earth’s climate was a hothouse, perhaps as much as 8-10 degrees C warmer than today. Antarctica was lush and green with forests.
The worry is that if we start approaching atmospheric levels of CO2 similar to those before the E-O transition, we may warm the climate to a condition where polar ice us unstable. That would be bad news because the loss of the Antarctic ice sheet would raise sea level by more than 60 meters.
This week, Paul Pearson and colleagues (who have done a lot of this great work) published a new article1 examining the E-O transition in more detail to see if it has any clues for our modern environmental challenges.
What did they find?
Tags: Antarctica, climate history, ice
Posted in climate change science, polar ice | No Comments »
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