At Today's Levels Of Atmospheric Carbon, Pliocene Arctic Was 10C Warmer Than Now - New Scientist

[hatrack]

With carbon dioxide levels close to our own, the Arctic of the Pliocene epoch may have warmed much more than previously thought – and the modern Arctic could go the same way. Ashley Ballantyne at the University of Colorado, Boulder, and colleagues analysed 4-million-year-old Pliocene peat samples from Ellesmere Island in the Arctic archipelago to find out what the climate was like when the peat formed.

At that time, CO2 levels are thought to have been close to current levels – around 390 parts per million – but global temperatures were around 2 to 3 °C warmer than today. It was the last warm period before the onset of the Pleistocene glaciation, and is used by climate researchers as a model for our future climate. Previous studies using computer models have suggested that the Pliocene Arctic was also warmer than it is today – up to 10 °C warmer. A little warming can trigger a lot more in the Arctic because the loss of light-reflecting sea ice and the spread of plants across the land increase the amount of solar energy that is absorbed.
Peat heat

Ballantyne's team estimated the temperature of the period at which the peat formed by measuring three things that are affected by temperature: the concentration of various chemical compounds, levels of a certain isotope in tree rings and the amount and types of fossilised vegetation. The group's analysis suggests the samples formed when average local temperatures were about -0.5 °C. That is 19 °C warmer than temperatures today – more than the previous computer models had estimated.

"These results should be alarming," says Ballantyne. Although it could take centuries for current global temperatures to respond to rising CO2 levels, we can expect the Arctic to warm much more than the rest of the planet, he says.

EDIT

http://www.newscientist.com/article/dn19155-soaring-arctic-temperatures--a-warning-from-history.html

[Warpy]

1. That's exactly what is happening

because warming is much more pronounced at higher latitudes while the lower latitudes are seeing wider extremes in weather patterns.

[pscot]

2. 18 degrees fahrenheit

That's a game changer for sure.

[joshcryer]

3. You don't say?

CO2 can't cause this level of warming! What utter nonsense. Nothing to see here, move along.

[XemaSab]

4. Pass the salt.

:popcorn:

[Dogmudgeon]

5. The process was slower in the Pliocene

More time to allow a proper accumulation of heat at the North Pole (and possibly the South, as well). I'm sure that the North Pole would have been ice-free then.

The next phenomenon I'm keeping an eye out for will be a dramatic increase in weather activity in the extreme north, possibly with a stormy inter-cell (as in "Hadley Cells") convergence zone at 65-75 degrees north latitude. I would also not be surprised if the North Pole itself was warmer than this new ICCZ. (Well, in the case of the pole itself, the sea surface temperature anomaly.)

Of course, I also thought that it would take until 2030 until the Northwest Passage would open up. I was off by 23 years.

It's a frighteningly good time to be a climatologist! Who'd'a thunk that Woods Hole and Lamont-Doherty would ever become "sexy"?

--d!