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Published: Wednesday 21 August, 2013

longchamp le pliage black large longchamp le pliage black large Global warming 55m years ago triggered by changes in Earths orbit

Changes in the Earth orbit 55million years ago caused the planet to warm up by 5C, according to new research.

A study by climate scientist Rob DeConto of the University of Massachusetts Amherst and colleagues at the University of Sheffield found that orbital changes triggered the melting of vast areas of permafrost at the poles, which released greenhouse gas carbon dioxide into the atmosphere.

are instead ascribing the carbon source to the continents, in polar latitudes where permafrost can store massive amounts of carbon that can be released as carbon dioxide when the permafrost thaws.

Grass is greener: Thawing permafrost on the North Slope along the Sagavanirktok River near Deadhorse, Alaska


Many scientists have long suspected that rising levels of carbon dioxide and the global warming that ended the last Ice Age were somehow linked, but establishing a clear causeandeffect relationship between carbon dioxide and global warming from the geologic record has remained difficult.

But a new study, published in Nature, identifies this relationship and provides compelling evidence that rising carbon dioxide caused much of the global warming.

Up to now carbon dioxide role was unclear because the Earth began warming before levels of the gas in the atmosphere began to rise.

But now Jeremy Shakun from Oregon State University has worked out what happened.

He believes that changes in the Earth orbit melted northern ice sheets, which meant that fresh water flowed into the Atlantic Ocean and stopped the circulation of warm currents.

the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere, Shakun said.

warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the carbon dioxide out of the deep water, and released it into the atmosphere. That, in turn, would have amplified warming on a global scale.

Orbit affects the amount, location and seasonality of solar radiation received on Earth, which in turn affects the seasons, particularly in polar latitudes, where permafrost and stored carbon can accumulate.

They then simulated climateecosystemsoil interactions, accounting for gradually rising greenhouse gases and polar temperatures plus the combined effects of changes in Earth orbit.

Their results show that the magnitude and timing of the PETM can be explained by the orbitally triggered decomposition of soil organic carbon in the circumArctic and Antarctica.

DeConto and colleagues said that this massive carbon reservoir at the poles had the potential to repeatedly release thousands of petagrams of carbon to the atmosphereocean system once a longterm warming threshold was reached just prior to the PETM.

Until now, Antarctica, which today is covered by miles of ice, has not been appreciated as an important player in such global carbon dynamics.

While the amounts of carbon involved in the ancient soilthaw scenarios was likely much greater than today, DeConto warned that fossilfuel burning is speeding up the thawing of permafrost.

He said: Similar dynamics are at play today. Global warming is degrading permafrost in the north polar regions, thawing frozen organic matter, which will decay to release CO2 and methane into the atmosphere. This will only exacerbate future warming in a positive feedback loop.

Results of the study are reported in Nature.

Re: John, Portsmouth UK, 07/4/2012 09:08: The really worrying point in this paper is that were now heating up the planet about 50,000 times faster than the slow warming trend 60 million years ago ______ Really? So, presumably, you can identify the fully comprehensive data ie covering the whole of the globe, not just the conveniently located areas that provides the actual 30 year moving average for global temperatures starting from 70 million years ago to the present time and demonstrates that the global average temperature is currently increasing at 50,000 times faster than 60 million years ago. I wont hold my breath.

The really worrying point in this paper is that were now heating up the planet about 50,000 times faster than the slow warming trend 60 million years ago which triggered off the PETM and other hyperthermals. longchamp le pliage black large Were racing towards extremely dangerous tipping points and we dont know exactly when were going to cross them this is not a reason to relax and carry on with business as usual, but should be a big red warning sign tha longchamp le pliage black large t we need to dramatically curtail greenhouse gas emissions before the warming gets completely out of our control.

Re: Richard, Wimborne, UK, 6/4/2012 9:54 ______ Ever heard of irony Richard? I suspect that Gordon Webster, Dundee, UK, 5/4/2012 20:28 was suggesting that scientists will soon follow up this latest theory, which includes the common sense assertion that changes in global temperatures are affected by changes in the Earths orbit, with a further theory that CO2 is the root cause of changes in the Earths orbit. Given the fact that the lunatic fringe already claim that the Sun would not cause water to evaporate longchamp le pliage black large if it were not for CO2 it is only a matter of time before Gordons prediction becomes another scientists fantasy sorry a peer reviewed scientific theory.

I will never believe another one of these stories again. We have been lyed to before about man caused global climate change and this may be no different. Next they will say it was caused by planet X. I know the earth has been colder and has been warmer, it is all natural. But, I fear how some will twist things in order to justify some new push to force us back to the dark ages. longchamp le pliage black large