Mystery mechanism drove global warming 55 million years ago

Jul 13, 2009
Close up of a melting glacier. A runaway spurt of global warming 55 million years ago turned Earth into a hothouse but how this happened remains worryingly unclear, scientists said on Monday.

A runaway spurt of global warming 55 million years ago turned Earth into a hothouse but how this happened remains worryingly unclear, scientists said on Monday.

Previous research into this period, called the Palaeocene-Eocene Thermal Maximum, or PETM, estimates the planet's surface temperature blasted upwards by between five and nine degrees Celsius (nine and 16.2 degrees Fahrenheit) in just a few thousand years.

The warmed to 23 C (73 F), or about the temperature of a lukewarm bath.

How PETM happened is unclear but climatologists are eager to find out, as this could shed light on aspects of today.

What seems clear is that a huge amount of heat-trapping "greenhouse" gases -- natural, as opposed to man-made -- were disgorged in a very short time.

The theorised sources include and the sudden release of methane hydrates in the ocean.

A trio of Earth scientists, led by Richard Zeebe of the University of Hawaii, try to account for the carbon that was spewed out during PETM.

They believe that levels of (CO2) rose by 70 percent during PETM's main phase to reach 1,700 parts per million (ppm), attaining a concentration of between four and five times that of today.

But all this CO2 can only account for between one and 3.5 C (1.8-6.3 F) of PETM's warming if the models for climate sensitivity are right, the team found.

There must have been some other factor that stoked temperatures higher.

Even though there are big differences between Earth's geology and ice cover then and now, the findings are relevant as they highlight the risk of hidden mechanisms that add dramatically to warming, says the paper.

Some of these so-called "positive feedbacks" are already known.

For instance, when a patch of melts, this exposes the uncovered sea to sunlight, depriving it of a bright, reflective layer.

That causes the sea to warm, which leads to the loss of more ice, which in turn helps the sea to warm, and so on.

But these "feedbacks" are poorly understood and some scientists believe there could be others still to be identified.

"Our results imply a fundamental gap in our understanding about the amplitude of global warming associated with large and abrupt climate perturbations," warns Zeebe's team.

"This gap needs to be filled to confidently predict future climate change."

After the big warm-up, the planet eventually cooled around 100,000 years later, but not before there had been a mass extinction, paving the way to the biodiversity that is familiar to us today.

Man-made global warming, driven mainly by the burning of oil, gas and coal, has amounted to around 0.8 C (1.12 F) over the past century.

Last week in L'Aquila, Italy, the Group of Eight (G8) industrialised countries and other economies that together account for 80 percent of greenhouse-gas emissions pledged to try to limit overall warming to 2 C (3.6 F) over pre-industrial times.

(c) 2009 AFP

Explore further: Synchronization of North Atlantic, North Pacific preceded abrupt warming, end of ice age

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User comments : 24

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defunctdiety
3.3 / 5 (7) Jul 13, 2009
pledged to try to limit overall warming to 2 C


::facepalm::
patnclaire
2.7 / 5 (12) Jul 13, 2009
The Inconvenient Truth is that people caused it then just like now. What?

Okay, then Java men caused it. What?

Chimpanzees playing with fire caused it. What?

Okay, then Lemurs caused it because of lighting torches to see in the night. What?
Okay, my bottom line...lets blame it on Mother Nature. We all know that it is not nice to fool with Mother Nature but who cares?

Flip Wilson says to blame it on Satan ...the devil made him do everything else!

Ockham's Razor says People did it ... so maybe A Sound of Thunder - kind of people?



What this finding should help with is the notion that our climate theory is incomplete, hence our climate models are incomplete, hence our data is incomplete, ergo our conclusions are incomplete. It may not be Politically Correct but it seems that there still may be room for skepticism. Was not it Carl Sagan who said that Extraordinary claims require extraordinary evidence? or was it someone else who said it?

mysticshakra
1.5 / 5 (8) Jul 13, 2009
If the Arctic was 73 degrees then the Arctic was obviously not in the same position on the planet that it currently resides and was much further south.

Since we know that Antarctica had no ice at one point (see the Piri Reis map and others like it) it shows that the continents are subject to some other mechanism than just plate tectonics.

The crustal shift/displacement model provides one possible answer.
Velanarris
3.4 / 5 (5) Jul 13, 2009
What this finding should help with is the notion that our climate theory is incomplete, hence our climate models are incomplete, hence our data is incomplete, ergo our conclusions are incomplete. It may not be Politically Correct but it seems that there still may be room for skepticism. Was not it Carl Sagan who said that Extraordinary claims require extraordinary evidence? or was it someone else who said it?
Correct, it was Sagan.

One would only hope that research like this will allow us to continue to refine our models to a point of congruence with our observations.

Especially given as the potential for warming due to CO2 is so low and grossly exaggerated.
If the Arctic was 73 degrees then the Arctic was obviously not in the same position on the planet that it currently resides and was much further south.
Wrong. The temperature of the poles was not always as cold as it is now.
di0nysus
1.5 / 5 (2) Jul 13, 2009
Why doesn't anyone ever seem to consider the Earths magnetic field when talking about climatology? I just dont understand how they can ignore it, it seems so basic.
Doug_Huffman
1 / 5 (1) Jul 13, 2009
And what is the connection, please, between a fractional Gauss strength surface magnetic field?
Shootist
2.3 / 5 (6) Jul 13, 2009
"For instance, when a patch of Arctic sea ice melts, this exposes the uncovered sea to sunlight, depriving it of a bright, reflective layer.

That causes the sea to warm, which leads to the loss of more ice, which in turn helps the sea to warm, and so on."

This causes evaporation to increase, which increases cloud cover, lowering temperatures and reflecting more sunlight back into space, while also increasing snowfall at higher latitudes, thus increasing ice and snow cover . . . feedback mechanisms indeed.



di0nysus
4 / 5 (1) Jul 13, 2009
And what is the connection, please, between a fractional Gauss strength surface magnetic field?


you mean aside from the fact that it changes its polarity on average every 200,000 years on average. And during the cycle changes the earth is completely stripped of its defense from the sun? We are undergoing a flip as we speak today as well, the field is getting weaker and weaker.
steelfire2
5 / 5 (1) Jul 13, 2009
Finally, Physorg displays an argument from the other side!

According to the article the globe was warmer 55 million years ago. The most recent ice age was about 20,000 years ago, so doesn't anyone consider that this might be more natural than man-made?
jyro
2 / 5 (4) Jul 13, 2009
Gee, news flash, we don't understand climate change yet we think it can be controlled by what we do? Spend resources to adapt to climate change, not trying to control it.
thermodynamics
3 / 5 (4) Jul 13, 2009
Since this paper does not address the subject, I will bring up Milankovitch Theory. As far as I know our GCMs do not take Milankovitch Theory into account and that means that the most potent driver for temperature (the position of the earth with respect to the sun) is not taken into consideration. If this article said they did take it into consideration I would be more surprised. Since they don't seem to mention it, I would expect that to be the basis of the discrepancy.
SDMike
4 / 5 (2) Jul 13, 2009
Republicans are apparently older than we thought.
BobArmstrong
4 / 5 (4) Jul 14, 2009
So perhaps 9c higher mean temperature ? About 3% increase on our approximately 300k . Since the Stefan-Boltzmann Law shows objects in our orbit are about 1/21 the surface temperature of the sun , why is it inconceivable that the sun for one reason or another went up about 270c on its approximately 6000k ?
Doug_Huffman
2.5 / 5 (2) Jul 14, 2009
"And during the cycle changes the earth is completely stripped of its defense from the sun?" Completely?

NO. Magnetic field shields only charged particles. Photons still get through.

What is the connection between climatology and a fractional Gauss field?
lengould100
not rated yet Jul 14, 2009
... As far as I know our GCMs do not take Milankovitch Theory into account ...
Whaaaaaaaat?
SDMike
5 / 5 (2) Jul 14, 2009
Milanovitch Theory - http://www.empori...eory.htm
GMC - Global Climate Models
di0nysus
1 / 5 (1) Jul 14, 2009

NO. Magnetic field shields only charged particles. Photons still get through.

What is the connection between climatology and a fractional Gauss field?


who said anything about photons?

maybe you should look at this detailed source:
http://www.appins...ield.htm

as well as countless others that cn be found quite easily, before you completely dismiss the idea altogether.
Velanarris
1 / 5 (1) Jul 14, 2009








who said anything about photons?







maybe you should look at this detailed source:







http://www.appins...ield.htm







as well as countless others that cn be found quite easily, before you completely dismiss the idea altogether.


I don't find the relevance here. These magnetic pole shifts happen often and spontaneously.

It appears you're trying to link Earth's local magnetic field to climate variation, however, Earth's magnetic field flux is driven by the magnetic field interactions with the sun and other local celestial bodies. Not the other way around. If anything you're jsut furthering the hypothesis that terrestrial climate is driven by magnetic fluxuation in the sun based on Earth's relationship to the Sun and the dynamics of the Milankovich theory.

... As far as I know our GCMs do not take Milankovitch Theory into account ...
Whaaaaaaaat?

He's correct. They also don't take into account current findings that raindrop fall faster than terminal velocity or one of many other thousands of possible relationships to climate variability.

dachpyarvile
1.7 / 5 (3) Jul 14, 2009
... As far as I know our GCMs do not take Milankovitch Theory into account ...
Whaaaaaaaat?


Come off it, len. We already know you don't understand the science. I mean, you could not even figure out by the science how using ethanol instead of straight gasoline could reduce CO2 emissions... :)
PPihkala
3.7 / 5 (3) Jul 14, 2009
One part of uncertainty is how are permafrost buried CO2 and methane deposits going to force the climate after they are freed into air when (not if) the permafrost will melt. I hope we can delay that event, since it has potential to make current human caused temperature rise seem very mild.
SDMike
3.7 / 5 (3) Jul 14, 2009
Hum, links to NASA where data supporting Milanovitch Theory WAS located now return a 404 error. Politics over science? Obama silencing GWT dissenters? Next they'll be burning books.
mysticshakra
1 / 5 (7) Jul 14, 2009
One of these days it will finally be admitted that there are no ice ages. The idea is based on a lot of assumptions and the evidence has other interpretations. It makes no sense to say the Earth suddenly started to periodically cool and thaw when there is no mechanism to achieve this besides the sun's energy output (which does not change).
Koen
not rated yet Jul 15, 2009
What is cause and what is effect? Changes in atmospheric content because of global warming, or vice verse? The sun is most influential on global temperature? Solar radiation fluctuations and solar wind fluctuations anyone?
defunctdiety
5 / 5 (5) Jul 15, 2009
One of these days it will finally be admitted that there are no ice ages. The idea is based on a lot of assumptions and the evidence has other interpretations. It makes no sense to say the Earth suddenly started to periodically cool and thaw when there is no mechanism to achieve this besides the sun's energy output (which does not change).


Yeah, there's certainly no indisputable evidence that glaciers at one time extended south into the northern parts of the US... certainly no glacial till beneath top soil and thousands of lakes carved into bedrock or anything like that, anything could have done that.

And there's certainly no planetary and orbital ocillation mechanisms that would change the angle and energy with which the suns rays hit the earth thereby drastically affecting the amount of energy reaching certain given latitudes...

And there's most certainly no runaway albedo affect possible, and never have there been volcanic eruptions or cometary impacts that sent reflective particulate matter miles up into the atmosphere that would take decades to settle out, all the time reflecting significant portions of the suns energy, cooling the planet.

No... NO!! It makes no sense at all!

Oh, and let's not forget the scientific fact that the sun does have cycles and events which affect it's energy output... fluctuations which are insignificant to it's own measure and surely they are just as insignificant to any bodies around it which only recieve tiny portions of that total energy... ... le sigh.