Mystery mechanism drove global warming 55 million years ago
July 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 Arctic Ocean 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 global warming 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 volcanic activity 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 atmospheric carbon dioxide (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 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.
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
Mar 14, 2006 |
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::facepalm::
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?
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.
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.
Wrong. The temperature of the poles was not always as cold as it is now.
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.
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.
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?
NO. Magnetic field shields only charged particles. Photons still get through.
What is the connection between climatology and a fractional Gauss field?
GMC - Global Climate Models
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.
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.
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... :)
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.