Mystery mechanism drove global warming

[olddragon]

Mystery mechanism drove global warming 55 million years ago

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.

[Goldmoon]

All I can think of is the Galactic Plane... lol

Or interference from something alot larger.

Remember, there are planets out there that would bear creatures larger than our own earth.

[James Random]

It could very well have been The Mars Incident. We know that 65 Million years ago Mars was alot like Earth (in fact, Mars was MORE suitably for human development and habitation than Earth is) and that at some point a catastrophe cause the planet to become the lifeless rock we are today just beginning to explore (we've always had an unnatural fascination with this planet above all others. Why?).
It is possible that whatever fate befell Mars (the current thinking is a terrific asteroid impact) could have had environmental consequences on it's neighbours. In Earth's case, the trigger for Global Warming.

A rough preliminary theory (of my own) suggests that dust and ashes from Mars could have been propelled into space and then caught in Earth gravity. If the amounts of dust (billions and billions of tonnes of it) were every day for many years bombarding the atmosphere and burning up, this could have caused a heating of the atmosphere at an increment that served as the trigger for global warming. Dust and debris burning in the atmosphere all day every day over a long period of time might have had a heating-effect on the Earth. However this is just a loose theory.

[alpha]

some people talk about severe Gamma ray bursts. In particular from our Galaxy's core. We've had a few from distant Galaxies but nothing from our core.

One scientist says if we get a big one, that lasts for thousands of years it could effect the climate, on the warm side, for thousands of years.

And, funnily enough when the Sun is in a Maximum it and its surrounding Planets can fend off big energies, when its in a Minimum it can't and all of it's Planets can't fend of serious Space energy!

something DEFINITELY to be worried about

and something obvious!

[Traveler]

Even if we did work it out I doubt that we could do anything about it. Being able to make small machines is a long way from the ability to terraform a planet.

[alpha]

learning the ability to "work it out" as you say will be invaluable in the long term future for the human race i reckon.

based on when we FINALLY work out how to travel properly throughout the Universe we can estimate a Planet's long term sustainability based on it's past, present and future climate potential.

It's all Physics anyway, there's a mathematical formula in there somewhere to work out how, when and where the next ice age will come to THIS Planet! or any extinction level event for that matter.

.......another idea for my book. thanks Traveler, you made me think of the above instantly!

[Nasik]

Mystery mechanism drove global warming 55 million years ago


http://i246.photobucket.com/albums/g.../butcher-1.gif

Interesting article. In E. Science, which reviewed the study co-authored by Dr. Zeebe (now available online) it says that core samples show time and time again, you have a rise of CO2 and the temperature follows. It says that the study found during the PERM carbon dioxide levels rose to about double normal levels in a relatively short period of time, but that the planet warmed substantially more than what current models predict - the conclusion was that there is a feedback loop we don't fully understand the impact of.

In other words, Dr. Zeebe (if you review some of his other articles) isn't discounting that humans are depositing CO2 into the atmosphere nor does his current or previous findings contradict that such anthropogenic deposits are augmenting the warming of the planet - no, what he is saying is more of the "worse than the worse case scenario" and that the carbon content in the atmosphere passed a threshold that triggered a powerful feedback loop(s) - that we don't understand yet.

It ain't good news.