July 14, 2009

Earth’s Mysterious Prehistoric Warming

A huge amount of global warming transformed the Earth into a hothouse 55 million years ago, but the cause remains a mystery, scientists stated on Monday.

Prior research into the Paleocene-Eocene Thermal Maximum, or PETM, notes that the planet's surface temperature increased by between 9 and 16.2 degrees Fahrenheit in just several thousand years.

The Arctic Ocean's median temperature rose to 73 degrees, or the temperature of a lukewarm bath.

PETM's heat wave is enigmatic, but climatologists desperately want to find out the cause, in hopes that it will shed light on current global warming trends.

Although a lot of the scientific evidence is indistinct, what is clear is that large quantities of natural "greenhouse" gases were expelled in a short amount of time.

The theorized place of CO2 creation includes volcanoes and the release of methane hydrates into the ocean. Three Earth scientists, led by Richard Zeebe from the University of Hawaii, try to explain the source of the carbon that was emitted during the PETM.

They theorize that CO2 levels increased by 70% in PETM's main phase to arrive at 1,700 parts per million, creating a concentration of four and five times that of today.

However, all the CO2 only accounts for between 1.8-6.3 F of PETM's warming if the models are completely accurate, the team noted. There had to have been an additional factor that raised the temperatures.

Even though there are large distinctions between Earth's geology then and now, the study is important because it highlights the hazards of hidden things that can unknowingly add to global warming.

Several of these "positive feedbacks" are currently known. For example, when a piece of Arctic sea ice melts, it reveals the sea to sunlight, robbing it of its protective layer. That causes an increase in the sea's temperature, which causes more ice to melt.

However, a few of these "feedbacks" are not clearly understood and several scientists think that others still need 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," stated Zeebe's team. "This gap needs to be filled to confidently predict future climate change."

After the earth's warm-up, the planet gradually cooled down 100,000 years later, but still suffered a mass extinction, creating the biodiversity that is recognizable to us today.


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