William Atkins
Sunday, 14 June 2009 21:09
Science -
Space
Page 2 of 3
The June 11, 2009 press release “
Caltech Scientists Predict Greater Longevity for Planets with Life,” from California Institute of Technology (CalTech),
“Earth maintains its surface temperatures through the greenhouse effect. Although the planet's greenhouse gases—chiefly water vapor, carbon dioxide, and methane-have become the villain in global warming scenarios, [key point]
they're crucial for a habitable world, because they act as an insulating blanket in the atmosphere that absorbs and radiates thermal radiation, keeping the surface comfortably warm.”
And,
“As the sun has matured over the past 4.5 billion years, it has become both brighter and hotter, increasing the amount of solar radiation received by Earth, along with surface temperatures. Earth has coped by reducing the amount of carbon dioxide in the atmosphere, thus reducing the warming effect. (Despite current concerns about rising carbon dioxide levels triggering detrimental climate change, the pressure of carbon dioxide in the atmosphere has dropped some 2,000-fold over the past 3.5 billion years; modern, man-made increases in atmospheric carbon dioxide offset a fraction of this overall decrease.)”
They state,
"… we're nearing the point where there's not enough carbon dioxide left to regulate temperatures following the same procedures." [CalTech]
However, the scientists say
another factor should be considered:
atmospheric pressure.
They suggest that atmospheric pressure could be substantially reduced if large amounts of molecular
nitrogen (which makes up over three-quarters of the atmosphere) disappear.
This lowering of our atmospheric pressure would better control surface temperatures and allow carbon dioxide to remain in the atmosphere.
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