A wet Mars but was it cold or warm?


The debate now is not that Mars has water; it has oceans of it frozen
under a thin layer of Martian dust, as the Phoenix Lander has shown.

Nor is it an issue that Mars has liquid water and once had LOTS of liquid
water.

The debate is, was Mars warm, or was it very cold.(1) Sadly, here is
where it gets political, for we are talking about CO2 and climate change.

I hate it when political hacks put on lab coats and pose as scientist.

The claim is, a slurry of chemicals lowered the freezing point of water,
much like salt lowers the freezing point of water. The obvious answer,
however, is that Mars was warmer, liquid water existed, and the water
vapor pressure put a lot more water vapor into the atmosphere and that
caused the warming. This would highlight that the large CO2 atmosphere of
Mars didn't cause the warming and that water vapor is the larger
greenhouse gas.

Mars today is thus like the "frozen earth" theory(2). Basically, this
theory is that the earth once had such a large ice age that the oceans
froze and water vapor was lost from the atmosphere. Without the water
vapor, earth got colder.


(1) http://www.reuters.com/article/scienceNews/idUSTRE54J5E220090520
(2) http://www.livescience.com/environment/070506_snowball_earth.html
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