Global Warming Mostly Confirmed - On Mars

dinotrac writes "A just-completed 23 month study, carried out over the course of a Martian year, found that the Martian polar ice caps are rapidly eroding, sending large amounts of the greenhouse gas carbon dioxide into the Martian atmosphere. If this pattern continues over time, Mars could go from a planet whose winters are cold enough for dry-ice snow to having a shirt sleeve atmosphere. Humans would still have to provide for oxygen, but plants could go naked. I wonder if this means tougher emission controls on the next Martian rover?"

Comments

Influence of solar activity

[p4k]

This would seem to support the theory that variations in solar activity are very significant in determining climate. It is known that the output of the sun is slightly higher during periods of high solar activity. We are just about at the peak of a solar cycle at the present, and the last few cycles have been strong, and it would appear that this is affecting the climate on both planets.

This graph from this report shows a striking correlation between the length of solar cycles and mean temperature over the last hundred years (interesting that the length of the cycle should give the best correlation - the authors suggest the shorter solar cycles correspond to higher solar output).

Also, there is considerable historical evidence that the current change in climate is really pretty small beer compared to what has happened in the past:

"The Norwegian farmer Folke Vilgerdson made the first attempt to settle in Iceland in about 865 AD... He lost his cattle in a severe winter and disappointed went back to Norway after having seen a fjord filled up by sea ice. Therefore he called the country Iceland. Only a few years later, in 874, Ingolf Arnason succeeded. He was followed by many others, and settlement was completed in 930 AD... In 982, Erik the Red discovered new land West of Iceland. He called it Greenland; according to the Greenlander Saga this was only to persuade people to follow him... But the O(18) curve suggests that the name described a reality... So the drastic climatic change [warming] late in the ninth century may be part of the reason why Iceland and Greenland did not get the opposite names." (Dansgaard: Palaeo-Climatic Studies on Ice Cores, in Oeschger, Messerli and Svilar, 1980).

Here is another account, also suggesting that Greenland had a suprisingly comfortable climate at the time.

Most of the atmosphere went down, not up.

[Spamalamadingdong]

Photodissociation of water may have released a lot of Martian hydrogen to leak away (the very high proportion of deuterium in Martian water compared to Earth's strongly argues for this), but the oxygen and whatnot are too heavy for much to escape that way. The only place for them to have gone is down.

This means that the oxygen, nitrogen and carbon are probably in the soil. This would explain why Mars is so red (all that oxidized iron) and why the atmosphere is so rarefied (most of the gases are tied up as permafrost, adsorbed gas or chemical compounds like nitrates). It also means that the right kind of change can release them and make them into a thick atmosphere again.

Bob Zubrin of the Mars Society has written that we could start what would probably be a substantial greenhouse effect on Mars with only a few million tons of greenhouse gases (such as sulfur hexafluoride and methane) per year. This is the output of one large-scale industrial plant. Once you start heating the soil the adsorbed gases come out and the permafrost melts, leading to more warming and more gas release. Once you've got 200 millibars of atmosphere you can walk around outside with nothing fancier than a heavy parka and an oxygen mask. That's not bad for a planet that's currently an iceball with 7 millibars of fire-extinguisher contents for "air".

Cool Animations of the Melting Ice Caps

[EccentricAnomaly]

Here are some "cool" animations where you can see the ice caps melting. Also, here's a JPL press release which is a little more level headed than the news coverage.