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April 6, 2007 / D.F.Dufty

Global warming on mars

In 2005, NASA reported that its Mars Global Surveyor had detected three consecutive years of melting and shrinkage of the southern polar ice caps. This was interpreted by many as evidence of global warming on mars.
In response, National Geographic ran an article about Habibullo Abdussamatov, head of space research at St. Petersburg’s Pulkovo Astronomical Observatory in Russia. Abdussamatov is a global warming skeptic:

“Man-made greenhouse warming has made a small contribution to the warming seen on Earth in recent years, but it cannot compete with the increase in solar irradiance.”

As balance, they also interviewed other scientists who said that his views were well outside the mainstream consensus of climate scientists.
Realclimate.org ran an article disputing the conclusions, suggesting that a three-year local change was not enough data to infer global warming. The logic of skeptics went like this: if Mars is warming (and there is some – rather less compelling -evidence that Triton and Pluto are as well), then perhaps the solar system is warming due to solar fluctuations.
The story made the rounds of newspapers and blogs but was largely forgotten. It re-emerged this week with the publication in Nature of a paper on the Martian climate. The authors, Lori Fenton of the Carl Sagan Center as well as Paul Geissler (NASA) and Robert Haberle (US Geological Survey), report on simulation models that they developed of the Martian surface. Their conclusion is that the current warming on Mars is due to changes in wind patterns causing dust storms. These wind patterns, in turn, were caused by changes in the brightness of the surface of Mars, caused by deposits of bright dust. In short, it’s a cyclical phemonenon that’s unique to Mars.
Fenton told Space.com:

“A dust storm is kind of like a big party that picks up dust and tosses it everywhere,” said study leader Lori Fenton of the NASA Ames Research Center in California. “It takes forever to clean up after a party.”
Once the dust storm subsides, particles fall out of the atmosphere and are redistributed over a large portion of the planet. “You can almost think of a big dust storm as a resetting mechanism.”

If the researchers are right, then Martian “global warming” is due to dust storms, not solar output. So that would seem to take the wind out of the sails of warming skeptics. After all the skeptical argument went something like this:
1) Earth and Mars are both warming.
2) Ockam’s razor would suggest a common cause
3) this common cause is most likely due to the sun
4) therefore global warming, being due to the sun is
(a) out of our control, and
(b) nothing to worry about (since fluctuations tend to reverse).
But if the warming on Mars has nothing to do with the sun, then there are really no lessons in it for us Earthlings. Essentially, this weakens the solar fluctuation argument, and weakens the Martian global warming as a data point in the debate.
This study, it was hoped, would put to rest a key climate-skeptic talking point. However, judging by the response around the internet, it has not achieved this, at least in the public domain. The rhetorical power of another planet experiencing climate change has led to a chorus of skepticism about the reality of man-made global warming on earth.
The release of the study coincides with an editorial about overblown rhetoric from climate scientists in the Sydney Morning Herald:

The first thing that strikes you on reading the latest consensus report from the world’s climate scientists about the effect of global warming is that it is like the plot of an Armageddon movie.

and later…

The next thing that strikes you about the report is the high degree of uncertainty to which the authors readily confess. Climate change, the scientists write, “is taken to be due to both natural variability and human activities. The relative proportions are unknown unless otherwise stated”.

It is true that some activists for action on climate change sometimes overstate the case. Calm, reasoned argument may not grab headlines in the short term, but it is better in the long term. Hyperbole gets a lot of attention, but it can come back to bite you.
While Martian climate change causes storms here on Earth, it may be good news for our species down the road. In fact, it may eventually make the Martian environment a habitable place for humans to live. A NASA report in 2001 noted that Mars was too cold to support humans or many other Earth species. A suggestion was made that introducing greenhouse gases into the Martian atmosphere may induce sufficient warming for Earth-like life to be supported.
Of course, if Martian warming is merely part of the Martian long-term weather cycle, then we may just have to do it ourselves.

One Comment

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  1. Anonymous / Dec 7 2009 2:28 am

    And why did this dust storm occur? Seems to me something energized the atmosphere…

    Timothy Birdnow

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