Re: [asa] Martian ice caps

From: George L. Murphygmurphy@raex.com <Murphygmurphy@raex.com>
Date: Tue Sep 11 2007 - 12:15:15 EDT

Since this topic is heating up (!) on the list I'll respond before I intended to - which was when I get home & can check some of my old astronomy teaching resources.  Briefly, a significant part pf Mars' icecaps is dry ice (CO2) rather than the water variety.  Sublimation of the CO2 of course will contribute to the greenhouse effect on the planet.  As Pim notes, there is significant seasonal growth & decline of the icecaps:  If I remember rightly, one of them has sometimes disappeared completely in that hemisphere's summer.  Seasonal effects on Mars are exacerbated in comparison with earth because of the fact that, while the inclination of Mar's axis is about the same as earth's, its orbital eccentricity is significantly greater (roughly 1/11 in comparison with 1/60).

So briefly, care is needed in comparing the 2 planets.  While Burgy's friend may be a good geologist, he/she may not be a knowledgeable areologist.

Shalom,

George

> > > Yes there are some excellent rebuttals to the ice caps on Mars and > the fluctuations in the sun's out and I will send them to you later. > The sun has been studied in quite some depth, as it is a likely > candidate to explain heating/cooling, however the studies have failed > to show a significant link between solar output and the warming trend. > In addition to the negative evidence for a solar cause, science also > has done excellent job at showing how the recent warming trend is > caused by a significant human component. > > While global warming deniers go to quite some extremes to 'disprove' > the obvious, the science supporting human causes global warming is > well established. All they can do is whine about a miniscule > temperature adjustment error caused by using the wrong dataset. > > As to Mars, the melting of the polar icecaps is indeed caused by solar > output, not that the sun is warming up but rather the planet. It's > called seasons. > > http://science.nasa.gov/headlines/y2003/07aug_southpole.htm > > > > > On 9/11/07, Carol or John Burgeson wrote: > > My geologist-clergy friend dismissed human influence on global warming to > > us yesterday as problematic and probably not factual on the argument that > > as earth's ice caps melt so are those of Mars -- fluctuations in the > > sun's output probably responsible. > > > > Is there a rebuttal to this? > > > > Burgy > > > > To unsubscribe, send a message to majordomo@calvin.edu with > > "unsubscribe asa" (no quotes) as the body of the message. > > > > To unsubscribe, send a message to majordomo@calvin.edu with > "unsubscribe asa" (no quotes) as the body of the message. >

George L. Murphy
To unsubscribe, send a message to majordomo@calvin.edu with "unsubscribe asa" (no quotes) as the body of the message. Received on Tue Sep 11 12:15:55 2007