Starship Asterisk*

1st, I don't think this should go to the cafe -for obvious reasons. :shock:

2nd, the race to find the cause(s) is definitely on. Just remember to beware of any findings that are published by scientists whose work is subject to the U.S. government. :wink:

I wonder if the changes in Earth's magnetic field might be a catalyst or cause?

There is at least one APOD on Mars' southern polar cap - [url=http://antwrp.gsfc.nasa.gov/apod/ap011213.html]13 December, 2001[/url].

Yes. Actually a few studies have looked at this and similar ideas. One shows an overall [url=http://www.newscientist.com/article.ns?id=dn1660]decrease[/url] in the amount of ice at the Martian poles between 1998 and 2002 (2 Martian years). However, we haven't been observing Mars long enough to really understand long-term trends. No precise measurements date back further than this.

Several feasible ideas have been proposed for non-human effects on the Earth's climate. The most focused on are orbital harmonics (mostly how the aphelion and perihelion coincide with summers and winters over time), variations in the solar output over 40,000-100,000 year cycles, and cosmic ray intensity affecting the formation of cloud cover.

I believe orbital harmonics studies are generally accepted to find too small of an effect.

Long term variations in solar output have been found to be theoretically capable of matching the long term cycles of climate change for both length and magnitude. A mechanism for these changes has also been supported through modelling.

Cosmic ray affects on cloud formation have been shown to be able to theoretically be capable of matching the timing and magnitude of climate change cycles, but I'm not sure if a mechanism has been proposed.

Also, if a solar cause is implicated, what does that say about the effect of man-made emissions, which have definitely increased? As I understand, some level of greenhouse gasses is necessary to explain the comfortable temperatures we currently enjoy. Perhaps greenhouse gasses play a declining role in global climate as concentrations increase.


Lastly, this should probably be in the Cafe.

Interesting thoughts, though I wonder with a system as complex as an entire planet and with a small sample size whether one could infer the sun is the cause if, say, the Mars cap were to be shown to be smaller.

Still, without the influence of life on Mars the system IS rather simpler...

-Noel

[img]http://mars.jpl.nasa.gov/gallery/polaricecaps/browse/br_PIA02393.jpg[/img]

So here's my question:

Is there any data on the size of the polar ice cap today compared to, say, the Viking missions or other observable years?

My ultimate idea is to compare that of a planet that man has had practically NO impact on to that of our own planet.

Could it be said that if our polar ice caps are melting at a certain rate and Mars' was at a proportionate rate that the changes could NOT be explained by "man did it"... and perhaps it was due to the sun's activity as others have proposed?