Here is an even better reason to believe "Global Warming" may be a solar event rather than a man made event:
"New MGS Mars Orbiter Camera (MOC) images have provided a startling observation: The residual martian south polar cap is changing. The fact that it is changing suggests that Mars may have major, global climate changes that are occurring on the same time scales as Earth's most recent climate shifts, including the last Ice Age.
MOC images of the south polar cap taken in 1999 were compared with images of the same locations taken in 2001, and it was discovered that pits had enlarged, mesas had shrunk, and small buttes had vanished. In all, the scarps that enclose the pits and bound the mesas and buttes retreated about 3 meters (3.3 yards) in 1 martian year (687 Earth days). This rapid retreat of polar scarps can only occur if the ice is frozen carbon dioxide (also known as "dry ice"). Retreat of scarps made of water ice is much slower and would not have been measurable from one martian year to the next."
The full report and pictures may be found here:
http://mars.jpl.nasa.gov/mgs/msss/camera/images/CO2_Science_rel/
Yup. Heard Rush talking about it some weeks ag, and it's become my stock answer when the question comes up:
If you think our civilization is responsible for global warming, how do you explain that Martian ice caps are melting? How can we, on Earth, cause global warming on Mars? We can't. And we can't cause it here, either.