The global warming on Mars would support your claim that it is the Sun.
http://www.space.com/scienceastronomy/solarsystem/mars_snow_011206-1.html
http://www.space.com/scienceastronomy/mars_ice-age_031208.html
They've found that our southern ice cap is growing. Ignore the hysterical conclusion that they've drawn from it or do what I do & laugh. I went to school in the 60's & 70's. Back then, the doom & gloom hysteria was all about a coming ice age. Course, all of that is now ancient history.
http://www.palmbeachpost.com/news/content/world/epaper/2005/05/20/a17a_icecap_0520.html
Still, remember back to what they taught you when you were a child about the Earth's seasonal climate change. Did they tell you about tilt variations & wobbles, not to mention orbital oddities?
http://www.livescience.com/forcesofnature/050330_earth_tilt.html