Let's not forget global warming on Pluto.
http://www.space.com/scienceastronomy/pluto_warming_021009.html
The nut-jobs will just claim that Pluto is no longer a planet so it doesn't count...
"The increasing temperatures are more likely explained by two simple facts: Pluto's highly elliptical orbit significantly changes the planet's distance from the Sun during its long "year," which lasts 248 Earth years; and unlike most of the planets, Pluto's axis is nearly in line with the orbital plane, tipped 122 degrees. Earth's axis is tilted 23.5 degrees. Though Pluto was closest to the Sun in 1989, a warming trend 13 years later does not surprise David Tholen, a University of Hawaii astronomer involved in the discovery. "It takes time for materials to warm up and cool off, which is why the hottest part of the day on Earth is usually around 2 or 3 p.m. rather than local noon," Tholen said. "This warming trend on Pluto could easily last for another 13 years."
... So it's unrelated to either solar activity or the Earth's carbon cycle, the latter being a rather obvious conclusion.