“I should have been clearer. Greenland always had glaciation, but the amount of non-iced over land during 1000-1200 enabled Vikings to settle it and grow food. The cooling that occurred afterward (The Maunder Minimum) forced the Vikings to flee. The point here is that there are dramatic changes in climate that happens on a sub-century scale, and to believe that the one happening now *has* to be man-made seems to gloss over historical parallels.”
Yes, not surprisingly there have been localized climate trends throughout history. However, the emphasis needs to be on ‘localized’. There is currently no evidence this, or the ensuing ‘little ice age’ was a global phenomenon.
Unfortunately, the warming we are observing currently *is* global in nature.
“Sunlight. There are two other minor factors that come to mind: geothermal energy, and energy absorbed and reemitted as infrared radiation by greenhouse gasses (yes, that’s what you guys are going to jump on).”
Wrong again! You missed a real biggie, surface area!
More dark water (versus white ice) mean more absorbed radiation and more warming. One of those nasty feed-forward mechanisms you will hear about more in the future.
