I'm old enough to remember Global Cooling being touted as a big threat in the 1970's. The cooling was supposed to occur due to man made changes in the upper atmosphere. (Check wikipedia. I am not making this up.) Now popular reports of weather science have switched to Global Warming, the latest fad in weather. However, most of the current models do not predict into the future with any accuracy. I think the sun's energy output has much more to do with climate than atmospheric conditions. When I visited Exit Glacier, near Seward, Alaska, I noticed that the glacier has been receding since 1815. Park Service personnel recently discovered evidence of a buried forest dating back to at least 1170 AD near the current glacier’s edge. I don't think the cooling of the Little Ice Age between 1300 and 1870 had much to do with a switch to renewable energy. Basing predictions of weather trends over geologic time scales using the last 150 years of data is statistically ridiculous. Imposing costs on society based on Global Warming hysteria will only harm the poor, who benefit most from cheap energy.
http://www.eh-resources.org/timeline/timeline_lia.html Little Ice Age Article