Tapping reports no change in the sun's magnetic field so far this cycle and warns that if the sun remains quiet for another year or two, it may indicate a repeat of that period of drastic cooling of the Earth, bringing massive snowfall and severe weather to the Northern Hemisphere. (dotearth.blogs.nytimes.com)
Studies have shown that before this drastic cooling event, Earth's atmosphere contained 1,000 parts per million (ppm) of CO2 or more, and by the end of the transition, it was likely lower than 600 - 700 ppm. (sciencedaily.com)
But warming could also lead, paradoxically, to abrupt and drastic cooling («Global warming's evil twin»)-- a catastrophe that could threaten the end of civilization. (williamcalvin.com)