text: Who knew? However, a casual question back in 2000, from a colleague while I was doing post-doctoral work at the Canadian Institute for Theoretical Physics at the University of Toronto, led to surprising revelations on climate change. My colleague, an astrophysicist, asked me how cosmic rays from supernovae could affect life on earth, which led me to explore this area of study. I found that the sun's variability as well as unrelated cosmic ray variations, explain a surprisingly large amount of the observed climate variations, from the 11-year solar cycle to geological time scales. In fact, models including the real effect of the sun also do a much better job in explaining 20th century global warming than those limited to the influence of human carbon dioxide emissions alone. h/t Kevin B