Two years ago I posted this lecture by Professor John Christy.  Today I rediscovered it and on second viewing I felt it was still among the very best. In fact, after the recent Attenborough programme
this lecture is the antidote. Christy ticks all the boxes. He is highly qualified in the science; he has an impeccable record of honesty and integrity, and he uses simple evidence to put his arguments across with a good speaking style. This video is so good that I will add it to the must see material on this blog.