Is there evidence supporting claims of mass extinction and world wide famine from rapid climate change?
Severe rapid climate change can cause mass extinctions such as the result of the impact that caused the K-T extinction (its about 65% not 25), or the Permian mass extinction about 250 million years ago (95% loss of biodiversity, much more severe than the K-T one), this was caused by the break up of Pangea which would have dramatically increased volcanic activity. Or the Eocene epoch about 35 million years ago, about 20-25% of the biodiversity, this was caused by Antarctica drifting into its current position and freezing over, this caused massive disruption of ocean currents, which affected the environment on land i.e once rainforests turn to grasslands, grasslands turn to desert etc. I think that a 3-4 degree change would cause some loss of biodiversity, but I think that that projection is pure fantasy, these events probably caused an 5-6 degree change and they were truly apocalypic, for example the meteor impact at the K-T boundary, that released the energy of 10 billion nuclear bombs
