How does global climate change affect biodiversity on earth?
Global climate change does not affect biodiversity, however rapid climate change has a negative impact on biodiversity.
Climate change creates winners and losers when you are talking about species. Species adapt or go extinct, and that is a normal thing. However, evolution is not something that occurs overnight. If the climate were to change rapidly which seems to be the case then many species may not have time to evolve.
So while certain species are able to take advantage of a warmer climate (sharks) due to an ability to easily adapt, a rapid change will mean a higher rate of extinction for those types of species that need to change quickly. Polar Bears will need to rapidly change their hunting habits if things continue, for example. If they cannot change quickly enough they could go extinct.