<P> Global warming is also considered to be a major potential threat to global biodiversity in the future . For example, coral reefs - which are biodiversity hotspots - will be lost within the century if global warming continues at the current trend . </P> <P> Climate change has seen many claims about potential to affect biodiversity but evidence supporting the statement is tenuous . Increasing atmospheric carbon dioxide certainly affects plant morphology and is acidifying oceans, and temperature affects species ranges, phenology, and weather, but the major impacts that have been predicted are still just potential impacts . We have not documented major extinctions yet, even as climate change drastically alters the biology of many species . </P> <P> In 2004, an international collaborative study on four continents estimated that 10 percent of species would become extinct by 2050 because of global warming . "We need to limit climate change or we wind up with a lot of species in trouble, possibly extinct," said Dr. Lee Hannah, a co-author of the paper and chief climate change biologist at the Center for Applied Biodiversity Science at Conservation International . </P> <P> A recent study predicts that up to 35% of the world terrestrial carnivores and ungulates will be at higher risk of extinction by 2050 because of the joint effects of predicted climate and land - use change under business - as - usual human development scenarios . </P>

When is an area regarded as having a high biodiversity