Today, biodiversity is exposed to a lot of fatal threats: destruction of habitat, pollution, over-exploitation and climate change. According to Ray Harris (2002), building cities on farmland leads the ruin of territory, for example those in California. He pointed out that nearly half of key major agricultural land in California is filled with buildings. Pearce and Williams (2008) also argued that the large areas of Brazilian rainforest have been wiped out, and this clearing forest for timber is one of the factors of the destruction of habitat.
Biodiversity is also exposed to pollution. Pearce and Williams further stated that oil spilled in the sea kills animals and plants (2008). For instance, in France, Amoco Cadiz leaked about 0.25 million tons of crude oil in 1978, and it was the key damage to environment. Moreover, Chen et al conducted the research and discovered that the vulture population in India decreased due to over consuming insect killers from grass (2009). It showed using pesticides on farmland is harmful to ecosystem.
Over-exploitation and climate change are also considered as hazards to biodiversity. In relation to over-exploitation, it can eliminate species, a position supported by Chen et al. They examined the research and observed that Cod died out Newfoundland in Canada in 20th century due to over-fishing (2009). Regarding climate change, higher temperatures can kill animal and plant species (Alvin, 2010). Hibernating animals may wake early due to the warm weather, and they are usually suffering from no food available.