Global Biodiversity
The biodiversity of planet Earth is the total variability of life forms. Currently about 1.9 million species are known, but this is thought to be a significant underestimate of the total number of species.
Biodiversity has grown and shrunk in earth's past due to changes abiotic factors such as mass extinction, change in oxygen levels and sea levels. Climate change 299 million years ago was one such event. A cooling and drying resulted in catastrophic rainforest collapse and subsequently a great loss of diversity, especially of amphibians.
Current threats to global biodiversity include natural extinction, an event that occurs to species yearly, as well as human actions such as pollution. Invasion of non-native species can also have a negative effect on global biodiversity.
Read more about Global Biodiversity: Measuring Diversity, Known Species, Estimates of Total Number of Species
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