MASS EXTINCTION A mass extinction is a global, catastrophic event with more than 65% of
all species becoming extinct. There have been 5
mass extinctions over the past 500 million years and in each case there was a huge loss of biodiversity.
Both environmental and biological factors have led to
mass extinctions. The suggested causes include global cooling, falling sea levels, predation and competition.
Our planet is now in the midst of its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past
half-billion years.
