Extinction and Biodiversity

In this lesson we explore what happens when species disappear forever, the causes of extinction, the importance of biodiversity, and the methods used to conserve it.

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What Is Extinction?

Extinction occurs when there are no living individuals of a species remaining anywhere on Earth. The species is gone permanently — it cannot come back.

Extinction is a natural part of life's history. Over 99% of all species that have ever lived on Earth are now extinct. However, the current rate of extinction is estimated to be 100 to 1,000 times higher than the natural background rate, largely due to human activity.

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Causes of Extinction

Species can become extinct for many reasons, often a combination of several factors:

1. Environmental Change

Change	Effect
Climate change	Habitats become too hot, cold, wet or dry for a species to survive
Sea level change	Coastal and island habitats are flooded or exposed
Habitat destruction	Forests cleared, wetlands drained, grasslands converted to farmland

2. New Predators