Biodiversity is the grand diversity of life on Earth and all the interconnections that support these myriad forms of life. 

Biodiversity is Important Because . . .

Biodiversity Threats . . .

How do Scientists Define Biodiversity? . .

Bibliography . . .

Today, scientists estimate that there are between 15 and 100 million species throughout the world. (The larger figure accounts for the unexplored diversity of microscopic life forms.)

This astonishing diversity supports our own existence, by giving us food, fuel, medicines and other products we need on a daily basis.  Biodiversity also helps us by providing "nature services," such as the forests that help clean our air, or the wetlands that clean our water and control floods.

But biodiversity, along with the benefits and services it provides, is diminishing. The rate of extinction today is vastly greater than at any time since the evolution of humans.

• In the US alone, nearly 4,500 species are threatened with extinction.

• As many as 500 plant and animal species have disappeared forever since people first arrived in North America.

Have you ever wondered why the California state flag features a grizzly bear?  Just 150 years ago, San Francisco Bay supported not just grizzlies, but salmon, pronghorn antelope, and cougar, too.  At that time, elk browsed in the forests of Pennsylvania.  Imagine what used to live in your backyard--do you know what lives there now?

We're not only losing species, we're also losing entire ecosystems: 

• 27 endangered ecosystems--such as the long leaf pine forests of the Southeast--have lost more than 98% of the area they occupied when the Pilgrims landed.

• 50% of the US no longer supports its original vegetation.

• In the Great Plains, 99% of the original prairies are gone.

• Throughout the US, we destroy 100,000 acres of wetlands each year.