How much nature is enough?

A growing number of scientists now say that 50 percent of any given land or water ecosystem needs to be protected to maintain biodiversity and ecosystem services.

Many scientific assessments over the past 20 years have demonstrated that nature needs at least half of a given ecoregion to be protected, and interconnected with other such areas, in order to maintain its full range of life supporting ecological and evolutionary processes, the long-term survival of the species that live there, and and to ensure the system’s resilience in the face of environmental change.

A protected area is defined by the IUCN as a “clearly defined geographical space, recognised, dedicated and managed, through legal or other effective means, to achieve the long term conservation of nature with associated ecosystem services and cultural values.” There are various categories based on how much human use is allowed, but they are all managed primarily to preserve biodiversity.

Some nations are closer than others to achieving this ambitious but vitally necessary target. According to the World Database on Protected Areas, Venezuela currently has 53 percent of its territory protected. Costa Rica has 21 percent. Worldwide, 12.7 percent of the land surface of the planet excluding Antartica is protected.

The U.S. is distinctly average in this department. About 13 percent of the U.S. is protected under the IUCN definition, according to the U.S. Geological Survey. When Alaska and Hawaii are excluded, this figure drops to a pitiful seven percent.

There is also considerable variation among individual states. Alaska leads all with 45 percent of its territory protected. California has 24 percent, New Jersey has 18.

Only six percent of New Mexico is protected. When you consider that New Mexico is the fifth largest state and ranked fourth in overall biodiversity, the need to protect more of the state is clear.

For more information go to Nature Needs Half.