The ESA: Taking Noah’s Ark Into a Brave New World


The Endangered Species Act (ESA), created in 1973 to prevent extinction, is one of the most powerful environmental laws on Earth. The U.S. federal government designed it to function like Noah’s Ark: you bring aboard species that risk extinction, a process called listing, and then use the best science to save them.

In the past 42 years we’ve put over 2,000 species of animals and plants on the ESA ark; only 30 have succumbed to extinction. However, some experts protest defining ESA success in terms of species still on the list rather than by the number of species that have recovered. And some argue that today this powerful statute is failing us, because we live in a far more complicated world than in 1973.

The bald eagle, an ESA success story. Photo by Cristina Eisenberg,

Back then, we hadn’t discovered that all species are connected via food web relationships called trophic cascades. We didn’t know that some, called keystone species, can touch everything in a food web: that their presence can cause biodiversity and ecological productivity to soar, making ecosystems more resilient. And we certainly didn’t know that by heating up the planet, human activities had provoked a crisis that would become known as the sixth extinction.

We’re living in a brave new world unimaginable in 1973. Additionally, we now know that preventing extinction isn’t just about preserving individual species so they can propagate and survive. It’s about preserving these species’ ecological roles and relationships with entire ecosystems.

The ESA’s biodiversity clause mandates that we “. . . provide a means whereby the ecosystems upon which endangered species and threatened species depend may be conserved.” This clause opens the door to fully considering keystone species effects when setting recovery goals.

Wolves hunting in Yellowstone. National Park Service photo.

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