Biodiversity "After Earth": Species Loss Is Real Threat, but What Would a Mass Extinction Event Look like? How Would We Be Affected? Biologist Joseph Levine Looks at a Future Where Less Biodiversity Has a Very Real Effect on Humans

Article excerpt

The movie After Earth (2013, directed by M. Night Shyamalan) takes place following a massive planetary extinction event and various other calamities that have forced humans to flee the planet. The film begins 1,000 years after humanity's departure. The remaining organisms have evolved to treat humanity as a hostile threat.

Parts of the film were shot on the grounds of the Organization for Tropical Studies (OTS) ( in Costa Rica, a center for research on biodiversity, tropical ecology, and climate change. The film's producers asked Joseph Levine, a biology educator, text-book author, and course director at OTS, to create an educational Web site,, to help students understand the film's backstory. I asked him about the science behind the After Earth scenario.

THE FUTURIST: There's evidence that we may be on the verge of a mass extinction event as large as the Permian extinction that took place millions of years ago. What would a mass extinction event actually look like if it occurred today?


Joseph Levine: When people hear "extinction" they usually think of endangered species such as white rhinos, or pandas. That's fine, because it's a tragedy when any species disappears. But a mass extinction is very different, and much more serious. During a mass extinction, environments change so radically, and so many species disappear, that entire ecosystems collapse. And that's important because healthy, functioning ecosystems provide very important services that the general public generally takes for granted.

For instance, terrestrial ecosystems do a fabulous job of catching and holding rainwater, purifying it, storing it, and providing us with clean fresh water. Ecosystems also provide habitats for pollinating organisms to live in. You've probably caught wind of the problems we're having with local pollinating insects. That's not pleasant to think about, because almost all plants that we rely on for food, other than grasses, are pollinated by bees or mosquitoes or bats or some other organism. Those pollinators need some place to live--and that's another service ecosystems provide.

The danger is that a bunch of economic drivers of global change are whittling away at the resilience and stability of the ecosystems on which we depend for those kinds of services. If those ecosystems collapse, the services they provide will disappear.

THE FUTURIST: When these biological systems start to collapse, it's not something that will show up on the news. But it actually affects the way consumers live in highly developed countries, and even in cities, right?

Levine: Yes. One great example involves the metropolitan area of New York City and its watershed north of the city in New York State. Talk about a futurist! Whoever was clever enough to set aside enough watershed back then to supply New York City now was an incredible genius. Thanks to that foresight, New York City has always had some of the best, most reliably clean drinking water of any major metropolitan area in the world.

That watershed area is under constant pressure for development of various kinds--industrial development, roads, residential development with septic systems, larger municipal sewage treatment facilities, and so on.

A while ago, there was a plan to open up larger tracts within that watershed to more intense development. But people were intelligent enough to study the likely effects of that kind of development on the ability of that watershed to provide New York City with the water it needs.

The city's planners and researchers discovered that development in the watershed area would produce all sorts of tax revenues and other economic benefits. But the loss of ecosystem services from that kind of development would require the city to invest trillions--not even billions, but trillions--of dollars into a whole new range of water treatment plants, because the water would no longer be as dependably clean as it has been. …