30 million reasons to go out and do something wild

We're surrounded by it. We depend upon it. We're losing it steadily and irreversibly. But we ignore it.

Biodiversity: the sum of life on Earth. Despite the fact that all of our lives, and the entire economy, depend critically on our wild living resources, we take them utterly for granted. But there are plenty of very compelling reasons that we shouldn't. About 30 million reasons, in fact, although most of them have yet to be discovered — just about one reason for every species on Earth.

It's Earth Day, a fitting time for an oped about biodiversity and just three of those reasons.

The first is present economic value. Realistic assessments of the economic value of biological resources almost never accompany policy decisions. But when estimates were made, the costs of biodiversity loss inevitably far outweighed the desired benefits. In total, the value of nature is more than the gross domestic product of the world ($18 trillion a year). When ecologists and economists teamed up to calculate the cost of replacing the myriad services that our living resources provide — "ecosystem services," as they are called — their rough estimate was $33 trillion a year. Academics debate this estimate, but all agree on the implication: We cannot fully replace our "natural capital."

Some find this dependency hard to believe, imagining a planet supported by farm-like "ecosystems by design." Unfortunately, that's wishful thinking. We are eons from understanding life well enough to do that: completely controlling an ecosystem would require understanding all of the interactions in that system, plus the interactions that shaped the evolution of the component species. Given how many species are involved, and the need to understand interactions between each individual species and between all sets of species (for example, the relationship between sea otters and kelp depends critically on the presence of sea urchins), the information required for complete understanding is unfathomable.

Our dependence on natural ecosystems is synonymous with our dependence on biodiversity. Healthy ecosystems are composed of many species keeping each other in check. An unhealthy system may have only a few misplaced pieces, either due to extinction or to "invaders" from elsewhere, unchecked by rivals, pests, and predators. Such minor perturbations can spell economic disaster and lead to cascades of extinctions. Take for example the invasion of zebra mussels to the Great Lakes, which has decimated the local fauna and has cost the economy billions of dollars.

Given the dire consequences of minor replacements and omissions of species, successful ecological manipulations are infeasible. We will continue to depend upon natural ecosystems and their species for climate control, air purification, water purification, soil maintenance, . . . and on and on. Biodiversity is worth the world to us.

The second reason is respect for the creatures themselves, a value that simply can't be properly summarized with monetary amounts. Every species is the result of the labors of billions of ancestors, struggling with every breath to ensure the survival of its lineage into perpetuity, fighting against the multitude of other creatures who strive to eat them, poison them, or crowd them out. I, for one, am in awe of those efforts. But the present human-caused rate of extinction is several thousand times higher than the natural "background" rate. Who are we to foreclose those lineages, once and for all? The fact that some species would elapse anyway does not justify human-induced extinction. The fact that people die naturally doesn't lessen the wrong of killing.

The third reason is the welfare of future human generations. We take wild nature for granted now, but once it is gone, our descendants will regret our myopia. It won't matter if they have far more powerful computers and far flashier video games: the fact that Americans are no happier today than 50 years ago attests that technological advances and economic wealth (beyond basic needs) don't buy societal happiness. Economists have shown that while individuals are happier with more frivolities than those around them, lasting social benefits are elusive: when everyone has more, no one gains. Meanwhile, some of our heirs will understand the wonder of the creatures we extinguish — just as we are in awe of dinosaurs, wooly mammoths and saber-toothed tigers — and they will resent us for our negligence. They will resent us or think, "What ignorant, shortsighted fools."

So this Earth Day, go out for a walk in nature. Plan a vacation, to a place where wild life abounds. Buy some books, enroll in a course, dust off your sneakers. Learn about nature, and experience it in all its glory. Appreciate and understand our fellow inhabitants of this spaceship Earth, and our place amongst them.

And then commit yourself to preventing this calamity that is extinction — for our sake, for the sake of the creatures themselves and for the good of the future.

Kai M. A. Chan is a graduate student in the EEB department. He is from Toronto.