The Deadly Dozen Effects of Losing Nature

Mangroves (Photo: Diego M. Rossi/Getty)

My latest for TakePart:

There’s a tendency in our flat screen-fixated society to treat the preservation of nature and wildlife as a boutique issue. I mean “boutique” in the sense that it’s become a ladies-who-lunch sort of thing. Nice, but it doesn’t really matter.

Our own experience also reinforces the subliminal impression that destroying nature—or at least pushing it back away from civilized life—actually makes us healthier. Turning forests into fields has made it easier for us to get food, for instance, and building dams provides the electricity to power those flat screens, build products, and create jobs.

But a new study in Proceedings of the National Academy of Sciences argues that the continued loss of habitat is in fact increasingly a matter of life and death. Let’s skip the subtleties and go straight to a list of the study’s dozen deadly effects:

1. In Asia, Africa, and South America, those seemingly beneficial dams and irrigation projects have created new homes for the aquatic snail species that transmits schistosomiasis. It now afflicts more than 200 million people worldwide with symptoms including coughing, abdominal pain, diarrhea, fever and fatigue. The altered habitat also provides breeding places for mosquitoes and other disease-carrying organisms, increasing the incidence of malaria, filariasis, encephalitis, and other dreadful diseases.

2. Our increasing incursions into remote wilderness areas are bringing epidemic diseases out of the jungle and into our backyards. Roughly 75 percent of emerging diseases—think HIV, Ebola, West Nile virus, SARS, and the new coronavirus in the Middle East—spill over from the animal world.

3. When we reduce the variety of species living in an area, we make it more likely that new diseases will spill over to humans. The “dilution effect” theory suggests that when you have many species in a habitat, some of them will be ineffective, or even dead ends, at transmitting a particular disease pathogen. So they dilute the effect of the pathogen and keep it from building up and spilling over to humans. Studies have correlated reduced species diversity with increases in West Nile virus, Chagas disease, Lyme disease, and hantavirus.

4. When we destroy coastal mangrove swamps in Sri Lanka, or dune vegetation on the beach in New Jersey, we lose vital protection against deadly storms. In the Asian tsunami of 2004 one village in Sri Lanka that had cut down its mangrove swamps to create shrimp farms suffered 6,000 deaths. In a comparable Sri Lankan village that left its mangroves intact, only two people died.

5. By providing nursing grounds for young fish and for the prey species they will eventually eat, those mangrove swamps are responsible for about 80 percent of the global seafood catch. The continuing loss of seafood, as well as of land-based bushmeat, threatens a large segment of the human population with chronic iron and zinc deficiencies, meaning anemia, fatigue, and other symptoms.

6. Most of our drugs, including all antibiotics, originally came from the natural world. To cite three quick examples: ACE inhibitors, currently the most effective blood pressure medicine, were derived from the venom of South America’s deadly fer-de-lance snake. AZT, the first drug to turn AIDS from a death sentence to a treatable disease, was derived from an obscure Caribbean sponge discovered in the 1950s. Prialt, a potent pain medicine, comes from a Pacific cone snail that people used to value only because it has such a pretty shell.

7. When plant breeders need to make a drought-resistant strain of rice, or a wheat variety that doesn’t drop dead from disease, they often borrow traits from closely related plants in the natural world. The need for those traits is increasing because of climate change. But borrowing only works if there is a natural world left to borrow from.

8. When we lose habitat and species, we also lose essential pollinators for our crops, including insects, birds, and bats. Honeybees pollinate about a third of U.S. crops, and the recent drastic decrease in their population imperils a harvest worth more than the $15 billion a year. According to the study, pollinators are a key factor in producing about a third of the calories and micronutrients we depend on.

9. Clearing forests has led to reduced access to fuel for cooking, creating an extra burden for the women and girls in developing nations who generally do the wood gathering.

10. Loss of hillside forests means water tends to run off rather than soak in. That makes it harder to find water, for crops, sanitation, or safe drinking. And again, it’s generally the women who have to go farther and pump harder, then carry the water home by the bucketful.

11. More than 100,000 people have died so far in the civil war in Syria, which, it’s been argued, was set off as much by persistent drought as by bad government. On a much smaller scale, but closer to home, a heat wave last summer caused 82 known deaths across the United States and Canada. Climate disruption is likely to cause increasing human health impacts in the form of heat stress, air pollution, respiratory disease, and food and water shortages. The question of social justice runs through this discussion: We in the developed world tend to benefit in our relatively prosperous lives, while the poor and disenfranchised get stuck with the bill.

12. In our mobile, rootless society, it’s easy to forget what we have never had.  But losing habitat can mean losing an essential sense of place and of self, and that can lead to depression, emotional distress, and other psychological effects.

The authors of the new study, who come from Harvard University, the Wildlife Conservation Society, Conservation International, and other institutions, make one major recommendation. Up to now, our research into the natural world has been driven largely by scientific curiosity. Instead, scientists now need to think a lot harder about policy.

For instance, when Brazil eases restrictions on land use in the Amazon, researchers should be ready to project exactly how that will affect local malaria rates. When policymakers in Southeast Asia are debating the use of fire for land clearing, scientists should be able to explain the public health implications from air pollution in downwind areas of Indonesia, Singapore, and Malaysia.

These kinds of considerations may sound, as the editor at a prominent magazine recently told me, “unsexy.” Not cool. But the new study makes it clear that if we don’t start paying much closer attention to them, and to the state of the natural world, we are all in imminent danger of ending up dead.

And that would be the unsexiest thing of all.