Over Half of Earth’s Wildlife Has Been Killed in the Past 40 Years

Fifty-two percent of the world's vertebrates — mammals, birds, reptiles, amphibians, and fish — were lost between 1970 and 2010 because humans are destroying habitats and consuming animals faster than they are able to reproduce, according to a report by the World Wildlife Fund (WWF).

Carbon dioxide emissions, agricultural pollution, and stress on water supplies, the group adds, are leading to potentially irreversible changes to the environment, driven primarily by demands for energy and consumer goods in rich, industrialized nations.

"The populations we measured are half the size of what they were 40 years ago. That's pretty astounding," Colby Loucks, senior director of conservation science at WWF, told VICE News. "When ripping apart nature you get holes. And when you rip things apart this much you're going to get some pretty big holes."

WWF tracked population trends in 10,380 groups of 3,038 vertebrate species. The 52 percent decline is steeper than in previous WWF reports on animal populations because the organization used a "better representation" of species. The report states there is no sign the trend will reverse.

Animals living in freshwater environments have been hit hardest — declining 76 percent. Marine and terrestrial populations fell 39 percent. The biggest declines occurred in South America and the Asia-Pacific region.

"What I thought was striking about the report was they did excellent and groundbreaking research to document the population trends of thousands of species," Kieran Suckling, executive director for the Center for Biological Diversity (CBD), told VICE News. "The results were very frightening."

Industrial and agricultural practices that pollute the atmosphere and oceans, as well as growing demands on freshwater supplies are unsustainable, says WWF, and could trigger catastrophic changes to ecosystems and the climate.

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WWF says that humans are emitting more carbon dioxide than the Earth's trees and oceans can absorb, putting the planet on track to exceed the 3.6 degree Fahrenheit rise in average global temperatures that some scientists have identified as a threshold for avoiding dangerous changes to the climate system.

While nitrogen-enriched fertilizers have helped boost agricultural production over the past 60 years, they also pollute rivers, lakes, and streams, states the report. Untreated wastewater in urban areas also disrupts aquatic ecosystems. High concentrations of nitrogen in waterways causes algae to bloom, which deprives rivers or lakes of oxygen and produces "dead zones," where no life can survive.

Agricultural production accounts for over 90 percent of the world's freshwater consumption and many countries are depleting supplies faster than they can be replenished. Areas of the US, China, and India are particularly vulnerable to water scarcity. Each is largely self-sufficient in agricultural production but prolonged drought could cut into each nation's crop yields.

"The challenge is how do we move high-, medium-, and low-income nations onto a sustainable development path," Loucks said. "I don't think our economy could function without the services ecosystems provide - that keep our planet alive and prosperous," he told VICE News. "To be prosperous we need healthy ecosystems."

Suckling sees cause for optimism in the passage of landmark environmental legislation in the US throughout the 1970s.

CBD is conducting parallel research to WWF into endangered species populations in the US. Suckling says his group has found an opposite trend to WWF.

"When put under the protection of federal laws," said Suckling, "species populations improved. But common species tend to decline in the absence of habitat and endangered species protections. Species that have been protected by federal law have, overall, improved since the 1970s."

"What that shows," he said, "is that when we put our mind to it and take action we can get strong population growth among endangered species."

Loucks told VICE News, however: "What were seeing is that high-income countries are experiencing economic growth at expense of low-income countries. Low-income countries bear the brunt of the problem."

Follow Robert S. Eshelman on Twitter: @RobertSEshelman

Image via Flickr