Humans killed nearly two-thirds of the world's wildlife over 50 years, report says

By the end of the decade, global wildlife populations could be just one-third of what they were 50 years ago because of humans, scientists warned in a World Wildlife Fund report released Thursday.

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According to the Living Planet Report 2016, populations of fish, birds, mammals, amphibians and reptiles declined 58 percent between 1970 and 2012, the most recent year for which data is available. The report tracks more than 14,000 populations of more than 3,700 species.

"Wildlife is disappearing within our lifetimes at an unprecedented rate," said Marco Lambertini, director general of WWF International. "This is not just about the wonderful species we all love; biodiversity forms the foundation of healthy forests, rivers and oceans. Take away species, and these ecosystems will collapse along with the clean air, water, food and climate services that they provide us."

Wildlife populations have been hardest hit by the loss and degradation of their habitats due to unsustainable agriculture and logging and changes to freshwater systems, according to the WWF report. Currently, one-third of the planet's land area is covered in farmland and agriculture accounts for nearly 70 percent of our water use.

Other threats to wildlife include pollution, climate change, species overexploitation and the introduction of invasive species and disease.

Freshwater populations have been hardest hit, according to WWF, with populations falling a staggering 81 percent between 1970 and 2012, due mostly to habitat loss and degradation. The habitats are particularly difficult to protect, the nonprofit said, because they're affected by everything from pollution to dams and often cross administrative and political borders.

"Importantly however, these are declines, they are not yet extinctions – and this should be a wake-up call to marshal efforts to promote the recovery of these populations," said Ken Norris, director of science at the Zoological Society of London.

In its report, the WWF outlines a number of measures aimed at reforming the way humans interact with the planet in order to stymie wildlife losses. The nonprofit notes that global initiatives aimed at stopping global warming, such as the Paris climate deal, will help support wildlife growth.

"The world is reaching a consensus regarding the direction we must take," the report says. "Furthermore, we have never before had such an understanding of the scale of our impact on the planet, the way the key environmental systems interact or the way in which we can manage them."

Still, more work needs to be done to address environmental degradation, according to the report.

"We must create a new economic system that enhances and supports the natural capital upon which it relies," the report says. "These kinds of changes to societal values are likely to be achievable only over the long term and in ways that we have not yet imagined."