Animal Populations Fell by 68% in 50 Years and It’s Getting Worse

Food production and other human activities are destroying the very systems they rely on, according to a new study.   

Animal Populations Fell by 68% in 50 Years and It’s Getting Worse
A kangaroo stands in front of a burned forest in Lithgow, New South Wales, Australia. (Photographer: Brendon Thorne/Bloomberg)  

The world is losing its mammals, birds, amphibians, reptiles and fish, and with them, the security of ecosystems that have supported humanity since it first emerged.

That’s the conclusion of the Living Planet Report 2020, a biannual assessment by World Wildlife Fund and the Zoological Society of London, which records the decline in vertebrate life. This year’s report, released Wednesday, shows that these animal communities shrunk on average 68% between 1970 and 2016. Parts of the world are much worse off. The tropical Americas have seen animal populations decline 94% in the same period. The size of observed animal communities in or near freshwater globally have fallen by 84%.

The authors put half the blame on changes to how we use land and the sea, citing such things as clearing ecologically important forest and freshwater use. Overfishing and hunting, invasive species, pollution and climate change round out the main causes of the global animal population crash. 

The report delivers a tough overall message. It suggests that continued human abuse of the planet may lead to collapse of the very natural systems and resources that allowed global civilization and modern societies to persist in the first place. And, they say,  humanity is demonstrably to blame, and the damage is unprecedented in speed and vastness within human history.

These conclusions come amid reports that nations have not lived up to commitments made in recent years to address biodiversity loss. This year was supposed to be a consequential one for addressing the issue. But the underlying problem remains. 

The Living Planet Index, the backbone of the report, measures the size of vertebrate populations. That’s different from identifying threatened or extinct species, which may indicate little about the overall health of an ecosystem and, consequently, the natural services provided to people, said Rebecca Shaw, WWF’s chief scientist and chair of the report’s steering group.

“One of the things that science has told us in the last decade so clearly is that we depend on intact natural systems and intact natural ecosystems, in all its component parts, to deliver those things we count on every day: clean air, clean water, pollination, a stable climate, food, healthy soils to produce the foods we eat,” Shaw said. “And what this index tells you is a very important component of that health is declining and declining fast.”

The authors did not mince words. They say that the evidence for biodiversity destruction is “unequivocal.” This word carries a great deal of meaning. Given their penchant for nuance and skepticism, scientists are loathe to say that anything is 100% true. But for more than a decade “unequivocal” has been climate scientists’ pentasyllabic alarm for grim seriousness. Using it to the same effect in the Living Planet Report 2020 elevates biodiversity loss to the level of trouble reserved for climate change, and entwines the two global environmental dilemmas. 

“I used the word very purposefully,” said Robert Wilson, author of an early Living Planet Report 2020 chapter and a former leader of both the UN Intergovernmental Panel on Climate Change and its biodiversity counterpart. “I want to make sure that everybody understands that the evidence is ‘unequivocal’ or ‘absolutely certain’ or ‘beyond doubt’.”

The report is littered with uncharacteristically bold and direct statements that make clear how they interpret the evidence they’ve compiled from 4,392 different vertebrate species across 20,811 populations. Rarely are they more straightforward than in a chapter on the health of soil ecosystems: “Soil biodiversity keeps us alive, so we need to ensure that we stop destroying it.” Pesticides, erosion and paving over land all contribute to soil’s degradation or demise.

This year’s report draws on powerful computer models to simulate policies that could avoid biodiversity loss. The “Bending the Curve Initiative” uses seven sophisticated Earth system scenarios to explore ways to both slow the trend and make sure the world’s growing population is fed. This initiative was published simultaneously Wednesday in the journal Nature.

Any solutions are a heavy lift, the authors conclude, but by changing what the world eats, and how it produces the food it consumes, nations can almost halve expected biodiversity loss. The measures include expanded conservation, increasing agricultural yields, eliminating food waste, and halving global meat intake. 

Doing these things is technically and economically possible “but designing and implementing policies that enable such efforts will be challenging and will demand concerted leadership,” David Leclère of the International Institute for Applied Systems Analysis and colleagues write in Nature

The report joins a large and expanding library of bad news. Scientists warned for years that temperatures would rise, California fires would grow, hurricanes would intensify, and potential pandemics would escape deforested areas to cities. What these earlier predictions have in common is that they came true.

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