Human activity is so profoundly harming the health of the planet that around 1 million plant and animal species, not to mention bacteria and fungi, could go extinct over the next several decades, according to a summary of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services’ (IPBES) new report on biodiversity.

The hollowing out of ecosystems — forests teeming with wildlife turning into monocultural farmland or vibrant coral reefs giving way to barren algae mats — is creating “trophic cascades,” or chain reactions, that are undermining the global balance of wildlife in ways that threaten human society. Never before has an individual species caused such widespread annihilation and unless rapid action is taken to halt these trends, then the loss of life will be irreversible, according to experts who spoke with Global Citizen.

“We rely on nature for clean air, we rely on it for fresh water, we rely on it for the food that we eat — the very basic things that humans need to survive, much less thrive, come from nature,” Ellen Ketterson, director of the Environmental Resilience Institute at Indiana University, told Global Citizen.

“What we know is that everything is connected to everything else,” Ketterson, who was not involved in the report, added. “If you start plucking out species from ecosystems, then their stability will be destabilized and we don’t know where the exact tipping points will be. It’s much better to be safe than sorry.”

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The IPBES report isn’t based on new research. Instead, it’s a comprehensive review of more than 15,000 scientific papers and government figures by 150 experts from 50 countries. The report gives heft and cohesion to disparate and sometimes obscure scientific inquiries over the past few decades, fills in knowledge gaps, suggests possible interventions, and shows how advances in technology more clearly paint a picture of a planet in crisis.

“The release of the report is an intervention of awareness,” said Gabe Filippelli, director of the Center for Urban Health at the University of Indianapolis. “Nobody will take any action if they don’t see the problem.”

The report says that humanity has already caused a 20% reduction in global wildlife. Nearly 40% of amphibian species, 33% of marine mammals, and 30% of coral reefs could be gone within the century. More than half of all land animals could also lose the habitats they need to survive.

These figures join an already alarming array of examples of how the sixth mass extinction in the Earth’s history is underway. A 2018 report found that humanity caused the death of 83% of all wildlife, in terms of biomass.  

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Filippelli said that some of the drivers of mass extinction, such as climate change and ocean acidification, are hard to reverse because the greenhouse gas emissions causing these environmental shifts have already been released into the atmosphere. At the same time, he stressed that future emissions need to be curbed to prevent further damage to the planet.

Many of the drivers of biodiversity loss, however, can be swiftly addressed, he said.

“Some of this stuff is unstoppable, so we need to do the most we can to mitigate the negative impacts at the local level, while also keeping our eyes at the global level,” Filippelli said. "People sometimes have thrown up their hands at climate change, saying it's too multifaceted, but most of these things can be dealt with in our backyards."

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For example, governments can act immediately to stop global deforestation, which is primarily driven by agriculture, logging, resource extraction, and overdevelopment. Promoting reforestation over deforestation itself would have enormous ecological benefits around the world.

Resource extraction, which has tripled in the past decade, has caused 90% of global biodiversity loss.

Countries can create wildlife preserves safeguarded from exploitation that would allow species to recover. Similarly, human development and urban sprawl can be reconceived to prioritize sustainability. Instead of pouring concrete over soil and chopping down forests, developers and urban planners can create infrastructure that doesn’t interfere as dramatically with wildlife.

“The bacteria growing in a petri dish thinks life is just great until the last doubling when they hit the wall of the dish and run out of resources,” said Don Waller, professor of biology at the University of Wisconsin-Madison, as a way to illustrate the rapid depletion of the Earth's resources. “Animal biomass is mostly humans now. What we’ve done is chopped up nature, fragmented and isolated a lot of populations, and vastly reduced the abundance of most large animals — and this can’t go on much further.”

Pollution is another threat to wildlife that can be effectively mitigated by simply banning harmful toxins. Overfishing can be reduced through better global management of fisheries, and the spread of invasive species, which has increased by 70% since the 1970s, can also be slowed through better global regulation.

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Over the past several decades, these trends, and many others, have caused ecosystems to hollow out. For example, driving in Northern Germany at certain times of the year used to entail a windshield full of splattered bugs. Nowadays, those sorts of collisions rarely happen because insect populations are plummeting.

“We’ve seen the transitioning of diverse ecosystems to very simple ones,” Filippelli said. “It’s not that they don’t have life, it’s that they’re dominated by one or two organisms, instead of thousands.”

“The minute you lose a diverse coral reef to algae, you’ve basically lost most of the ecological and food niches, and you’ve quite literally lost the space niche, meaning coral reef themselves are a very complex 3D structures that allow a lot of different organisms to physically occupy that place, whereas an algae mat is basically a flat ecosystem.”

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The effects of this simplification on human society are hard to predict, but early signs show how it minimizes global crops yields and increases the spread of diseases.

“Just counting species may not sufficiently convey the risk we face and I think the report does a good job at explaining our interdependence,” Ketterson said.

“If we just go barreling on through, we’re going to be in a pickle,” she added.