Biodiversity encompasses every living organism on the planet, from microscopic gut microbes to the largest whales roaming the world’s oceans.
Scientists describe nature as functioning like a team, where every species performs a critical role that supports the broader system humans depend on.
When species from trees to animals work in concert, they regulate weather patterns, maintain soil health, purify water supplies, and underpin global food production through what are known as ecosystem services.
“It is really an abstract concept, but we experience it absolutely every day,” said Rebecca Shaw, chief scientist at conservation group WWF. “And we almost never think about it when nature is functioning.”
Over the past 52 years, monitored vertebrate populations have collapsed by an average of 73%, with freshwater ecosystems suffering the steepest decline at 85%, according to WWF’s Living Planet report.
Separate studies suggest that one million animal and plant species now face extinction unless humanity dramatically reduces its pressure on the natural world.
“It is a really steep decline,” Shaw said. “What it’s telling us is that nature is in trouble, and it’s an early warning indicator of the fabric of life that we depend on for freshwater and food and for clean air is unravelling.”
Thousands of policymakers, business leaders, and civil society representatives are meeting in Yerevan, Armenia for COP17, the latest UN biodiversity summit, to advance commitments aimed at reversing nature loss by 2030.
The economic consequences of ecosystem decline are already measurable, with one University of Waterloo study finding that wetlands in Southern Ontario alone provide C$4.2 billion worth of water filtration services each year.
Some 85% of the world’s wetlands disappeared between 1700 and 2000, and as they vanish, water quality deteriorates, dramatically increasing the cost of treatment for communities that depend on clean sources.
More than 75% of global food crop types rely at least partly on animal pollination, making the documented decline of bees, bats, and other pollinators a direct threat to food security.
A recent UK government report stated that every critical ecosystem is on a “pathway to collapse,” warning that nature’s decline posed a grave threat to global food supply and geopolitical stability.
“The UK, like many other countries, relies on imports for much of the food and so is reliant on ecosystems around the world,” said Louise McRae, a research fellow at the Zoological Society of London. “This is why we need to care about global biodiversity.”
Biodiversity also forms the foundation of modern medicine, with approximately 50% of human medicines derived from natural compounds, including penicillin, which is produced by a mold and estimated to have saved over 500 million lives.
Around 70% of cancer drugs come from natural products or synthetic compounds “inspired by nature,” according to the World Health Organisation, meaning biodiversity loss directly threatens future medical discovery.
Keystone species, those that play a disproportionately large role in their ecosystems, illustrate how the loss of a single organism can cascade across entire environments with devastating consequences.
Wild oyster populations have suffered massive declines, with 85% of their reefs lost worldwide, removing a species that filters up to 50 gallons of water per day and protects coastal communities from storm surges.
“No one would ever think they did anything but sit in a shell and be slimy,” Shaw said of oysters. “But you lose oysters, you can lose water filtration and clean water, you can lose the habitat for many other species that we interact with or sometimes consume.”
One study links the decline of red foxes in North America to the spread of Lyme disease, a tick-borne illness that directly affects human health, illustrating how species loss can accelerate disease transmission.
Despite alarming trends, both Shaw and McRae argue that conservation successes, including the recovery of green sea turtles and the rebound of sea otter populations on the US Pacific Coast, demonstrate that nature can recover when given the chance.
“You can see that ripple effect that really had an obvious and a measurable impact. But critically, it can be reversed,” said McRae, noting that biodiversity loss and climate change are intertwined problems with joint solutions.
“We’re learning how to turn things around at very small scales,” said Shaw. “Now the real challenge is to turn things around at very big scale so we can see it in the global indicators.”
