The next mass extinction isn’t a future event to watch for on the calendar. By most scientific assessments, it has already begun. The question is how long it takes to reach the full threshold: a loss of 75% of all species, which is the standard benchmark for a mass extinction. At current rates of species loss, that threshold could be reached somewhere between 400,000 and 3.6 million years from now, depending on how many species actually exist on Earth.
That timeline sounds distant, but the mechanisms driving it are happening right now, and the damage is accelerating. To understand where things stand, it helps to look at what qualifies as a mass extinction, what has caused them before, and what’s different this time.
What Counts as a Mass Extinction
A mass extinction has a specific scientific definition: 75% or more of living species disappear within a couple million years or less. Earth has experienced five of these events over the past 450 million years, each reshaping life on the planet in profound ways. The most recent killed the non-avian dinosaurs about 66 million years ago when an asteroid impact triggered years of blocked sunlight and freezing temperatures. The worst, at the end of the Permian period roughly 252 million years ago, wiped out an estimated 90% of all species.
The other three had different triggers. The end-Ordovician extinction involved severe glaciation. The Late Devonian event may have been driven by the spread of forests fundamentally altering Earth’s chemistry. The end-Triassic extinction was caused by massive volcanic eruptions that created toxic, oxygen-depleted oceans in as little as 50,000 years. In every case, the cause was a rapid, large-scale disruption to the conditions that supported life.
Why Scientists Say It Has Already Started
The current rate of species loss is between 100 and 10,000 times the natural background rate. Under normal conditions, roughly one to five species go extinct per year across the entire planet. Today, the number is dramatically higher, and it is being driven entirely by human activity, something that has never happened before in Earth’s history.
A major 2022 review in Biological Reviews concluded that the sixth mass extinction has “probably started” and that the evidence for a biodiversity crisis is “overwhelming.” The 75% threshold has not been crossed yet, which is why some scientists describe it as a potential future event rather than a current one. But the trajectory is clear: if roughly 180 species continue to go extinct per century, 75% of all known species would be gone within about 400,000 years. If the true number of species on Earth is closer to 6.5 million (many remain undiscovered), the timeline stretches to around 1.8 million years. Both figures fall within the paleontological definition of a mass extinction.
The numbers already on the books are alarming. The IUCN Red List, the most comprehensive global inventory of species health, estimates that 44% of reef-forming corals, 41% of amphibians, and 27% of mammals are currently threatened with extinction.
Five Forces Driving Species Loss
Unlike past extinctions caused by asteroids or volcanic eruptions, the current crisis has five interconnected human-driven causes. The biggest is land and sea use change: converting forests, wetlands, and other natural habitats into farmland and cities. This destroys the ecosystems species depend on and fragments what remains into isolated patches too small to sustain populations.
Climate change is the second major driver. Average global temperatures have risen by at least 0.7 degrees Celsius since 1980, and the most vulnerable ecosystems, including coral reefs, mountain habitats, and polar regions, are already being reshaped. Species that can’t migrate or adapt fast enough are dying off.
The remaining three drivers are pollution (particularly devastating to freshwater and marine life), direct overexploitation of wild species through hunting, fishing, and harvesting, and invasive species that outcompete or prey on native wildlife after being introduced to new environments. These five forces don’t operate in isolation. A coral reef already stressed by warming water is far more vulnerable to pollution runoff, and a fragmented forest can’t support the same wildlife populations when invasive species move in.
What’s Being Done to Slow It Down
The most significant international response is the Global Biodiversity Framework, adopted in 2022 under the United Nations Convention on Biological Diversity. Its centerpiece is the “30×30” target: protecting at least 30% of the world’s land, freshwater, and ocean areas by 2030. That same framework calls for restoring at least 30% of degraded ecosystems by the same deadline and reducing nutrient pollution by half.
Other targets focus on reducing pesticide and chemical risks by at least 50%, bringing the loss of high-biodiversity areas close to zero, and ensuring that all land and sea areas fall under biodiversity-inclusive planning. These are ambitious goals with no enforcement mechanism, and progress so far has been uneven. But they represent the clearest global consensus on what would need to happen to change the trajectory.
What the Timeline Really Means
When people search for “when is the next mass extinction,” they’re often expecting a date. The honest answer is that the process is underway but the finish line is hundreds of thousands of years away at current rates. That’s both reassuring and misleading. Reassuring because the full catastrophe isn’t imminent. Misleading because the damage compounds over decades, not centuries, and the species disappearing now aren’t coming back.
The practical reality is that you don’t need to lose 75% of species before the consequences become severe. Losing pollinators disrupts food production. Losing predators destabilizes ecosystems. Losing coral reefs eliminates coastal protection and fisheries that hundreds of millions of people depend on. The extinction crisis doesn’t need to hit its technical threshold to reshape human life on Earth. In many places, it already is.