When Heat and Habitat Loss Collide: The Double Threat Facing Wildlife

Here's a number that deserves more attention than it's been getting: 74%.

That's the proportion of animal habitats on Earth that could be exposed to heatwaves by 2050 if we continue on our current emissions trajectory. It comes from a major new study published in April, and it's striking enough on its own. But there's another layer to it that's arguably more alarming than the headline figure itself.

It's not just the heat. It's what happens when the heat arrives and the animals have nowhere left to go.

One Threat is Survivable. Two at Once is a Different Story

Scientists have a term for this: compound risk. The basic idea is that a single stressor, rising temperatures, say, or habitat fragmentation from land clearing, might be something a species can manage. Animals adapt. They shift their ranges, adjust their behaviour, move uphill or poleward as conditions change.

But when multiple threats arrive at the same time, that calculation changes completely.

The April study, published in the journal Nature Ecology and Evolution, looked at how exposure to extreme events including heatwaves, wildfires, floods, and droughts is projected to change for animal species across different emissions scenarios. What the researchers found was that the risks don't just add together.

They multiply.

An animal facing a heatwave in an intact, connected ecosystem has options. It can retreat to cooler refuges, find shelter in dense vegetation, move to higher ground.

An animal facing the same heatwave in a fragmented landscape, where the forest has been cleared in patches, where roads and farms cut across what used to be continuous habitat, has far fewer choices. The escape routes are gone. The refuges have been replaced by paddocks or plantations or car parks.

Oxford research reinforces this point specifically. Their analysis found that nearly 8,000 animal species may be at risk precisely from the overlap between extreme heat and land-use change. Not heat alone. Not habitat loss alone. Both, simultaneously, in the same places.

Which Animals Are Most at Risk?

The compound risk picture varies considerably depending on the type of animal and where it lives.

Marine invertebrates, including corals, jellyfish relatives, and sea anemones, face some of the highest exposure. This makes grim sense: oceans absorb the majority of excess heat from climate change, and these animals have extremely limited ability to relocate when conditions change. A coral cannot pack up and move to cooler water. It bleaches, and if the heat persists, it dies.

Arachnids and centipedes are also flagged as particularly vulnerable in the research, which may surprise people who picture spiders as essentially indestructible. But many species have very specific habitat requirements and limited movement ranges, making them more sensitive to localised changes than their hardiness might suggest.

For larger, more mobile animals, the picture is more mixed but no less concerning. Polar bears are the most well-known example of a species losing the very foundation of its habitat, Arctic sea ice is declining at a rate that is outpacing their ability to adapt. Migratory birds are increasingly arriving at breeding or feeding grounds to find conditions out of sync with what they evolved to expect. Freshwater fish are being squeezed between warming rivers and disappearing connectivity as water is diverted or dammed.

What all of these cases have in common is that the problem isn't any single factor. It's the combination.

Why This Changes the Conservation Conversation

For decades, conservation and climate action have largely been treated as separate problems, addressed by separate communities of scientists, policymakers, and advocates. Conservation people worried about land clearing, poaching, and protected areas. Climate people worried about emissions, energy systems, and global agreements.

The compound risk research makes a powerful case that this separation is no longer tenable, if it ever was.

Protecting habitat isn't just a biodiversity issue. It's a climate adaptation strategy.

When animals have access to large, connected, intact ecosystems, they are dramatically more resilient to the warming that is already locked in, regardless of what we do on emissions from here. Corridors that allow species to migrate between refuges, protected areas large enough to contain viable populations, restoration of degraded land, these interventions matter more, not less, as temperatures rise.

The good news, and there is some, is that this reframing is increasingly influencing how conservation funding and policy works. The 30x30 initiative, which aims to protect 30% of the world's land and ocean by 2030, is explicitly framed around both biodiversity and climate resilience. Several national governments have begun integrating habitat connectivity into their climate adaptation plans. The logic is the same whether you're coming from a biodiversity angle or a climate angle: intact ecosystems are the buffer.

The Difference Policy Makes

It's worth pausing on what the study found when it modelled different emissions scenarios, because the contrast is stark.

Under current trajectories, roughly the path we're on now, 74% of animal habitats face heatwave exposure by 2050. If warming is held to 1.5 degrees Celsius, in line with the Paris Agreement's most ambitious target, that figure drops substantially. The study doesn't argue that 1.5 degrees is risk-free for wildlife. It argues, clearly, that every fraction of a degree matters enormously when you're talking about whether animals have the time and space to adapt.

This is worth repeating, because it cuts against the creeping narrative that we've already blown past the point where mitigation matters. We haven't. The difference between 1.5 degrees and 2 degrees, or between 2 degrees and 3, is measured in tens of thousands of species and billions of individual animals. The decisions being made right now in energy policy, land use, and global climate negotiations are not abstract. They are directly shaping the conditions under which the natural world either adapts or doesn't.

And Now, Some Good News

The science of compound risk is sobering. So it feels important to end with a reminder that the story isn't only one of loss.

This week, conservationists in Wales counted 52,019 puffins on Skomer Island, a new record, beating last year's count by more than 8,000 birds. Coho salmon are returning to California's Russian River after decades of absence. North America's largest wildlife crossing has just opened in Colorado, reconnecting habitat that roads had severed for decades. And in Brazil's Amazon, deforestation just hit an eight-year low, with the area cleared between August 2025 and March 2026 falling 36% compared to the previous year, thanks to sustained policy enforcement under Environment Minister Marina Silva.

None of these wins are small. They are proof that when the conditions are right, when policy is enforced, when habitat is protected, when communities commit to restoration, the natural world responds.

The compound threat is real. So is the compound solution.

Sources: Nature Ecology and Evolution (April 2026); Oxford University biodiversity research; Imazon Brazilian Amazon monitoring report (May 2026); The Wildlife Trust of South and West Wales puffin count (May 2026).