Thousands of animal species are permanently losing their habitats

Scientists warn that rising heat and rapid land change could reshape wildlife habitats faster than expected. A University of Oxford-led analysis warns that up to 7,895 land vertebrates could lose all suitable habitat by 2100.

It traced extreme heat and land-use change, converting natural areas into farms and cities, to see when habitats stop working.

How heat shapes wildlife

The work was led by Dr. Reut Vardi at the University of Oxford, and she studies climate stress in wildlife. Researchers mapped where 29,657 amphibian, bird, mammal, and reptile species live, then checked whether future conditions stay within their limits.

They used socioeconomic scenarios, storylines about population, energy, and land decisions, to compare futures with protection against ones with heavier pressures.

“It further stresses the urgency of conservation and mitigation actions globally to prevent immense losses to biodiversity,” said Dr. Vardi.

Heat spikes and wildlife

The team treated extreme heat events, hot runs lasting more than five days, as moments when animals face the highest stress.

For each species, they estimated a thermal maximum, hottest daily high seen in its range, using records from 1950 to 2005.

Even if average temperatures rise slowly, a hot spell can cause dehydration, failed breeding, and sudden die-offs in sensitive species.

The Intergovernmental Panel on Climate Change (IPCC) finds that human-caused warming has increased many temperature extremes since pre-industrial times.

When threats combine

Their results point to synergistic effects, combined harm bigger than each threat alone, when heat strikes places altered for people.

In the most optimistic scenario, species still faced both pressures across an average of 10% of their ranges.

Under the harshest future they modeled, the average species saw unsuitable conditions across 52% of its range.

The study counted suitable area, places meeting habitat and climate needs, and marked cells unsuitable once either factor crossed a line.

Regions where risk piles up

Hotter and more built-up conditions overlapped most clearly in the Sahel, parts of the Middle East, and Brazil.

Rapid growth in farms and cities can cut habitat into smaller pieces, and heat can make the remaining pieces harder to use.

The analysis worked on squares about 15 miles (24 km) wide, so it shows broad patterns but misses fine-scale shelter.

Because wildlife often depends on shade, water, and burrows, local management can sometimes reduce heat stress even in risky regions.

Heat hits certain wildlife harder

Amphibians and reptiles were projected to face greater losses than birds or mammals across every future path the study tested.

Many of those animals are ectotherms, relying on outside warmth for body temperature, so extreme heat can push them hard.

Species with smaller starting ranges tended to lose a larger fraction of their living space, leaving fewer options for survival.

Hot days can dry ponds and soils, hitting amphibians that need moisture for breathing and reproduction at the same time.

How hidden risks emerge

The Red List defines Data Deficient, as not enough information to assess extinction risk. It is a category that can hide trouble.

Under two of the four futures, over 77% of those species faced unsuitable conditions across at least half their range.

The same models flagged many Near Threatened along with Vulnerable, Endangered, and Critically Endangered species.

Limited records can come from remote habitats or hard-to-study behavior, so planning must consider unknowns instead of waiting.

How land change harms

When people build roads, fields, and towns, habitat fragmentation can trap wildlife in hotter corners. To project land change, the team used a dataset that tracks how forests, cropland, pasture, and cities expand over time.

Losing habitat also blocks dispersal, so animals may not reach cooler ground when heat pushes their sites beyond tolerance.

Because farmland often replaces mixed vegetation, it can raise local temperatures and reduce cover, compounding stress during hot spells.

Why parks still warm

Protected areas can reduce land conversion, but they cannot stop outside heat from spilling in as regional climates warm.

Some reserves could become hotter than the historical conditions used to set thermal limits, even if forests remain intact.

Conservation plans stress connectivity, safe routes that let species move between habitats, because isolated parks may become dead ends.

Managers can also add shade and water, restore wetlands, and limit nighttime light to reduce stress for heat-sensitive animals.

How wildlife escapes heat

Field work highlights microhabitats, small nearby spots with different temperature and moisture, that can let animals cool off during heat spells.

Tree cover, tall grass, leaf litter, and deep crevices can create cooler spots that help animals rest and feed.

Some species change activity times, hide during the hottest hours, or use wetter ground, but those options vary widely.

Large-scale maps cannot capture every creek bed or rocky ledge, so on-the-ground surveys remain essential for decisions.

Heat forecasts guide wildlife

The National Aeronautics and Space Administration (NASA), provides a dataset of downscaled climate data, global model output adjusted to local detail.

NASA’s collection blends several global climate models, helping researchers see whether patterns stay similar when any single model behaves oddly.

Uncertainty grows as NASA-backed projections stretch decades ahead, but consistent signals across many runs can still guide conservation choices.

Cutting heat-trapping pollution and protecting natural land both matter, because the study shows danger rises when those efforts fail together.

The study is published in Global Change Biology.

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