Only a handful of animal extinctions have been directly and officially linked to climate change so far, but the confirmed cases paint a clear picture of how rising temperatures, shifting weather patterns, and sea level rise can wipe out a species. The most well-documented examples are the Bramble Cay melomys, a small Australian rodent, and the golden toad of Costa Rica. Beyond those, climate change is acting as a threat multiplier, pushing already vulnerable species over the edge by spreading disease into new territory and destroying habitat.
The Bramble Cay Melomys: First Mammal Lost to Sea Level Rise
The Bramble Cay melomys was a small brown rodent that lived on a single tiny coral island in the Torres Strait, between Australia and Papua New Guinea. In 2019, the Australian government officially declared it extinct, making it the first mammal known to have been driven to extinction by human-caused climate change. The animal likely disappeared sometime between 2009 and 2011.
Bramble Cay is a low-lying island made of coral rubble and sparse vegetation. As sea levels rose, increasingly frequent high tides washed over the island and destroyed the plants the melomys depended on for food and shelter. Over 90% of the cay’s vegetation was lost after 2004 due to repeated seawater flooding. With nowhere else to go and no food left, the population simply vanished. The melomys had the misfortune of occupying one of the most climate-exposed habitats on Earth: a flat speck of land barely above the waterline.
The Golden Toad of Costa Rica
The golden toad was a striking, bright orange amphibian found only in a small area of cloud forest in Monteverde, Costa Rica. It was last seen in 1989 and is now considered extinct. Its disappearance became one of the earliest and most widely cited examples of climate-related extinction, though the story is more complex than rising temperatures alone.
Research published in the Proceedings of the National Academy of Sciences traced the toad’s demise to an exceptionally dry period caused by the 1986-1987 El Niño event, one of the longest and driest stretches Monteverde had experienced in a century. El Niño events in that region cause higher temperatures, reduced cloud cover, and significantly less moisture during the dry season. Starting with the powerful 1982-1983 El Niño, the number of consecutive dry days per year increased sharply in the cloud forest.
The drought hit during the golden toad’s breeding season in 1987, forcing the remaining population to crowd around a few surviving wet spots. That concentration made the toads fatally vulnerable to a deadly skin fungus called chytrid, which spreads easily when amphibians are packed together in shrinking pools of moisture. The combination of climate-driven drought and disease wiped out the entire species in just a few years. Scientists now view this as a case where climate variability didn’t just stress the population but actively created the conditions for a pathogen to deliver the final blow.
Hawaiian Honeycreepers and Climate-Driven Disease
Hawaii’s honeycreepers are a group of colorful forest birds that evolved from a single ancestor into more than 50 species found nowhere else on Earth. At least 10 of those species are already extinct, and several more are on the verge. While habitat loss and introduced predators played major roles in earlier declines, climate change is now the primary threat to the survivors, and it works through an unexpected mechanism: mosquito-borne disease.
Mosquitoes arrived in Hawaii accidentally in the 1800s, carrying avian malaria and avian pox. Native honeycreepers had never encountered these diseases and have almost no resistance to them. For decades, the birds survived by retreating to high-elevation forests where temperatures were too cool for mosquitoes to thrive. Those mountain refuges functioned as disease-free zones.
As temperatures climb, mosquitoes are breeding at higher and higher elevations, shrinking the safe habitat year by year. Modeling research warns that this combination of climate change, past land-use changes, and invasive species will likely drive several more honeycreeper species to extinction, particularly on the island of Kauai, which has the least remaining high-elevation forest. Species like the Kauai creeper and the akikiki are now critically endangered, with wild populations in the low hundreds or fewer. For these birds, climate change doesn’t kill directly. It opens the door for a disease that does.
Coral Reef Species on the Edge
No coral reef fish species has been officially declared globally extinct due to climate change yet, but local extinctions have already occurred, and the broader trend is alarming. After the massive 1998 coral bleaching event in the Seychelles, at least four fish species disappeared entirely from the inner islands, including the tubelip wrasse, a species that feeds directly on coral mucus. Whether those populations recover depends on whether the reef itself recovers and whether fish from unaffected areas can recolonize.
Species most vulnerable to climate-driven reef collapse share a few traits: they depend heavily on live coral for food or shelter, they occupy small geographic ranges, and they exist in low numbers. The chevroned triangular butterflyfish, for instance, ranks among the most vulnerable to global extinction because it has a restricted range, limited depth tolerance, and low population density. When a bleaching event kills the coral these fish rely on, they have few options. Reef specialists can’t simply relocate to a different habitat type.
How Climate Change Multiplies Other Threats
Most extinctions don’t have a single cause. Climate change typically acts alongside habitat destruction, invasive species, pollution, and overhunting. What makes it so dangerous is that it amplifies all of those other pressures simultaneously. A species that might survive logging or a new predator may not survive both of those stresses plus a shifting climate.
The current rate of vertebrate species loss is up to 100 times higher than the natural background rate, according to a study in Science Advances. That background rate, roughly two mammal species per 10,000 species per century, has been the norm for millions of years. Habitat loss and overexploitation are still the leading direct causes today, but climate change is an increasingly significant driver that is expected to overtake the others as warming accelerates.
What Warming Projections Mean for Species
The difference between moderate and severe warming translates directly into how many species lose viable habitat. According to the IPCC’s Special Report on 1.5°C, at 2°C of global warming, 18% of insect species, 16% of plant species, and 8% of vertebrate species are projected to lose more than half of their geographic range. At 1.5°C, those numbers drop to 6% of insects, 8% of plants, and 4% of vertebrates. Losing half your range doesn’t guarantee extinction, but it dramatically raises the odds, especially for species that are already rare or confined to a single habitat type.
The pattern across every confirmed and probable climate-linked extinction is the same: species with tiny ranges, specialized diets, or limited mobility are hit first. An island rodent that can’t swim to higher ground, a mountaintop frog with nowhere cooler to go, a forest bird trapped between rising disease and shrinking habitat. Climate change finds the most vulnerable species and removes their last margin of survival.