Extinction risk from climate change

• 1. Mechanisms Of Extinction Risk

  ›

  In 2019, the Australian government officially confirmed that the Bramble Cay melomys had gone extinct. This small rodent lived on a low-lying island in the Great Barrier Reef and was the first mammal to disappear due to human-induced sea level rise. Climate change pushes species beyond their ecological niches by altering temperature and weather patterns faster than they can adapt. Cold-blooded animals like amphibians, reptiles, and invertebrates struggle to find suitable habitats within 50 kilometers of their current location under mid-range warming scenarios. Extreme weather events increase in frequency and intensity, directly wiping out regional populations. Sea level rise floods coastal river systems, converting fresh water habitats into saline environments where indigenous species perish. The waters of Hudson Bay are now ice-free for three weeks longer than they were thirty years ago, affecting polar bears that rely on sea ice to hunt seals.

  616

• 2. Documented Species Losses

  ›

  The IUCN lists only 20 of 864 known extinctions as potentially linked to climate change, either wholly or partially. Evidence linking these losses to climate change is often considered weak or insubstantial. Snail species like Graecoanatolica macedonica and Pachnodus velutinus face extinction due to drought and habitat degradation. Fish such as Acanthobrama telavivensis and Tristramella magdelainae have gone extinct in the wild because of drought and loss of aquatic habitat. Frogs including Atelopus ignescens and Incilius holdridgei suffer from chytrid fungus combined with climate stress. Birds like Fregilupus varius and Gallirallus wakensis face threats from storms, overharvesting, and introduced diseases. In southeast Alaska, sea levels rise by 3.96 centimeters per year, contaminating streams and rivers with saltwater. This process stops sockeye salmon from reproducing in spring since spawning requires fresh water. The white lemuroid possum was once thought to be the first mammal driven extinct by climate change, but another population remains healthy 100 kilometers south.

  782

• 3. Global Risk Projections

  ›

  The IPCC Sixth Assessment Report projects that between 9% and 14% of assessed species will face very high risk of extinction under 1.5 degrees Celsius of global warming. If warming reaches 2 degrees Celsius, this figure rises to 12% to 29%. Under a 3-degree scenario, 15% to 48% of species could be at very high risk. A 2024 review paper suggests that 13.9% to 27.6% of all species might go extinct by 2070 under moderate emission scenarios. High-emission pathways could lead to 22.7% to 31.6% extinctions by the same date. Another synthesis of 5 million projections indicates that current trajectories threaten around 5% of species by the end of the century. Warming of 5 degrees Celsius would likely result in 15% to 30% of all species disappearing. Experts estimate that 1.5 degrees of warming threatens or drives about 25% of species to extinction, while 3 degrees could threaten 50% of them.

  54445

• 4. Vulnerability By Taxonomic Group

  ›

  Amphibians are particularly vulnerable, with salamanders being more than twice as threatened as other amphibian groups. At 2 degrees Celsius of warming, 11% of amphibians and 24% of salamanders face very high extinction risks. Reptiles show similar patterns; a 2023 study found that 56.4% of reptile species could lose some habitat by 2100 under high-warming scenarios. Invertebrates include pollinators, with 12% at very high risk if warming reaches 2 degrees Celsius. Corals are among the most vulnerable ecosystems; even at 1.5 degrees Celsius, only 0.2% of global coral reefs can withstand marine heatwaves. Insects account for the vast majority of invertebrate species, with up to 49% losing over half their geographic range under 3 degrees of warming. Birds like the Southern Yellow-billed Hornbill have seen breeding success collapse in the hottest parts of southern Africa's Kalahari Desert. Sea turtles in the Caribbean face skewed sex ratios due to rising temperatures, with projections showing only 0.4% hatchlings male by 2090.

  60697696

• 5. Regional Biodiversity Hotspots

  ›

  Madagascar is projected to lose 60% of its species under 2 degrees Celsius of warming. The Fynbos region in South Africa's Western Cape will lose one-third of its species, while Miombo Woodlands could lose 86% of birds and 90% of amphibians. In the Pacific Ocean, 15% to 62% of islands studied would be completely underwater or lose 50% to 99% of their area under sea level rise scenarios. Bangladesh faces potential loss of 2% to 34% of native butterfly species depending on emission pathways. European alpine plants like Viola calcarata are expected to go extinct in the Swiss Alps around 2050. Germany's Bavaria region has already pushed out cold-adapted grasshoppers and butterflies while allowing warm-adapted species to spread. Hawaii's native forest birds face extinction threats from avian malaria under high-warming scenarios. Coastal Alaska mountain goat populations may disappear between 2015 and 2085 in half of considered climate change scenarios.

  737980

• 6. Ecological Adaptation Limits

  ›

  Globally, only 5% of ectotherm species' present locations lie within 50 kilometers of a location that remains fully suitable by 2100. Random dispersal has an 87% chance of sending species to less suitable environments. Species in the tropics have the least extensive dispersal options, while temperate mountain species face the greatest risks of moving to wrong locations. Evolutionary tolerance to warming appears limited to 0.1 degrees per generation, which is too slow to protect vulnerable species. In Britain, spring butterflies now appear an average of six days earlier than two decades ago. The red deer population on Rùm island in Scotland gives birth three days earlier for each decade of study due to warmer temperatures. Antarctic hair grass is colonizing areas where survival was previously impossible. However, completely random dispersal often leads to extinction rather than adaptation. Artificial selection experiments show evolution can occur but at rates insufficient to match current climate change speeds.

  209895

• 7. Conservation Strategies And Mitigation

  ›

  Preserving habitats through protected areas like the 30x30 initiative is crucial for helping endangered species survive. Assisted migration involves actively transporting plants or animals to new habitats where they might thrive. The Torreya Guardians have implemented such programs to save the Torreya taxifolia tree from extinction. Moving polar bears to Antarctica would damage that ecosystem too severely to be viable. Captive breeding and embryo cryopreservation serve as last resorts when natural habitats are lost. Women in Zimbabwe's Hurungwe rural district place beehives at field borders to protect crops from elephants while supporting local livelihoods. Reducing future warming to the lowest possible levels remains essential alongside habitat preservation. Species extinct in the wild may be kept alive in artificial surroundings until suitable natural habitats return. These strategies aim to prevent further biodiversity loss while acknowledging the limits of human intervention.

  1542