Climate change is already battering hundreds of animal species

Under pressure

By Anita Makri

Climate change is already harming around 700 species of mammals and birds. That means that warming is not just a theoretical future threat, and conservation work must focus on the “here and now”, says a new study.

It reviewed 136 studies published between 1990 and 2015, as well as modelling the risks to animals on the IUCN Red List of Threatened Species. It concluded that almost half of terrestrial mammal species and nearly a quarter of all bird species could already be negatively affected, without us even realising.

“We have the knowledge to take action,” says Lee Hannah, a conservation ecologist and senior researcher at Conservation International, a non-profit based in Arlington, Virginia. “Truly massive climate-triggered insect outbreaks have killed millions of trees in North America. Heat flashes in the oceans have killed corals and changed coral reefs in every ocean.”

A third of all species may be at risk of extinction, says Hannah, and the study shows the changes are happening already.

Lead author Michela Pacifici at the Sapienza University of Rome, Italy, says their results also show the most affected species are in highly developed areas or areas expecting a human population boom in coming decades. So conservation needs to focus more on monitoring in these locations and on “control of human demand for natural resources”, she says.

Risk assessment

The team assessed the risk to animals by looking at traits including body mass, population numbers, geographic range, reproductive rate and survival rate. If at least one of these shows a decline affecting half the animal population or more, they reasoned, it shows climate change is already taking its toll.

Applying their model, they estimated that 47 per cent of 873 species of threatened terrestrial mammals and 23.4 per cent of 1272 threatened bird species are showing signs of harm. Elephants, primates and marsupials are the most affected.

The reasons why species are affected vary. Some mammals are struggling to adapt as temperatures are changing too fast or because their diets are specialised. For some birds, living at high altitude means fewer opportunities to move to cooler areas, while seabirds and others that live close to water face fragmented habitats or algal blooms.

Some 92 per cent of existing data on species vulnerabilities that the study reviewed came from Europe and North America. Hannah says we can expect the tropics to be even more climate-sensitive, with massive changes already under way.

Journal reference: Nature Climate Change, DOI: 10.1038/NCLIMATE3223