Despite their apparent mobility, many birds will be threatened by climate change (Image: Paul Nicklen/NGS/Getty)

Between a quarter and a half of all birds, along with around a third of amphibians and a quarter of corals, are highly vulnerable to climate change. These findings have emerged from the most comprehensive assessment to date of the impact of global warming on life. Its results have led some researchers to warn of the need for unprecedented conservation efforts if we don’t cut our emissions.

The new assessment of climate change risk was performed by scientists from the International Union for Conservation of Nature (IUCN), the organisation that produces the Red List of Threatened Species. “When the Red List was invented, it was long before anyone worried about climate change,” says Wendy Foden of the IUCN in Cambridge, UK.

Red List assessments of extinction risk do consider climate change, but in a limited way. The main tools used in these earlier assessments are species distribution models, says Foden. These map out the climate conditions where a species lives now, then estimate how that liveable area will alter as the climate changes. In many cases, species’ habitable ranges will move and shrink, putting them at risk.


But that’s not enough to assess risk. Some species may be able to cope if their environment changes. Others may be particularly suited to evolving new adaptations that will allow them to acclimatise to the changing environment. And yet more species may simply move to new areas.

Pace of reproduction

Foden and colleagues tried to take all that into account in their new assessment. They considered how quickly species could relocate, and whether they were barriers like mountain ranges in their way. They also examined how rapidly species could evolve. For instance, species that reproduce quickly have a better chance of evolving new adaptations than those that do not.

“If you’re a narwhal and only breed once every two years, it’s not going to happen,” says Foden. Species with low genetic diversity are also slow to evolve.

“These ideas have been milling around,” says Chris Thomas of the University of York in the UK. “But the way they’ve clarified them will be really helpful.”

So far, the team has applied their criteria to all birds, amphibians and corals. Species were classed as highly vulnerable if their local climate is changing rapidly, they are sensitive to these changes, and have little ability to adapt or relocate.

The results make for grim reading. Among birds, 24 to 50 per cent of species are highly vulnerable, according to the team’s most optimistic and pessimistic forecasts, as are 22 to 44 per cent of amphibians and 15 to 32 per cent of corals. The figures are similar to those obtained in a 2004 study by Thomas, which estimated that 15 to 37 per cent of species will be “committed to extinction” by 2050 due to climate change (Nature, doi.org/c34wgp). “These are high percentages,” says Thomas.

“Safe” species at risk

What’s more, many of these species are not currently classed as threatened. Foden says that 17 to 41 per cent of birds are highly vulnerable to climate change despite being considered safe by the Red List.

Certain areas are hotspots of threatened species. For instance, the Amazon rainforest contains huge numbers of birds and amphibians that are highly vulnerable to climate change. Most Arctic birds are also highly vulnerable, as are corals in the Caribbean and the Coral Triangle in south-east Asia.

“The moment you start thinking about the magnitude of the conservation programme we might need to put in place, it’s mind-boggling,” Thomas says. Protected areas would need to be much bigger than at present to safeguard relocating species. Also, we would have to intervene to move many species, often to new countries. Such translocations are difficult and expensive, and in any case many countries don’t allow them.

The best thing we can do is cut greenhouse gas emissions. “Minimising the rate and extent of climate change will reduce the amount of action required,” says Thomas.

Journal reference: PLoS ONE, DOI: 10.1371/journal.pone.0065427