Extinction looms large over one in six of Earth’s species

Greatest risk in areas of shrinking habitats and difficulty migrating – especially tropics

One in six of the planet's species are likely to disappear if climate change continues unchecked, according to fresh research.

The losses will be particularly high in the tropics, a second study has found, suggesting that the tropical ecosystems may be exceptionally vulnerable to extinction risks.

Look out your window and count up any six species you see. Now realise that one might disappear because of climate change in the coming decades, says Prof Mark Urban of the University of Connecticut.

The losses could be as high as 18 per cent. “It depends what we do in terms of green house gas emissions,” he says.


He pulled together 131 different biodiversity studies to assess what climate change might mean in terms of lost species. He found that the loss of biodiversity didn't just follow the level of temperature change up or down, it was actually accelerating as temperatures climbed.

The greatest risk was in areas where shrinking habitats and difficulty migrating made it impossible for species to move away, places such as South America, Australia and New Zealand, he says.

If you assume international agreement unexpectedly arises and future temperatures increase by only two per cent then extinction risk would rise from its current 2.8 per cent to 5.2 per cent, Urban reports in his study, published Thursday in the journal Science.


But if warming continues on its current trajectory that will mean a 4.3 per cent rise in average temperature compared to pre-industrial days. In this case 18 per cent of species could face increased risk of extinction.

“Some species are very sensitive to these changes,” he says. The losses could include species that are important for food security, for the economy, for health or for cultural reasons, he says.

Extinction risk was studied in another paper released today in Science. Seth Finnegan at University of California, Berkeley and colleagues looked at pre-human extinction patterns back over 23 million years. These in turn were compared with how human activity and climate change affected different groupings of animals in different regions of the world.

They looked at thousands of different animals and groups including mammals, sharks and bivalves.

They matched these findings up against the global distribution of biodiversity threats from human activity and identified regions where the risk is particularly high. These were predominantly located in the tropics, which suggests that these tropical ecosystems could be particularly vulnerable to extinction, they say.

Dick Ahlstrom

Dick Ahlstrom

Dick Ahlstrom, a contributor to The Irish Times, is the newspaper's former Science Editor.