Climate change forces moths to higher ground

Four decades ago researchers visited Borneo to examine moth populations. Today, they have found the animals now live 67m higher as temperatures have risen

• Juliette Jowit
• guardian.co.uk, Thursday 29 January 2009 12.44 GMT
• http://www.guardian.co.uk/environment/2009/jan/29/moths-climate-change-tropics

Global warming is forcing tropical species uphill to escape the rising temperatures at a rate of more than a metre a year, a new study from the mountains of Borneo suggests.

More than four decades after a group of undergraduate students visited the south-east Asian island in 1965, a team of British scientists returned to the same sites on Mount Kinabalu to repeat their survey of moths.

The group of six, including a member of the original trip, found that on average the insects had raised the altitude of their range by 67m.

Although the trip had only been repeated once so far, they did everything possible to repeat the original survey, travelling at the same time of year in July and August, using photographs to identify exact sites for moth traps, and even carrying out the work at the same phases of the moon. The researchers used light to attract moths which were then trapped by nets or in empty "egg boxes" designed so they could not crawl out.

The results are also supported by other studies of tropical species in Madagascar, Monte Verde and Cost Rica, and temperate species in North America and Europe, said Chris Thomas, professor of biology at the University of York.

"While this is the first example with insects, there are a few other tropical examples that are starting to emerge," said Thomas. "If you look across all those studies they are all showing the same response, and it's extremely difficult to think of any other possible explanation that was causing all of those."

I-Ching Chen, the PhD student who led the research, reported in the Proceedings of the National Academy of Sciences journal, said: "Our new study is good in that it increases the evidence available, but it is potentially bad for biodiversity."

While some species might survive by migrating up mountains to similar temperatures, others could find there is too little space, or even run out of habitat on the barren rocky peaks, warns the study.

"The fact that over however many tens of thousands or millions of years they have failed to expand their distribution away from those areas makes it vanishingly likely [that] in the next 50-100 years they'll suddenly be able to up sticks and find a cooler part of the world they can expand in rapidly," said Thomas.

In a paper in Nature in 2004, Thomas and 13 other experts analysed the habitats of 1,100 species in five continents and estimated on average one quarter were at risk of extinction.

The tropics make up only 12% of the landmass of Earth, but contain an estimated 60% of all species. Last year a paper in the PLoS ONE journal, published by the Public Library of Science in the US, warned the risk of extinction in the tropics was "escalating". The authors, Jana Vamosi and Steven Vamosi, of the University of Calgary in Canada, later estimated that 20-45% of tropical species were at risk of extinction.