Global warming 'less threat to diversity than habitat damage by man'

GLOBAL warming may not have the catastrophic effect on the diversity of the world's species that has been forecast, according to a new book.

Plants and animals may actually be able to respond to the temperature rises that are expected to occur over the next century, the University of East Anglia's Professor Godfrey Hewitt claims.

Drawing on the fact that many species have survived ice ages without becoming extinct, Prof Hewitt believes man's destruction of habitats is a far greater threat to biodiversity.

The theory is put forward in Climate Change and Biodiversity, to be published this Friday.

Prof Hewitt, an evolutionary biologist, said: "Most [species] can probably cope with the small increases in temperature we are seeing. Far more serious would be a sudden large drop in temperature, possibly the beginning of a new ice age. This is linked to another real worry, which is the destruction by man of habitats where species have survived many such major climate changes."

The book suggests that the threat of global warming to biodiversity should take account of longer-term climate changes. Species have endured repeated global cooling and warming through several ice-age cycles, which for northern Europe oscillated between ice cover and conditions warmer than today.

Elements of certain species will move north as temperatures rise, leading to potential genetic change in those species. Prof Hewitt added: "Organisms may adapt to new conditions, change their range with suitable environments, or go extinct."

The migration of species may also lead to genetic change, and loss of genetic diversity, although this probably poses no threat to humans.