Global warming will lead to the extinction of one quarter of all species of plants and animals on Earth by 2050 unless greenhouse-gas emissions are drastically reduced, researchers have found in a study of six regions of the Earth.

The study examined the effect of global warming on 1,103 species of plants, mammals, birds, reptiles, frogs and insects in South Africa, Brazil, Europe, Australia, Mexico and Costa Rica. While some species might be able to adapt to climate change, the researchers used computer simulations that determined that many would die off as a result of global warming.

Greenhouse-gas emissions from cars and factories could make the Earth hotter than it has been in 10 million years, before most existing species evolved, said Chris Thomas, professor of conservation biology at England's University of Leeds and lead author of the study. The damage could be comparable to the dinosaurs' disappearance from the earth 65 million years ago, the researchers said.

"It's quite possible that large parts of the world will become barren wastelands, or at least their species diversity will probably drop dramatically," said Alison Cameron, a co-author of the study, which was published in the Jan. 8 issue of the journal Nature.

Species generally evolve fairly slowly, but the climate change on Earth is happening so fast that it's unlikely many will be able to adapt, Cameron said.

The United Nations said the report is more evidence that the world should adopt the Kyoto protocol, which aims to stop rising temperatures caused by human pollution. President Bush declined to sign the treaty in 2001, saying it was "flawed" and "unrealistic" because it did not include some of the biggest pollution offenders such as China and India.

"The industrialized countries are producing far higher (carbon dioxide) emissions per capita than other countries, with the U.S. heading the list," Thomas said in an e-mail. "Therefore, these countries need to take action most rapidly. In effect, we are exporting extinction."

He also said that industrialized countries have a major responsibility for developing technologies that can combat pollution, such as long-term carbon storage.

Global warming is the newest threat to the species of the Earth, the researchers said, on top of the destruction of certain environments such as rain forests. "The combination of increasing habitat loss and climate change together is particularly worrying," said co-author Lee Hannah of Conservation International in Washington, D.C.

The species facing the greatest threat include several Amazonian trees; South Africa's national flower, the king protea, and its relatives; the Spanish imperial eagle; and Boyd's forest dragon lizard in Australia. Birds like the Scottish crossbill might survive if they can manage to fly to Iceland.

Thomas said the majority of global leaders agree that something needs to be done, but he worries it will take too long for countries to agree on an approach. Meanwhile, damage to the environment will persist.

"The problem is that united action often runs up against the parochial conflicting demands of each country in turn," he said. "It is an immense risk not to change direction. If ever the precautionary principle should apply, it should be now."

Reuters contributed to this report.