When plants and animals are confronted with a significant long-term rise or drop in temperature, the need to survive compels them to seek out an alternative environment in which to live. International 'climate corridors' - links between natural areas in various countries - can make it easier for plants and animals to migrate.

Whether tigers and elephants will really be able to 'emigrate' in future depends on the results of a biodiversity summit being held this week in Japan, where climate corridors are high on the agenda with a view to protecting yet more plant and animal species from extinction.

At present, around 21 percent of mammals are endangered, 30 percent of amphibians and 12 percent of birds. The decline in biodiversity has not been this dramatic since the extinction of the dinosaurs, 65 million years ago, say scientists.

Agile frog
Agricultural ecologist Claire Vos is enthusiastic about the international climate corridors. Given larger areas in which to roam, species will be better able to adapt to the effects of climate change. Faced with excessively warm temperatures, animals and plants will be able to migrate to colder climes. She believes the Netherlands could soon be home to the agile frog and the Western Bonelli's warbler, which currently reside in more southern regions. Species found in the Netherlands, such as the European pied flycatcher and the black woodpecker will most likely head north.

The World Wide Fund for Nature is already hard at work to create international corridors in Africa and Asia. Frans Schepers of the WWF is keen to emphasise that the construction of links between natural areas is not the only way to protect species, but it is a very important one. He gives a number of examples, the first one in Asia.

Danger of isolation
"Take Sabah in Borneo," says Frans Schepers. "There we are working on a chain of forested areas along the River Kinabatangan, which is home to orang utans and elephants. Fragmentation of wooded areas means that the animals are in danger of becoming isolated. We are trying to link areas once again by transforming palm oil plantations into forest, and to create areas in which the animals can move around."

Endangered gorillas
Frans Schepers has another example, from Africa: "The border region between Cameroon and Nigeria is the habitat of the endangered Cross River gorilla. Only 650 of these animals remain. The gorilla's future is jeopardised by the fragmentation of the forest areas. We are now working to create links. We know this approach is working because we have found gorilla hair in areas where they would not venture previously.

"In the basin of the Zambezi and Okavango rivers, work is being carried out on an elephant corridor between Botswana, Namibia and Zambia. This is the environment in which the African elephant lives. Some areas are overpopulated but others are not. By creating corridors, we can give the elephants the chance to move into other areas."

Logging concessions
The Meso-American corridor is the biggest example of an international natural link, joining together an area crossing Mexico, Belize, Guatemala, Honduras, Costa Rica and Panama. This corridor, which measures an impressive 533,000 square kilometres, originated in Costa Rica where it was called the Path of the Panther. It has given rise to a single continuous area which offers wild animals the chance to survive.

But who will pay for these costly projects? This too is an issue that has to be resolved in Japan this week. "In addition to national foundations, companies and organisations such as the World Bank, another possible source might be the sale of logging concessions to FSC-approved companies," says Frans Schepers. The FSC is Forest Stewardship Council; its approval means the company engages in responsible forestry and wood management.

As regards the funding of these geographical connections, the Netherlands backs the wish of developing countries that those who use natural areas and consume the products that come from there should also pay for the climate corridor projects.