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Climate change and biodiversityPosted: 06 May 2008
Climate change will have a powerful effect on biodiversity. It will directly endanger the habitats of many species, and for endangered species it may be the final blow that pushes them over the brink into extinction.
- Coral reefs, the rainforests of the sea, are under increasing stress from higher ocean temperatures brought on by climate change. Since 1998, many of the world�s tropical and sub-tropical reefs have been damaged by coral bleaching, triggered when higher temperatures cause the coral polyps to lose their symbiotic algae. Once this insidious process begins, the coral communities begin to die.(For further information, see Status of Coral Reefs of the World).
- Another major bout of coral bleaching took place in 2002. According to the coral reef Information Network known as ReefBase, some 430 cases of coral bleaching were reported that year, most of them on Australia�s Great Barrier Reef, the largest coral community on the planet.
- Coral reefs are economically, socially and culturally important. The Great Barrier Reef contributes nearly $7 billion annually to the Australian economy, generating some 65,000 jobs. Some of the reef structure is over 10,000 years old; virtually impossible to rebuild once it has been destroyed.
- Coral reef megafauna (for instance, sharks, turtles and dugongs) continue to decline rapidly due to a combination of climate change, habitat loss and over-harvesting.
- When temperatures in the North Pacific rose 6 degrees Centigrade above normal in 1997, local salmon populations crashed.
� Norbert Wu/Still Pictures
Loss of wetlands
- A sea level of one metre would threaten half the world's coastal wetlands of international biodiversity importance.
- A 3-4 degree C warming could destroy up to 85 per cent of the remaining wetlands in semi-arid southern Europe.
Disappearance of tundra
- Under global warming forests will move north, displacing the Arctic tundra, which is the breeding area for millions of Arctic water birds. A 40 per cent loss of tundra would mean that 4 to 5 million geese and about 7.5 million Calidrid waders could lose their habitat. The worst affected birds are likely to be the already critically endangered Red Breasted Goose, the Tundra Bean Goose, the Spoon-Billed Sandpiper, and the Emperor Goose.
- Even with a mild global increase in temperature of 1.7 degree C, these birds would lose more than 50 per cent of their habitat. A more radical warming of 5 degree C would destroy 99 per cent of the habitat of the Red Breasted Goose.
Shifting of ecological zones
- To cope with a warming of 2 degrees C over a century, species at mid-latitudes would have to shift about 400 km towards the poles, or climb about 400m uphill. Such migration rates are difficult to achieve.
- Trees with wind-born seeds can move at most 100-200 km a century, but most deciduous species such as walnut, chestnut and oak can move only 10-15 km a century.
Species at high risk from global warming
Monarch Butterfly on milkweed.
- According to the World Wide Fund for Nature, species at very high risk from global warming are: Giant Panda, Polar Bear, Indian Tiger, Reindeer, Beluga Whale, Rockhopper Penguin, Snow Finch, Harlequin Frog, Monarch Butterfly and Grizzly Bear.
- Global warming has already caused probable extinctions. The only known population of golden toad (Bufo periglenes), discovered in the Monteverde cloud forest, of Costa Rica, has have not been seen since 1986-87 after very low rainfall and high temperatures during an El Ni�o event. Some 20 out of 50 amphibian species went locally extinct at around the same time.
WWF Climate Change Campaign
For further information on the impact of climate change on biodiversity, link to Changing nature in a warmer world featured on our topic site on Climate Change.