climate change is forcing plants and animals away from their native habitats to more congenial ones. A recent survey of plants in the uk found that species favouring higher temperature like orchids and ferns that used to be found in southern parts of the country are now flourishing in the north, too. Changes have been observed in populations and distribution of as many as one-third of all species since 1987, says the survey carried out by Plantlife International, a uk- based conservation organisation and the Botanical Society of British Isles.
Climate change such as warming up of atmosphere affects habitat (see table: Eco-effects), forcing plants and animals to disperse and migrate. But if a physical barrier prevents movement, then species could die out. "We are going to see a lot of extinctions, particularly of species that are not able to move quickly enough," says Katherine Stewart of Plantlife International.
Hardest hit Climate change has hit insects (like butterflies) and birds the hardest. Migratory birds that cover large distances have been unable to cope. The breeding period of birds usually synchronises with a time when food is available in plenty. But climate change has thrown this system out of gear. According to a study conducted at the Groningen University in the Netherlands, climate change has led to food shortages during the breeding period of several species, causing their populations to decline (Nature, Vol 411, No 6835, May 17, 2001).
The State of
uk 's Birds 2004
released last year (see ' uk
birds hit', Down To Earth
, September 30, 2005) said the numbers of some species considered secure were declining alarmingly. Seven of the nine common species of wading birds shifted from the 'warm west' to the 'colder east' in response to milder winters, the report said.
Climate change is affecting the seas, too. In the north Bering Sea, which is frozen for most of the year, the seasonal melt is starting earlier and there is less ice in general, says a us
study ( Science
, Vol 311, No 5766, March 10, 2006). This is causing grey whales to move farther north to follow the cold water, while animals like the walrus and sea birds are facing a food shortage. More disease
A growing body of work is also linking climate change to the spread and re-emergence of certain human and animal diseases.
Poor countries face a dramatic rise in deaths from disease and malnutrition as a direct result of climate change, says a study published in Nature
(Vol 438, No 7066, November 17, 2005) .
Increases in temperature and precipitation have facilitated the spread of vector-borne infectious diseases such as malaria and dengue in most developing countries in the tropical region. who
says that at least 30 diseases may be making a comeback in poor countries because of climate change.
A warmer climate is causing diseases such as the West Nile virus and malaria to spread to North America. The West Nile virus, which was unknown in North America until a decade ago, has infected more than 21,000 people in the us
and Canada, killing more than 800.
Climate change models in the 1990s had predicted change in species distribution, habitat, emergence of new diseases and sea level rise -- all of which are coming true. In one of its worst effects, climate change altered patterns of a fungal infection, leading to the extinction of two-thirds of tropical harlequin frog species in Central and South America (Nature
, Vol 439, No 7073, January 12, 2006). With the Australian Greenhouse Office recently claiming that global temperature will rise more than previous studies indicate, scientists say more extinctions seem inevitable.
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