Climate experts sound grim warning

Scientists have long agreed that climate change could have a profound impact on the planet. Now a team of climate experts has ranked the most fragile and vulnerable regions on the planet, and warned hey are in danger of sudden and catastrophic collapse before the end of the century. In a comprehensive study published recently the scientists identify the nine areas that are in gravest danger of passing critical thresholds or "tipping points" beyond which they will not recover. By some estimates, there will not be any sea ice in the summer months within 25 years. The next most vulnerable area is the Amazon rainforest, where reduced rainfall threatens to claim large areas of trees that will not re-establish themselves. The scientists also expressed concerns over the Boreal forests in the north, and have predicted that El Nino, the climate system which has a profound impact on weather from Africa to North America, will become more intense. Last year, the U.N.'s expert panel of climate scientists warned average temperatures could increase by as much as 6.4C by the end of the century, with a rise of 4C most likely. Such a rise would bring food and water shortages to vulnerable parts of the world, displace millions of people and wipe out hundreds of species. In the latest study, the scientists calculate Arctic sea ice will go into irreversible decline once temperatures rise between 0.5C to 2C above those at the beginning of the century, a threshold that may already have been crossed. There is already a 50 per cent chance that the Greenland ice sheet will soon begin melting unstoppably, though it could take hundreds of years to melt completely. The melt water would raise global sea levels by seven meters. A temperature rise of 3C could see more intense El Ninos, with profound effects on the weather from Africa to North America. Warming of 3C to 5C could reduce rainfall in the Amazon by 30 per cent, lengthening the dry season. The Boreal forests could also pass their tipping point, with large swaths dying off over the next 50 years. In Africa, more rainfall may regreen the Sahel region, but the West African monsoon could collapse, leading to twice as many unusually dry years by the end of the century.

The Indian summer monsoon is predicted to become erratic and in the worst case scenario, begin to flip chaotically, unleashing flash floods one year and droughts the next. Measurements of the western Antarctic ice sheet show the balance of snowfall and melting has shifted and it is now shrinking. According to the study, a local warming of more than 5C could trigger uncontrollable melting, adding five metres to sea levels within 300 years. Under the same warming, Atlantic currents that power the Gulf Stream could be severely disrupted.

The Hindu, February 3^rd 2008

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