Global warming may create 'dead zones' in the ocean that will be devoid of fish and seafood and endure for up to two millennia, according to a study published. Its authors say deep cuts in the world's carbon emissions are needed to break a trend capable of wrecking the marine ecosystem and depriving future generations of the harvest of the seas.In a study published online by the journal Natural Geoscience, scientist in Denmark built a computer model to simulate climate change over the next 100,000 years. At the heart of their model are two well-used scenarios, which use atmospheric levels of carbon dioxide (CO2), the main greenhouse gas, as an indicator of temperature rise.\under the worst scenario, CO2 concentrations will rise to 1,168 parts per million (ppm) by 2100, or about triple today's level. Under the more optimistic model, CO2 will reach 549 ppm by 2100or roughly 50 percent more than today.The temperature rise that either yield depends on several factors: when the peak in carbon emissions is reached and how quickly it falls, and whether the warming unleashes natural triggers, or tripping points, that enhance or prolong the warming in turn.Taking such factors into account, the scientists predict a possible rise of around five to seven degrees Celsius over the pre-industrial times under the worst scenario, there will be warming of roughly between two to four C.Either scenario spells bad news for the ocean, said Jens Olaf Pepke Pedersen, a physicist at the Technical University of Denmark.Under the worst scenario, warmer seas and a slowdown of ice an circulation will lower marine oxygen levels, creating "dead zones" that cannot support fish, shellfish and other higher forms of marine life and may not revive for 1,500 to 2000 years if you stopped all carbon emissions, the ocean would still need hundreds of more years to cool, he said.
The News Indian Express, 26h January 2009.
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