Tuesday August 29, 2006
Global warming scourge
Unusual things are happening in the oceans, and they may be triggered by global warming. ALISTER DOYLE reports.
SOUTH American Red Devil squid found off Alaska and jellyfish plaguing the Mediterranean may point to vast disruptions in the seas linked to global warming, pollution or over-fishing. Fish such as salmon and mackerel have also been spotted in the Arctic, far north of their normal ranges.
“There will be some places where ocean productivity will increase,” said Ron O'Dor, senior scientist of the Census of Marine Life, a 10-year project in more than 70 nations to map the diversity of the oceans. “The story of global warming is going to be good for some people and bad for others.”
Many scientists say that gases emitted by burning fossil fuels – coal, gas and oil – are blanketing the planet and driving up temperatures, threatening to spur more floods, heatwaves, erosion and rising sea levels.
Warmer oceans are likely to add to older marine threats such as pollution and over-fishing and upset the habitats of marinelife. As species shift, tropical regions, or almost enclosed seas such as the Mediterranean where fish cannot swim far if the water gets uncomfortably warm, may be among the most vulnerable.
“Areas close to the equator will most likely be the losers while the northern or southern areas might be the winners,” said Harald Loeng, head of research in oceanography and climate at the Norwegian Institute of Marine Research.
“It’s most likely that some of the species in the North Sea like cod will move north ... and be replaced by anchovies and sardines,” he said.
Some studies suggest that the Arctic sea ice, for instance, could melt in summers by 2100. As ice recedes, the extra heat and sunlight will help plankton grow and so feed more fish.
Over-fishing of more valuable fish stocks might be partly to blame for the squid population explosion as it removes big predatory fish like tuna, marlin and swordfish.
And a spate of jellyfish stinging holidaymakers on Mediterranean beaches this summer, for instance, may be part of wider changes such as global warming, or merely a freak.
And salmon have been caught north of the Bering Straits between Russia and the United States in recent years. They have also swum from the north Atlantic to once icy seas off northern Canada.
“It seems pretty clear that has to do with climate change. The conditions there have never been suitable for these animals before,” said O’Dor.
Among other changes, tropical coral reefs could die off in warmer waters. Many reefs, often known as “nurseries of the seas” are struggling with higher temperatures. Global sea levels could rise by 9cm to 88cm by 2100. That could cut the amount of sunlight reaching slow-growing corals, which co-exist with light-dependent algae.
Meanwhile, a slightly more acid sea linked to a build-up of greenhouse gases in the atmosphere could make it harder for creatures like lobsters or oysters to form shells. They might end up too soft and vulnerable to predators.
Still, fish stocks have often varied mysteriously. In 1599, for instance, herring failed to appear along the Norwegian coast.
The locals widely believed that God was unhappy because of thieving, drunkenness and fighting among fishermen. – Reuters