From: Ed Stoddard and Spokes Mashiyane, Reuters
Published February 7, 2005 12:00 AM

Ancient Beasts Raise Questions about Climate Change

ROCKTAIL BAY, South Africa — The signs of the scuffle were fresh but it is a struggle that has gone on for tens of millions of years.


Just minutes before, dozens of tiny turtles had burst from the sand under the cover of darkness to make a mad dash for the sea by running a deadly gauntlet of ghost crabs.


"There's been action here. You can see the drag marks where a crab dragged a hatchling away," said Jeff Gaisford, communications manager for KZN Wildlife, the conservation body for South Africa's KwaZulu-Natal province.


Each year between October and February, hundreds of loggerhead turtles and their cousins, the gigantic leatherbacks, come to South Africa's northeast shores to build primitive nests in the sand and deposit their eggs.


One of the oldest reptilian orders, stretching back 200 million years, turtles have been doing this for a very long time -- and their resilience raises questions about the impact of climate and sea level change on biodiversity.


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Concerns about global warming are running high with the U.N.'s 128-nation Kyoto protocol, which seeks to curb emissions of carbon dioxide, set to come into force on Feb. 16.


The U.N. projects that overall temperatures will rise by 2.5-10.5 degrees Fahrenheit by 2100, mainly because of a build-up of carbon dioxide from cars, factories and power plants.


Such rapid change in global temperatures is seen by many scientists as a major threat to countless species, in conjunction with habitat destruction and other man-made threats.


Sea levels are also predicted to rise as glaciers and ice-caps melt and because water gets bigger as it warms through a complex process known as thermal expansion.


Some scientists believe that climate change could be contributing to the planet's sixth mass extinction -- periods when around two-thirds of all species have vanished -- and the first since the dinosaurs died off 65 million years ago.


But global temperatures and sea levels have been in flux for the last 200 million years -- and turtles are still around.


Hot Air?


"I don't think climate change is a huge threat to turtles unless they lose feeding habitat, such as coral reefs," said Dr Ronel Nel, a marine ecologist with KZN wildlife.


"I don't think sea level changes would affect them provided they have adequate nesting habitat ... There must have been climatic changes over the last 200 million years so one would expect them to deal with that."


By some estimates, sea levels have risen hundreds of feet since the last ice age 10,000 years ago -- and that event marked the end of a period of fairly rapid climate change that did not trigger large-scale extinctions.


Other scientists and observers see climate change as a far more significant factor.


Global warming and not a giant asteroid may have nearly wiped out life on Earth some 250 million years ago, an international team of scientists said this month.


In our own time, creatures such as polar bears could be wiped out as global warming thaws the polar ice, confining the animals to smaller and more isolated bands of territory.


"Species already are responding to changes in regional climate, with altered population sizes and breeding times," said a 2001 U.N. report on the issue.


"These responses suggest that many unique species will undergo complex changes with a few degrees of warming, which could lead to extinction in many locations," it said.


That may be bad news for polar bears -- but it does not necessarily herald a mass extinction.


There are also concerns that warming ocean temperatures could kill off large tracts of coral reefs which could prove bad news for turtles and other marine animals.


Back at Rocktail Bay on South Africa's northeast coast, the leatherback turtles are busy, with no less than eight spotted crawling from the sea to nest during a night out on the beach.


A few miles south of here and deep beneath the ocean's waves lies one of the few known populations of the coelacanth, a "fossil fish" that has been swimming the seas for about 400 million years.


Only found at certain depths -- usually below 100 meters -- there are worries that global warming could affect the coelacanth as well, as it appears susceptible to changes in the water temperature.


But like the turtles of the area, it has clearly survived big alterations in temperature and sea levels in the past.


This at least provides some hope for these ancient marine creatures -- but that doesn't mean that others won't succumb to human-induced warming.


And turtles face other man-made threats such as being hunted for soup or getting caught in fishing nets.


Source: Reuters


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