FEELING THE HEAT
MARCH 6, 1997
The fastest rise in temperature for perhaps ten thousand years is having a dramatic effect on the brittle ecosystem of Antarctica. ITN reporter Andrew Veitch looks at how rising temperatures have changed the way penguins, seals and whales live and die in the shadow of the South Pole.
A RealAudio version of of this segment is available.
March 6, 1997:
Paul Hoffman, the editor-in-chief of "Discover Magazine" talks with Charlayne Hunter-Gault about the warming trend.
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Outside Links: Read a paper on global warming by a scientist at the U.S. National Climatic Data Center.
ANDREW VEITCH, ITN: Late summer in the crackling ice water of the Antarctic Peninsula. The leopard seals are waiting for their annual feast. Seals move faster underwater, but penguins are faster, so chasing them is a waste of energy. They wait in the channels the birds must use to reach their rookery and their ravenous young. On Torgason this year's chicks are fast losing their juvenile fluff. Within weeks their parents will leave to winter far out on the pack ice. The young must follow or starve. So now they're fattening on regurgitated krill, the tiny, shrimp-like creatures which fuel life in Antarctica. By the time they take their first swim, they'll be bite-size for the next link in the food chain. For the leopard seals the time of feasting is at hand.
In this climate timing is everything. The cycle of life must match the cycle of the ice, and the cycle is changing. This stretch of shoreline held a thriving rookery last year, but this year when the penguins returned to their nests it was snowbound. Only three chicks have survived. The temperature on the Antarctic Peninsula has risen by 2 and a half degrees Centigrade over the past 50 years. The warmer atmosphere holds more moisture, so precipitation is greater. At these latitudes that means, in general, more snow and more cloud to prevent it melting. The reproductive cycle of the birds is out of step with the weather.
ANDREW CLARK, British Antarctic Survey: There is a strong seasonal cycle in the ice and the ice dictates much of the biology we see, so I think it's probably true that if climate change starts to bite in the sea, the most direct effect will not be through a temperature change in the water, but through the effect of that climate change on the pattern of ice distribution and the behavior of ice.
ANDREW VEITCH: The ice is stained yellow by phytoplankton, algae feeding on sunlight. This is the base of the Antarctic food chain. The baby krill depend on it, and without krill, the web of life in Antarctica begins to fall apart.
SUSAN TRIVELPIECE, Montana State University: If the ice has extended over the krills' spawning ground, these larvae have their wintering grounds right above them, they have plenty of food to survive the winter; they'll live to the next summer and be a large group. If this ice does not extend over their spawning grounds, the larval krill die. As a result, there's not as much food for the penguins. So that's where we see the decline in the penguins.
ANDREW VEITCH: Records of the rookeries near Parma Station go back 25 years. The numbers of Adelie penguins have fallen by 19 percent. This year alone, after another warm winter, the numbers fell from 11,500 breeding pairs to less than 8,000. The numbers of Chin Strap penguins, however, are increasing. While the Adelies need packed ice, Chin Straps prefer open water. So in one way they benefit from warmer winters.
BILL FRASER, Montana State University: The worst possible case scenario obviously would be that the system changes quite drastically in terms of the distribution of species and that sort of thing but the way climate change seems to work, at least what we're seeing, is that it's not so much that the system is collapsing in some way. It's just that different species are replacing other species.
ANDREW VEITCH: A fur seal used to be rare sight on these islands. This summer, says Bill Fraser, there are 2,000 of them. And the numbers of elephant seals have tripled. Like chin strap penguins they prefer open water and the edges of ice flows. Seals like the same beaches as penguins, and that's breaking up the rookeries. If an elephant seal chooses to flop on a penguin's patch of pebbles, it's the penguin that moves. And these females who've come ashore to molt are comparatively small. A mature male weighs 4,000 kilos.
The colonies become fragmented, less able to defend themselves against marauding skewers. The skewers will take the chicks, as well as the eggs. It seems that colonies of anything less than 40 breeding pairs are easy prey. The environment here is extremely sensitive. What seems to be a tiny increase in temperature is having a massive impact on the ice, on the wildlife that depends on it. What happens if the temperature continues to rise? Well, the penguins will either move out or die out. Simon Brockington and Martin White are diving at the British Rotherer Base on Adelaide Island. The seas are rich in life.
SIMON BROCKINGTON, British Antarctic Survey: Every group is represented there, with the exception of the decapods, which is the crabs and the lobsters, but everything else is there in abundance. And this is really common. They can get a lot bigger than this.
ANDREW VEITCH: Instead of crabs and lobsters, the Antarctic has an aquatic version of the British wood louse.
ANDREW CLARK: One of the other things about working on polar regions is the water is cold. So here we've got the two of them. The male is larger than the female. The female is beneath, the male on top, and you see that he has a pair of claws at the front which enable him to grip the female really quite hard. And they will stay like this for weeks on end. One of the reasons that many of the animals that do get large in the Antarctic is because they do everything slowly. Their metabolism ticks over slowly; they grow slowly. The reproduce infrequently, and they live to a ripe old age. As I say, this one is probably thirty or forty years old at least.
ANDREW VEITCH: The fish have evolved antifreeze to keep their blood flowing. Adaptation to the cold makes them vulnerable to warming.
ANDREW CLARK: Here, the fluctuation between the seasons are quite small, only maybe one or two degrees Celsius, and many of these animals appear to suffer thermal stress, high temperature stress, at all of about 3 or 4 degrees Celsius, water which for us would be freezing cold. So that suggests that if there is a gradual warming of the water here, these animals might have a problem.
ANDREW VEITCH: Across the bay on Leoni, only island the plants are the most visible sign of the changes. Mossy banks are spreading over the rock. The plants are soaking up the sun. Pearlwort is flowering. So is the Antarctic grass.
ADRIAN HULSKES, Netherlands Institute of Ecology: This has spread quite fast over the last five or six years. The plants over here have been adapted for, for years, centuries, thousands of years to a very stable climate. And now since the last decade this climate is changing, and response to it by the plants is very rapid.
ANDREW VEITCH: Whales cannot respond rapidly. In the Bismark Strait a pair of Humpbacks feast on krill. Like the seals and penguins they're dependent on a food source that is dependent on ice. Now this brittle ecosystem is facing the fastest rise in temperature for perhaps ten thousand years.