Some of the ponds which have been around for thousands of years in High Artic are drying up because of global warming, according to two researchers. Ancient ponds in the Arctic drying up during the polar summer as warmer temperatures evaporate shallow bodies of water illustrates the rapid effects of global warming, threatening bird habitats and breeding grounds and reducing drinking water for animals.
John P. Smol of Queens University in Kingston, Ontario, and Marianne S. V. Douglas of the University of Alberta in Edmonton have been studying about 40 ponds on Ellesmere Island in northern Canada since 1983.
AdvertisementWhen they went back last year, after an absence of a year, permanent ponds which previously had been up to a meter deep were drastically shrunken or even dry.
Their measurements had shown the water had been going down, but they were taken aback to find that about 40 well-studied pools — among them Camp Pond, Cape Herschel Lagoon and Beach Ridge Pond — were fractions of their former size, or totally gone.
"The final ecological threshold for an aquatic ecosystem is loss of water," said biology Prof. John Smol "These sites have now crossed that threshold"
"A key 'tipping point' has now been passed: Arctic ponds that were permanent water bodies for millennia are now ephemeral," These ponds were substantial bodies of water; Cape Herschel Lagoon, once 160 meters by 35 meters and a meter deep, "had only a small shallow puddle" (23 meters by 11 meters and 10 centimeters deep) in one basin when the scientists sampled it on July 13, 2006. Camp Pond, 20 meters by 40 meters, and Beach Ridge Pond, 100 meters by 60 meters, were completely dry.
Smol likens the warming conditions to a pot of soup on a stove." If you take the lid off, it is similar to what we are observing in these ponds. The soup will slowly decrease in volume and it will get saltier and saltier as the water evaporates, leaving the salts behind." That same evaporation process is taking place with these ponds, he said. So there is a rise in the concentration of salt in the remaining water.
Weather records show there has been no decline in rain and snowfall in the region but Environment Canada has reported that Arctic temperatures have been rising, and 2006 was the warmest year on record for that part of the Arctic.
Some arctic ponds have drained when the permafrost melted beneath them, these ponds sit above bedrock.
But Cape Herschel had existed for millennia — ice for 10 months of the year and liquid in July and August — in depressions in the bedrock, so the water could only have evaporated as temperatures rose, they believe.
Changes set in about a century ago, he said, with more mosses growing and shorter periods of ice, followed by lowering water levels and increasing salinity until some dried up completely. In addition to the ponds, the researchers also reported a drying of nearby wetlands.
"The ecological ramifications of these changes ... will cascade throughout the Arctic ecosystem. ... Lower water levels will have many indirect environmental effects, such as further concentration of pollutants," the researchers wrote. The ponds are the most common source of surface water in many polar areas, and part of the Arctic ecosystem. They provide habitat for waterfowl, drinking water for animals and homes for tiny invertebrates like shrimp, which are a food source for larger animals.
"It's really interesting to see how quickly it is happening. We could see this trend had started a while ago but at no time did we expect it to accelerate," said Douglas. In the 1980s they often needed to wear hip waders to make their way to the ponds, they noted, while by 2006 the same areas were dry enough to burn.
You May Also Like