Arctic Lake Sediment Cores Show Recent Warming and Ecological Changes
21.10.2009 - Water & Oceans, Land & Geology, Flora & Fauna, Human Dimension, Other, Arctic
The results of a new study led by the University of Colorado at Boulder published in the Proceedings of the National Academy of Sciences on October 19th showed unprecedented biological and chemical changes in a sediment core retrieved from the bottom of an Arctic lake on the east coast of Baffin Island near Clyde River in Nunavut, Canada.
The team, which also consisted of researchers from the State University of New York at Buffalo, the University of Alberta, the University of Massachusetts and Queen's University in Kingston, Ontario, analyzed the extracted cores and found that biological and chemical changes occurring at a remote Arctic lake are unlike anything before it during the past 200,000 years and are likely caused by human-induced climate change. Although environmental changes have been linked to natural causes of climate change such as periodic and well understood wobbles of the Earth's orbit, the lake core sediments hold evidence that human activity such as greenhouse gas emissions has overridden a natural cooling cycle in the climate.
The team succeeded in reconstructing past climate conditions going back as far as 200,000 years using indicators such as algae or fossilized insects found in the lake sediment cores. The cores showed that several types of insects adapted to the cold were abundant at the lake before they began to decline abruptly around 1950, with two of them eventually disappearing completely. At the same time, a species of algae that had been relatively rare at the site began flourishing after the ice cover began to decline.
The sediment cores were the oldest ever retrieved from Arctic Canada and Greenland. Luckily the sediment was not eroded during periods when glaciers covered the lake, leaving a long sequence of sediment capturing the environmental conditions of two previous ice ages and three interglacial periods.
