Entire lakes feel effects of climate warming

Climate warming brought on in part by human activities is producing major ecological changes in remote arctic lakes at an alarming rate, according to new University of Alberta research–the first study to show a whole lake biological response to warming in these waters. Even in the most remote, pristine parts of the earth–far from the direct influence of human activities–changes are occurring in entire ecosystems, says Dr. Neal Michelutti, a post-doctoral fellow in the U of A’s Faculty of Science.

“We study these lakes as models of global change,” said Michelutti. “If you think of these lakes as sentinels of change they are telling us that recent warming, attributable in part to human activities, has already begun and the result is a dramatic change in the way that entire ecosystems function.”

Michelutti and his research team, including his supervisor, Dr. Alexander Wolfe, from the U of A’s Department of Earth and Atmospheric Sciences, used an innovative technique developed at the U of A called reflectance spectroscopy. It allowed them to “see” in wavelengths what the human eye can’t and to learn about the chemical composition of the sediment in six lakes on Baffin Island. In this case, they found major increases in the concentration of chlorophyll a–a good indicator of overall ecosystem production. The research is published in the current issue of Geophysical Research Letters.

What is alarming about these findings is the magnitude and the timing of the changes, says Michelutti. “For the last several thousand years, chlorophyll a concentrations in our study lakes were very low and showed little variability–until approximately 150 years ago when chlorophyll a increased rapidly and reached unprecedented levels. The timing of these changes corresponds to the start of the Industrial Revolution and when humans first started having a major impact on global atmospheric chemistry,” said Michelutti.

“Increased aquatic production due to climate warming has been predicted for many years, but until now has never been demonstrated,” he said. “So, we were not totally surprised by our findings; however, the rate and magnitude of the changes that we recorded are definitely alarming, especially when taken in the context of the last several thousand years of variation.”