Cal professor part of report that expresses alarm about warming lakes
Climate change is quickly warming lakes around the world, including Lake Erie, threatening freshwater supplies and aquatic ecosystems.
That’s the consensus of a new NASA and National Science Foundation-funded study of temperature readings for 235 lakes and reservoirs – more than half of the world’s freshwater supply – between 1985 and 2009.
Dr. Derek Gray, an assistant professor in California University of Pennsylvania’s Department of Biological and Environmental Sciences, was a key contributor to the study, which included more than 60 scientists from 15 countries and was announced recently at the American Geophysical Union in San Francisco.
Gray was a lead participant in the data analysis phase and one of four co-authors of a report slated for publication in the journal Geophysical Research Letters.
The study found, globally, lake temperatures are rising an average of 0.61 degrees Fahrenheit each decade, more rapidly than ocean or air temperatures.
The Great Lakes are no exception, and they are “warming pretty significantly,” said Gray.
Lake Superior is one of the world’s fastest-warming lakes, rising 2.09 degrees Fahrenheit a decade.
Lake Erie is rising at about 0.14 degrees Fahrenheit every 10 years.
“Lakes in the northern latitudes are warming the fastest. The ice is breaking up earlier every year, and once it’s gone, solar radiation heats the lake,” said Gray.
Gray said scientists are concerned about the impact warming lakes will have on fresh water.
“Fresh water is one of our most vital resources,” said Gray, who noted lakes are important sources of water for drinking, irrigation, energy and food production.
The study indicates as warming rates increase over the next century, algal blooms – the rapid and sudden growth of microscopic algae – will increase, which could have harmful effects on both water quality and aquatic life, including fish harvested for food.
“We worry about the ecological impact, and we’re worried that exotic, invasive species would do better in warmer water than fish that rely on cooler water temperatures,” said Gray.
Researchers forecast a 4 percent increase worldwide in lakes’ emission of methane, a powerful greenhouse gas implicated in global warming, over the next decade if these rates continue.
As lake water warms, evaporation increases and water levels decline, making less fresh water available for human use.
“This study shows that warming of lakes already has begun, and the lakes are warming faster than the ocean and air temperature, which was kind of a surprising result,” said Gray, who spent the past two years analyzing the data. “It’s been really cool working on this because I got to meet scientists from many different countries, and it was neat to get different perspectives and meet people who had been collecting data for decades. But it’s kind of unknown what the final impact will be. It’s kind of an open question as to what impact it will have.”
Gray grew up in Canada, where he received his undergraduate and graduate education. While working on his master’s degree at the University of Windsor, he conducted research aimed at finding ways to prevent the introduction of invasive species into the Great Lakes. His Ph.D. research at Queen’s University examined how small wilderness lakes on the eastern shore of Georgian Bay recovered after being damaged by acidification. Gray then moved to the state of California to conduct postdoctoral training at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara. His postdoctoral research examined the impacts of climate change on Lake Baikal, in Siberia.