A study of 235 lakes representing half of the world’s freshwater supply found that climate change is warming lakes more rapidly than the land or ocean, said research presented at the American Geophysical Union meeting this week. Researchers looking at records over the past 25 years found that lakes warmed by an average of 0.61 degrees F per decade.
The effects can be profound, says a Washington State University release. Algal blooms, which consume oxygen, are projected to increase by 20 percent over the next century as warming continues. Blooms toxic to fish and animals would increase by 5 percent. Emissions of the powerful greenhouse gas methane are projected to increase by 4 percent during the coming decade.
“These results suggest that large changes in our lakes are not only unavoidable, but are probably already happening,” said Catherine O’Reilly, associate professor of geology at Illinois State University and the lead author of the study. Previous work by O’Reilly indicated that rising temperatures mean lower productivity in lakes. A co-author of the report, Stephanie Hampton of Washington State University, said lake water is used in public water supplies, manufacturing, crop irrigation and energy production. In the developing world, freshwater fish are an important source of protein.
Also at the AGU meeting, a study by Ohio State U researchers said the number of toxic algal blooms in Lake Erie will likely double over the next century. A toxic bloom cut off the supply of drinking water for Toledo in 2014. Ohio, Michigan and Ontario agreed to reduce phosphorus runoff by 40 percent over a decade but the effect may be overwhelmed by the effects of climate change — higher summer temperatures and heavier spring rainfall. “We can reduce phosphorus by 40 percent, but the algae won’t suffer as much as you might hope,” said Noel Aloysius, a post-doctoral researcher who was part of the research team.