The Great Lakes hold 20% of the world鈥檚 surface fresh water and supply drinking water for more than 48 million people. This vital resource is threatened by harmful algae blooms that damage the freshwater ecosystem. Not all algae are harmful and identifying toxic ones (such as cyanobacteria) apart from other algae can be challenging. Joseph D. Ortiz, PhD, professor in the Department of Geology (soon to be the Department of Earth Sciences), developed a methodology using satellite remote sensing to identify different strains of algae in Lake Erie.
鈥淭he blooms in Lake Erie are predominantly driven by cyanobacteria,鈥 Ortiz says. 鈥淐yanobacteria are among the most ancient of living organisms on the planet. They date back billions of years and thrive in warm waters that have a high nutrient content.鈥
Those conditions exist in the western basin of Lake Erie. High amounts of nutrient runoff from agricultural fields result in perennial algae blooms. Differentiating among the potentially toxic algae provides essential information for public health decisions regarding water safety.
鈥淚n the Midwest, we鈥檙e seeing future predictions for wetter conditions for our environment,鈥 Ortiz says. 鈥淢ore rain will carry more nutrients, more fertilizer from farms into streams and creeks and eventually the rivers that feed into the lake. If climate change is going to make the environment wetter, we can expect that one of the potential consequences of climate change in our area will be worse harmful algae blooms.鈥
Graduate student Israel Olaoye modeled the impacts of urbanization and climate change on the area鈥檚 water quality in a study at Old Woman Creek, which is west of Cleveland. Although only a modest increase in urbanization is predicted for the region through 2100鈥攁bout 4%鈥攖he projected climate-related increase in precipitation would result in much higher nutrient runoff.
鈥淚f climate change is going to make the environment wetter, we can expect that one of the potential consequences of climate change in our area will be worse harmful algae blooms.鈥
鈥淥ur best estimates tell us that we need to drop the amount of nutrients getting into the lake by about 40% in order to get these harmful algae blooms to a point where they鈥檙e manageable,鈥 Ortiz says. 鈥淎nd that鈥檚 with the current precipitation. If we go a few decades into the future, with more CO2 in the atmosphere and higher precipitation rates, the amount of nutrients flowing into the basin is going to increase.鈥
Mitigation efforts to reduce nutrient runoff include planting vegetation along the riverbanks rather than farming up to the water鈥檚 edge. The forest strips that develop along the banks also help stabilize the soil and reduce erosion.
鈥淢any of the climate change issues we鈥檙e facing are having increasingly negative impacts not only on the environment but on society, particularly among the most vulnerable populations such as Indigenous communities or subsistence farming,鈥 Ortiz says. 鈥淭hat鈥檚 a real challenge because we鈥檙e seeing negative impacts occurring faster than previously anticipated. But there鈥檚 also opportunity. Every bit of emissions we reduce is one less tenth of a degree of global warming that will help mitigate potential problems coming down the pipeline.鈥
Read an co-written by Joseph D. Ortiz, PhD, that was republished by the Pulitzer Center as part of the series 鈥淐limate Change and Great Lake Cities.鈥
Learn more about the Department of Geology/Earth Sciences.