In late October, the National Oceanic and Atmospheric Administration (NOAA) reported that Lake Superior’s water temperatures were nearly three degrees Celsius above the long-term average. On October 20, the typical temperature for Lake Superior is 8.8 degrees Celsius, but this year, the surface temperature measured 11.6 degrees Celsius, marking the second-highest recorded temperature for that date. The warmest temperature ever recorded on October 20 was in 2021.
Unusually mild fall weather in northwestern Ontario this year has made October feel more like August, breaking several daytime temperature records by up to nine degrees Celsius. This unseasonably warm weather is contributing to Lake Superior maintaining a relatively warm temperature for this time of year, continuing a trend that impacts underwater ecosystems and coastal weather patterns.
According to Jay Austin, a physical oceanography professor at the University of Minnesota Duluth, the warm air temperatures significantly influence Lake Superior’s temperature. Austin mentioned that warm air temperatures result in a slower cooling rate for the lake. Over the past four decades, water temperature data collected from instrument and satellite readings across the Great Lakes show a gradual increase in Lake Superior’s temperatures.
Austin emphasized that above-average water temperatures can affect ecosystems, potentially leading to the growth of algae blooms. Lake Superior has been identified as one of the fastest-warming lakes globally, with research indicating that earlier spring ice melt contributes to longer lake stratification periods and increased solar radiation exposure, leading to rising summer surface temperatures.
Margueritte Xenopoulos, a professor at Trent University and Canada Research Chair in Global Change of Freshwater Ecosystems, along with her research team, is advocating for increased winter scientific research on the Great Lakes to better understand future trends. Xenopoulos highlighted the importance of predicting and forecasting potential risks, particularly in terms of nutrient runoff into the Great Lakes, which could impact drinking water safety for the millions of people living around the lakes. This enhanced understanding of environmental changes will assist communities in adapting to climate shifts and mitigating negative consequences around Lake Superior and its neighboring areas.
