Lake Superior Ice Hits 50-Year Record Low, Why?
Where's the ice? After picking up 83" of snow and counting you'd think we'd have more ice on Lake Superior. But according to NOAA, satellite imagery shows that less than 5% of Superior is covered in lake ice as of February 15. That is the lowest number since records first started in 1973.
We've seen plenty of snow, but it hasn't been that cold this winter, at least not yet. Your heating bills have been less, in fact heating degree data from the Duluth office of the National Weather Service shows that we've saved about 7% on heating bills for our homes and businesses so far this winter season. Another marker for how cold it's been? The quantity and quality of lake ice, including the greatest freshwater lake of all.
According to NOAA CoastWatch only 6.6% of the entire Great Lakes basin is ice-covered as of mid-February, which is the lowest amount of ice on the Great Lakes since 1973. Prevailing winds aloft have blown mostly from the Pacific since early January, not the Arctic, and that has had a significant impact on the quantity and quality of lake ice.
This graphic provides some perspective on Lake Superior. Based on averages over the last 50 years roughly 37% of the lake should be ice-covered by now, with "peak ice" coming in early March. Instead we are holding under 5% ice coverage on Lake Superior as of February 15.
Tracking the Trends
Diminishing lake ice on all Minnesota lakes is a trend, not a fluke. The warming signal is most pronounced during the winter months. Put simply, winter arrives later and spring comes earlier (most years) and that is having an impact on lake ice, statewide. Average ice duration has decreased by 10-14 days over the last 50s years and 16-21 days since the 1920s. Check out the trends yourself with the public domain data set from Tableau.
No, it's not your imagination. We are seeing more open water on Superior during the mid and late winter months over time. There will always be icy exceptions, but if you step back and look at the big picture trends, there's little question that winter lake ice is, in fact, in decline all across the Northland.
At the rate we're going, 2023 may wind up being Exhibit A.