Lake Superior hits warmest temp in 31 years of records

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Surface waters of Lake Superior recorded at three buoys across the lake this week reached their highest average temperature in the 31 years records have been kept.

The water temperature Tuesday hit 68.3 degrees at a time of year it should be about 55, topping the previous record of 68 degrees set during the strong El Nino summer of 1998.

The News Tribune first reported in July that the big lake was on a record warming pace, with August usually the warmest month of the year for Superior’s surface water.

Researchers Jay Austin and Steve Colman at the Large Lakes Observatory of the University of Minnesota Duluth have been predicting that the water would likely reach and pass the old record after a winter with little ice and an unusually warm spring.

Austin has been studying the data from the National Oceanic and Atmospheric Administration buoys in the lake and said he’s unsure as to how much higher the temperature could get.

“We’re basically in uncharted territory,” he said. “But we will anticipate seeing these warmer temps for the next week or more. I’d be astounded if (that high temperature) would be able to hold for another week.”

The big lake usually mixes, or turns over, when the surface waters hit 39 degrees Fahrenheit, when a shallow layer of warm water forms at the surface. That usually happens in mid-July. This year it happened a month earlier. That allowed the sun and warm air temperatures — Duluth is on pace to set a record for most 70 degree days in a row — to keep warming the big lake.

What warmer water temperatures mean for the lake is unknown.

It could mean a more fertile lake with more organisms that thrive in warmer conditions. And it could cause cascading biological effects to fish and other species that we can surmise but haven’t confirmed, according to Colman, co-researcher and director of the Large Lakes Observatory.

While less ice in winter leads to warmer water in the summer, warmer water in the summer does not seem to correlate to less ice in the winter, Austin said.

“It does not appear that what happens now is going to affect (how much ice will form on the lake) this winter,” he said. “It’s not something I completely understand. This is an active area of research.”

Research by Austin and Colman in 2007 showed that summer Lake Superior water temperatures were warming twice as fast as air temperatures over the past 30 years, based on NOAA buoy data. It is one of the most graphic temperature increases on the planet.

The warmer water not only means more swimmable water earlier this summer but also warmer breezes for people on shore. Now, even when winds are off the big lake, they’re more refreshingly cool than chillingly cold.

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