One change Silet is worried about is the volatility of the lake levels.
“When you start doing these really drastic up and down water levels, you start seeing a lot more of those negative impacts potentially to the hatching of those eggs,” he said.
That’s because whitefish spawn in rocky coastal areas. When water levels drop, spawning grounds can be disrupted. During the winter, ice can scour the spawning grounds and damage eggs.
“If the projections are what they are appearing for climate change, we may be going into a sort of bad situation with the ability for whitefish eggs or even lake trout eggs to be able to survive,” Silet said.
Big storms on the big lake
Lake Superior is not just warming; it’s warming faster than its surroundings.
Jay Austin and a colleague published a study on Lake Superior warming about 15 years ago. Austin is a faculty member at the Large Lakes Observatory at the University of Minnesota, Duluth.
“We looked at summer surface water temperature increasing — and at the time it was only 25 years but the message remains today with an extra 15 years of data — was faster than the change in air temperature,” he said.
Climate change is affecting Lake Superior in some volatile ways. Its surface temperature has been going up, but with wild fluctuations. The average wind speeds have been increasing 5 percent each decade since 1980.
And Superior has been pounded by three 500-year to one 1,000-year storm events in the past eight years.
“If it’s not climate change, what is it?” asked Peter Annin, who has documented the effects of climate change in his recently revised book Great Lakes Water Wars.
“I mean, that we have the largest lake in the world by surface area is not just seeing one extreme event, it’s seeing a series of scientifically documented extreme events that are creating a pattern that is changing the relationship that human beings are having with the Great Lakes that they love,” he said.
The ups and downs of the Great Lakes
The effects people are talking about now are the historically high lake levels of the Great Lakes. But it wasn’t that long ago that people were concerned about historically low water levels.
The two most significant things that affect the water levels of the lakes are precipitation and evaporation.
“In 1998, Lake Superior’s temperature went up about two degrees Celsius (3.6 Fahrenheit) and it stayed there,” said Drew Gronewold, hydrologist at the University of Michigan’s School of Environment and Sustainability.
It stayed warm for more than 15 years. Gronewold said typically there’s more of a balance between precipitation and evaporation, but during that period evaporation was well…