CHICAGO - The Coast Guard icebreakers near Duluth, Minn., are out weeks early.
Single-digit temperatures have nearly solidified parts of Lake Superior, and slowed the multibillion-dollar shipping business there and in the other Great Lakes.
This week 13 percent of Lake Michigan is covered by ice that was nowhere to be seen this time last year.
Sailing around Chicago's ice-clogged Burnham Harbor is like being on a polar expedition.
The city of Chicago's ice-breaking tugboat called the Commissioner is out on the water three weeks earlier than usual because serious ice is already forming here on the lakefront.
A path through the ice is essential for the shipping industry in the Great Lakes, which can move 15 percent to 20 percent of its annual total cargo during the ice season.
"The concern for a lot of the commercial shippers is they just simply can't get their boats in and out to transfer goods," said Phillip Willink, a research biologist at the Shedd Aquarium.
But, as the Commissioner plied -- or plowed -- the harbor to keep the ice from setting, he said the ice can benefit the lake, which had been hurt by years of low precipitation.
"The ice acts as a blanket and
sort of traps the water in the lake, preventing it from evaporating away, so the ice cover actually is helping to raise lake levels," he said.
And that blanket is likely to get thicker in the coming days, with highs in the teens on Monday -- when the real winter will be just getting started.