CHEBOYGAN, Mich. (AP) — From the bridge of the Coast
Guard cutter Mackinaw, northern Lake Huron looks like a vast,
snow-covered field dotted with ice slabs as big as boulders — a
battleground for the icebreaker’s 58-member crew during one of the
roughest winters in memory.
It’s been so bitterly cold for so long
in the Upper Midwest that the Great Lakes are almost completely covered
with ice. The last time they came this close was in 1994, when 94
percent of the lakes’ surface was frozen.
As of Thursday, ice
cover extended across 88 percent, according to the federal government’s
Great Lakes Environmental Research Laboratory in Ann Arbor.
Sections
of the lakes, which hold nearly one-fifth of the freshwater on the
world’s surface, harden almost every winter. That freezing keeps the
Coast Guard’s fleet of nine icebreakers busy clearing paths for vessels
hauling essential cargo such as heating oil, salt and coal. But over the
past four decades, the average ice cover has receded 70 percent,
scientists say, probably in part because of climate change.
Still,
as this season shows, short-term weather patterns can trump multi-year
trends. Winter arrived early and with a vengeance and refuses to loosen
its grip.
"That arctic vortex came down, and the ice just kept going," said George Leshkevich, a physical
scientist with the federal lab.
The
deep freeze is more than a novelty. By limiting evaporation, it may
help replenish lake water levels — a process that began last year after a
record-breaking slump dating to the late 1990s. Also getting relief are
cities along the lakes that have been pummeled with lake-effect snow,
which happens when cold air masses suck up moisture from open waters and
dump it over land.
Buffalo, N.Y, got nearly 43 inches of snow in
January, but this month just 13 inches have fallen, a decline resulting
largely from the freeze-over of Lake Erie even though Lake Ontario has
remained largely open, said forecaster Jon Hitchcock of the National
Weather Service.
Heavy ice can also protect fish eggs from predators, and it has delighted photographers, ice anglers and
daredevil snowmobilers.
At
Apostle Islands National Lakeshore in Wisconsin, the rock-solid cover
has allowed around 35,000 visitors to trudge miles over Lake Superior to
explore caves featuring dazzling ice formations. It’s the first time in
five years the lake surface has been firm enough to allow passage.
With
no letup in the cold, the ice hasn’t experienced the usual
thaw-and-freeze cycle, so nature’s artistry is even more delicate and
beautiful, with needle-like hoarfrost crystals sprinkled across sheets
that dangle from cave ceilings like giant chandeliers.
"Seeing them like this is almost a once-in-a-lifetime experience," Superintendent Bob
Krumenaker said.
There’s
even an (apparently) tongue-in-cheek Facebook page inviting people to
join a convoy of snowmobiles, cars and other vehicles on a nearly
80-mile trek across Lake Michigan. Never mind that its waters remain
partly open and experts warn the ice can be dangerously unstable.
"If it freezes, and you miss this chance, when will it happen again?" the page says. "Feel
free to invite more folks!"
For
Coast Guard icebreaker teams, it’s all business. They’ve logged four
times more hours this season than the average for the same period in
recent years, said Kyle Niemi, spokesman for the agency’s Cleveland
district headquarters.
The 240-foot-long Mackinaw began its duties
Dec. 16 — several weeks earlier than usual — and worked nonstop until
Feb. 8, when traffic slowed enough to allow a break.
"As you can
imagine, the crew’s tired," Cmdr. Michael Davanzo said this week during a
tour of the ship in its home port of Cheboygan.
A 35-year Coast
Guard veteran who has spent 12 years on the lakes, Davanzo said this
winter is the toughest he’s experienced because the ice came so soon and
is so thick and widespread, and the weather has been constantly bitter.
The
Mackinaw, commissioned in 2006 to replace an older vessel with the same
name, is designed specifically for duty on the Great Lakes. It’s
propelled by two "Azipod" thrusters that can spin 360 degrees and fire
jets of water at adjacent ice, weakening it. Sometimes the crew will
drive the ship’s bow onto an ice sheet to crack it with sheer weight. Or
they’ll go backward, chopping up ice with the propeller blades.
When
the going gets tough, there’s the battering-ram option — hurling the
reinforced hull directly against walls of ice that can be several feet
thick.
The workload typically drops sharply after navigational
locks on the St. Marys River, the link between Lakes Superior and Huron,
close in mid-January and most large cargo haulers dock for winter. But
the ice was so thick this year that a number of freighters were still
struggling to complete final deliveries days later. Even now, demand for
road salt and heating oil in the Midwest is keeping some icebreakers
busy.
One day last month, the Mackinaw spent 16 grueling hours
helping a freighter squeeze through a narrow 3.5-mile section of the St.
Marys. As the Mackinaw attacks the ice, the engines roar and the ship
vibrates. The noise and motion are "like living in an earthquake 16
hours a day," Petty Officer 3rd Class Ryan Alderman said.
Davanzo
hopes for rain and warmer temperatures that would melt some ice before
the locks reopen in late March, when the Mackinaw will venture onto Lake
Superior and clear paths for iron ore and coal haulers.
"But if the weather stays like this," he said, "we could be breaking ice all the way to
the middle of May."
Despite
the inconvenience, there’s a silver lining for shippers. Since the
low-water period began in late 1990s, they’ve been forced to carry
lighter loads to avoid scraping bottom in shallow channels and harbors.
Heavy snow and rain in 2013 finally raised water levels.
Ice cover
blocks evaporation, the leading cause of low water. It also will keep
the lakes cooler for a longer time this year, delaying the onset of
heavy evaporation season, scientist John Lenters reported in a paper
last month, although the benefit is partially offset by stepped-up
evaporation shortly before the ice forms.
In Lake Superior,
snowbound Isle Royale National Park is home to a dwindling and inbred
wolf population that is usually trapped on the island. Biologists hope a
newcomer or two will venture to the park now that the lake is almost
entirely frozen over. The park’s first wolves are believed to have
crossed an ice bridge from Canada, 15 miles away, in the late 1940s.
There’s also a chance that one or more of the island’s wolves could grab the rare opportunity to escape.

"They
are inveterate travelers," veteran wolf expert Rolf Peterson said. "And
they don’t need a reason that would make sense to us."
___
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