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. 
 
 In this Feb. 5, 2014 photo photo provided by the U.S. Coast Guard a yardstick measures the thickness of some of the ice the crew of cutter Katmai Bay, background, battles during ice-breaking operations... (Associated Press) 
 
 The Coast Guard Cutter Biscayne Bay, a 140-foot ice-breaking tug, sails the waters near Chicago and toward the shores off Indiana, Feb. 12, 2014. The Biscayne Bay helped break ice on the southern part... (Associated Press) 
 
 In this Feb. 6, 2014 aerial photo is a view of Lake Huron looking south towards Port Huron, Mich., right, and Sarnia, Ont., left. This winter has been so bitterly cold for so long that the sprawling Great... (Associated Press) 
 
 In this Feb. 7, 2014 photo provided by the U.S. Coast Guard the icebreaker Katmai Bay escorts the lgo Steel with a load of road salt through the Straits of Mackinac. Sections of the lakes harden almost... (Associated Press) 
 
 In this Jan. 10, 2014 photo provided by the U.S. Coast Guard are Great Lakes freighters Arthur M. Anderson, left, and James R. Barker, seen from the icebreaker Mackinaw, on the St. Marys River, which... (Associated Press) 
 
 In this Feb. 12, 2014 photo provided by the U.S. Coast Guard the icebreaker Biscayne Bay passes Chicago's Navy Pier, left, as it through the ice covered waters of Lake Michigan on it's way to Indiana.... (Associated Press) 
 
 In this Feb. 2, 2014 photo people visit the caves at Apostle Islands National Lakeshore in northern Wisconsin, transformed into a dazzling display of ice sculptures by the arctic siege gripping the Upper... (Associated Press) 
 
 In this Dec. 26, 2013 photo provided by the U.S. Coast Guard the icebreaker Mackinaw maintains a shipping lane on the St. Marys River linking Lakes Superior and Huron. It’s been so bitterly cold for so... (Associated Press) 
 
 In this Feb. 11, 2014, Petty Officer 3rd Class Ryan Alderman studies instruments in the bridge of the cutter Mackinaw, which is docked in Cheboygan, Mich., after weeks of icebreaking duties on the upper... (Associated Press) 
 
 In this Jan. 9, 2014 photo provided by the U.S. Coast Guard a convoy of Great Lakes cargo ships line up to follow an icebreaker on the St. Marys River, which links Lakes Superior and Huron. As of Feb.... (Associated Press) 
 
 This Feb. 11, 2014 photo the pier and lighthouse at Lake Michigan’s Little Traverse Bay at Petoskey, Mich., is surrounded by thick ice. Nearly 88 percent of the Great Lakes’ surface area has frozen over... (Associated Press) 
 
 In this Feb. 2, 2014 photo people visit the caves at Apostle Islands National Lakeshore in northern Wisconsin, transformed into a dazzling display of ice sculptures by the arctic siege gripping the Upper... (Associated Press) 
 
 POOL PHOTO -- In this Feb. 11, 2014 aerial photo the Mackinac Bridge over the the Straits of Mackinac spans an ice cover that stretches into the horizon in Michigan. As of Feb. 13, the ice cover extended... (Associated Press) 
 
 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." 
 
 ___ 
 
 Follow John Flesher on Twitter at http://twitter.com/JohnFlesher . ||||| If this winter needed a theme song, it might be “Ice Ice Baby.” 
 
 The Great Lakes are on the cusp of a record for ice cover. 
 
 “In the last one to two weeks, we’ve seen rapid accumulations on Lakes Superior, Huron and Michigan,” said Jeff Andresen, an associate professor in Michigan State University’s geography department who also is the state climatologist. 
 
 The ice cover on the lakes increased from 79.7% to 88.4% just in the last week, putting the region close to the record of almost 95% set in February 1979, according to data compiled by the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory in Ann Arbor. 
 
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 The extensive ice cover has had some interesting and positive effects, like shutting off lake-effect snow, making it sunnier in parts of northern and western Michigan and limiting evaporation, which could help boost lake levels. 
 
 And the ice cover, Andresen said, could help delay the spring warm-up — good news for farmers as it helps keep certain crops, like fruit trees, dormant longer and less susceptible to freezing early in the growing season. 
 
 Andresen said that the winter of 2013-14 also is shaping up to be one of the five coldest in Michigan in recorded history, although it’s still early to say for certain. 
 
 “We haven’t seen many winters like this that are cold from beginning to end,” he said, noting that this is the fourth consecutive month that is colder than normal. “It has been an extraordinary winter, and the ice cover is a manifestation of that unusually cold winter.” 
 
 He cautioned that temperatures forecast in the 40s next week could hurt the chances to break a record for ice cover. 
 
 “Given the warmer weather next week, it may not be in the cards, but it’s way, way above normal,” Andresen said. 
 
 Still, he cautioned not to “put the snow blower away just yet” because some forecasts predict that extremely cold weather could return later in the season. 
 
 George Lessens, chief meteorologist at WZZM-TV (Channel 13) in Grand Rapids, agreed that the ice cover on the Great Lakes is substantial, but he doubts the region will hit a record. 
 
 “We could see the lakes getting close to that record if we had another week to 10 days (of below-freezing temperatures), but we’re going to go into the 40s next week. That’s really going to put the brakes on it,” he said. 
 
 If the lakes fail to beat the record, we can blame Lake Ontario. 
 
 “Lake Ontario is still quite a bit uncovered. They’re holding everyone back,” Lessens said. 
 
 Lake Ontario’s depth and the churning caused by Niagara Falls mean that it needs long stretches of exceptionally cold weather to freeze. It had ice cover of just over 40% Thursday. Other lakes are almost completely covered: Superior, 93.6%; Huron, 95%, and Erie, 95.7%. Michigan was at 81%. 
 
 The extensive lake ice provided a backdrop for U.S. Rep. Candice Miller, a Harrison Township Republican, on Thursday as she traveled aboard the U.S. Coast Guard’s 225-foot icebreaker, the Hollyhock, from Port Huron. 
 
 “I was interested to see up close the vast amount of ice blanketing Lake Huron and extremely impressed with the skill, dedication and persistence demonstrated by the crew of the Hollyhock as they cut through the ice,” Miller said in a news release. 
 
 “This winter’s brutally cold conditions create even greater challenges as they work to stay ahead of the ice and prepare for ice jams during the spring thaw.”
– It's been so cold for such a long time in the Great Lakes region that the lakes are now almost completely covered with ice for the first time in 20 years. Ice cover has now reached 88% across the five lakes, the most since 1994, when 94% of their surface was frozen, the AP finds. Average ice cover has receded around 70% over the last four decades, so this year's deep freeze will do much to replenish lake water levels by limiting evaporation. "It has been an extraordinary winter, and the ice cover is a manifestation of that unusually cold winter," Michigan's state climatologist tells the Detroit Free Press. The ice cover record could be broken by next week if the current rate of increase continues, a meteorologist says, though Lake Ontario is "holding everyone back" with ice cover of just 40%, caused by its depth and the churn of Niagara Falls. On Lake Superior, which is almost 94% frozen over, the Apostle Island Ice Caves can be reached on foot for the first time in years.