An ice fisher waits for a catch. Douglas E. Walker/Corbis

Without a frozen body of water, ice fishing becomes pretty much impossible. Ice fishers need a thick crust of ice over a lake to allow them to safely venture out on the frozen water. But as the temperatures rise, lakes stay liquid longer. For example, the average number of days of ice cover on two Wisconsin lakes has dropped by 29-35 days over the past 150 years, according to data collected at the University of Wisconsin – Madison.

Increasingly during the past decade, ice fishers have been forced to stay closer to shore or give up on their sport entirely. In 2002, the Canadian Ice Fishing Championship was cancelled because of insufficient ice thickness. And 36 ice fishers probably wished they had skipped their angling excursion when their cars ended up in Lake Winnebago in 2012, reported the Milwaukee Journal Sentinel. The ice where they had parked gave way during a sturgeon ice fishing tournament.

A lack of an ice covering also allows more evaporation from a lake during the winter, which can harm fish nesting sites. Ice cover also helps regulate lake temperatures.

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Wayne Gretzky, of the Edmonton Oilers, controls the puck during a game at Nassau Coliseum on Long Island in New York in 1981.Bettmann/CORBIS

Climate change could score a wicked slap shot against hockey. Like ice fishing, outdoor hockey rinks depend on long periods of cold weather to keep the ice solid.

The amount of time that temperatures stayed low enough to keep ice rinks solid decreased significantly between 1951 and 2005 in Canada, according to a study published in Environmental Research Letters. The researcher suggests that by the middle of this century, parts of southwestern Canada may completely loose their outdoor ice rink season.

Wayne Gretzky honed his hockey skills on an impromptu backyard hockey rink created when his parents flooded their back yard, noted the study authors. Future hockey stars may not get that experience.

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A woman carries skis at sunrise in mountains of Vail, Colorado.Joe Morahan/Corbis

Skiing without snow makes as much sense as hockey without ice. Numerous studies suggest that many ski resorts' futures are melting away. Many skiing areas in the northeastern United States may fail by the middle of this century, warned an analysis of 103 skiing areas published in the journal Tourism Management.

When nature can't provide the snow, technology can step in with snow-making machines. The need for snow-making equipment at ski resorts may increase by as much as 144 percent in southern Ontario, Canada by the 2020s, according to a study in Climate Research. Small, family-owned ski lodges may suffer the most, since they don't have money to invest in expensive snow-making machines.

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Snowmobiling in Togwotee Pass region of the Bridger-Teton and Shoshone National Forests near Moran, Wyoming.Richard Hamilton Smith/Corbis

What's worse than skiing on mud? How about snowmobiling on rocks? Snowmobiles may become relics as heavy snowfalls retreat to the far north. Unlike skiing, snow-making machines won't be capable of bailing out snowmobiling. Blasting across miles of snowpack requires more snow than any machine can realistically produce.

Since snow-making can't help, snowmobiling season may drop to less than 50 days in many regions, warned research published in Mitigation and Adaptation Strategies for Global Change.

Besides killing snowmobile sports, less snow build-up over the winter results in lower flows in streams and rivers in the spring. Many species evolved to depend on the rush of spring waters. Humans, too, may go thirsty, since many cities, including Los Angeles, draw water from melting snow in distant mountains.

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A flock of black and white snow geese takes to the air at New Mexico's Bosque Del Apache Wildlife Refuge.Darrell Gulin/Corbis

Though the flurry of wings can be dizzying at times - usually birdwatching is on the opposite end of the extreme sports spectrum from snowmobiling. One of the most tranquil of hobbies, birdwatching may also suffer as winters warm. Birdwatchers now have to alter the times they head out to catch glimpses of their feathered friends.

In Europe, birds that migrate to Sub-Saharan Africa leave earlier than they did 42 years ago, according to research in the Proceedings of the Royal Society B. Many birds that winter in North Africa now migrate later in the year.

Birds can suffer as the winter ends sooner. In some cases, the onset of spring now occurs before migratory birds have arrived and set up nests. This means missing the spring boom of insects, endangering new chicks' diets.

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Maple farm staff tap the sweet sap of maple trees in the maple farm around Sucrerie de la Montagne, a 35-year-old sugar shack, in Rigaud, Quebec, Canada on March 6, 2013.ZHANG DACHENG/Corbis

Pancakes slathered in genuine maple syrup make a perfect breakfast to fuel a day of any winter activity from ice fishing to snowmobiling. But warm winters even threaten breakfast.

Sugar maple trees require a long, frigid winter to produce the sap that becomes maple syrup. The trees need weeks of subzero temperatures during which the sap in their branches freezes. The freeze reduces the pressure in the trees' sap-conducting tubes, which sucks up more sap from the roots, reported Treehugger. Then in spring, as the sap begins to flow, the tree can be tapped for its tasty bounty.

A study in Climatic Change documented that as the winters warmed between 1980 and 2006, the traditional tree-tapping season shrunk by up to 14 days in some areas. But hope remains. Starting the tree-tapping season earlier may allow syrup producers to make up those lost days.

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Mature Fuji apples on a tree in California have a coating of a plant surface protectant that reflects infrared and ultraviolet radiation to prevent sunburn and heat stress.Steve Goossen/Corbis

Along with maple syrup, warming winters have changed another sweet treat from trees. Apple trees need a cold, dormant season. When winters end sooner, apple trees produce softer, sweeter fruit.

Forty years of apple tree data from Japan showed a trend toward earlier flowering and fruit production in Fuji apples. By harvest time, that fruit was higher in sugar, yet lower in acid, according to research published in Nature's Scientific Reports.

A study in the International Journal of Biometeorology found that apple trees now start flowering two to eight days sooner in the northeastern United States. Many other plants also sprout and bloom earlier in the year now, which can be problematic if pollinators haven't adapted their life cycles to catch the early spring.

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A couple kisses over a baby carriage. Frank May/Corbis

Every year, medical records show a mini-baby boom in late summer and early fall, which means parents conceived those babies in November and December. Besides the romance of snuggling by the fire, winter may have a direct biological effect on baby-making.

Sperm survive best in cooler temperatures, which is one of the reasons many species' testicles dangle outside the body. Even a small rise in temperature can decrease sperm counts in humans and hot summers may be responsible for decreasing sperm counts in the summer, suggested a study published in Advances in Experimental Medicine and Biology. After the temperature drops, sperm counts rise and the potential for pregnancy increases.

In short, as winters warm up, sperm could suffer. Plus, there will be less reason to stay under the bed covers during a warm winter or go for a romantic walk in a winter wonderland.

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A large bull moose walks thru the fall foliage in Denali National Park and Preserve, Alaska.Doug Lindstrand/Design Pics/Corbis

A long, frigid winter kills many dormant insects and eggs. However, warm winters allow pests to survive into the spring to bug game animals, such as deer and moose. Hunters may find their quarry suffering as the winter season mellows.

“Cold temperatures are a barrier that limits the spread of potentially devastating outbreaks of disease in our northern big game herds,” said Jim deVos, retired chief of research for the Arizona Game and Fish Department, on the website Seasonsend. “If that barrier comes down, big game will die from those diseases at a steadily increasing rate.”

Moose in the Rocky Mountains, for example, now harbor dangerous numbers of ticks. The insects survive over mild winters, then strike the moose even harder after the ticks' eggs hatch in spring. The infested moose rub their skin raw trying to find relief from as many as 150,000 individual ticks. Moose may eventually die of complications from the trauma.

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The crescent moon is seen behind an ice sculpture during ice and snow sculptures festival at the Eight Lakes Park-Resort outside Almaty, Kazakhstan, on Jan. 14, 2013.SHAMIL ZHUMATOV/Reuters/Corbis

The Harbin International Ice and Snow Sculpture Festival in northern China creates a city from ice illuminated with brilliant lights. At the Quebec City Winter Carnival, builders create a palace from ice. In Sapporo, Japan, the Snow Festival features sculptures and buildings made from solid water.

Massive ice festivals, along with smaller regional winter fairs, all face threats from warming winters. For example, in Ottawa, the Winterlude festival melted to only seven days during the winter of 2001-02.