News

The melting of Minnesota

Bill McAuliffe, Star Tribune
March 20th, 2006

 

OSAKIS, MINN. -- Norman Clyde is puzzled by the sight of the fishing shack still for sale in front of his bait shop. Last year, he sold six on the same spot. This year, he can't sell one.

 

Granted, Clyde was competing with the warmest January in at least a century. Out on Lake Osakis, a popular fishing spot in central Minnesota, there were half the usual number of shacks, and sheets of water lay over thin ice. In town, despite the completion of a new trail, snowmobile traffic was scant.

 

Clyde can live with one odd month. But he and others have come to suspect something larger than an extended January thaw is at work. Across Minnesota, there's a growing conviction that what's happening on the lakes, in the woods and in back yards is linked to warming patterns evident around the world.

 

"We keep thinking every year when something like that happens, it's an anomaly," Clyde said. "But it's been getting stranger and stranger every year."

 

Clyde said it doesn't surprise him that state climatologists, using almost 140 years of data, have determined that Lake Osakis now breaks open in the spring, on average, a week earlier than it did a century ago.

 

Kim Lucas, a veteran of 40 winters fishing on the ice, said the same thing.

 

"We don't have that old-fashioned winter anymore, when things really got cold," he said. "Something has turned."

 

In northwest Minnesota, U.S. Fish and Wildlife Service scientists cite warming as a reason why a moose herd that 20 years ago numbered nearly 4,000 may soon disappear. In the Boundary Waters Canoe Area Wilderness, foresters are noticing that maples and oaks more suited to warmer climates are taking hold. Near St. Peter, naturalist Jim Gilbert says lilacs are blooming in the spring two to three weeks earlier than when he first began watching them in 1967. In Dakota County, parks officials no longer schedule skiing and snowshoeing events for December and January, for lack of snow.

 

Those examples are reinforced by a pile of meteorological data showing that the state has been getting warmer and wetter for some time. No one's panicking, but when winter itself is under siege, climate change in Minnesota becomes a question of identity.

 

Greta Petrich, who reports the Lake Osakis ice-out dates to the Department of Natural Resources, said local dealers are switching from selling snowmobiles to selling all-terrain vehicles. "Change or die," she said.

 

Brian Bahn, who works for Midwest Mountaineering in Minneapolis, said recently that he finds it "hard to look somebody in the face and sell them snowshoes."

 

The Minnesota Department of Tourism, responding to the recurring mild winters, produced a video promotion this season that for the first time features indoor activities, not just ways to enjoy snow and ice. The spots show an actor in a bear suit ice fishing and snowmobiling, but also browsing in an art gallery and making moves on a dance floor.

 

Concerns about extreme heat

 

In the Twin Cities, concerns about climate change in the summer, too, have prompted government, social service and health agencies to develop a hot weather emergency response plan. Rescue workers and those who work with the elderly would check on vulnerable people during heat waves.

 

"I've lived here since 1982, and when the trees start re-budding in November and the winters are lame like they have been, and each summer it seems the heat comes earlier and stays longer. ... I just think it's unfortunate we have to think extreme heat could have devastating consequences on people's health in Minnesota," said Pam Marshall, executive director of the Energy Cents Coalition, which helped develop the heat-wave emergency program. "But it's creeping north."

 

What's driving the changes?

 

The warming of the Earth is widely attributed to three things: natural, long-term climate variation; alterations to the landscape such as spreading cities and forest clearing, and a buildup of heat-trapping gases -- primarily carbon dioxide, methane and water vapor, known as "greenhouse gases" -- in the atmosphere.

 

It's the carbon dioxide (CO2) buildup that gets most of the attention, because it's linked to the burning of fossil fuels for electricity, heating and transportation. The Intergovernmental Panel on Climate Change, an international group of scientists commissioned by the United Nations, concluded that CO2 in the atmosphere has increased 30 percent increase since industrialization took hold in the mid-19th century.

 

The group, as well as the National Academy of Sciences, attributes that buildup to human activities.

 

In Minnesota, emissions of CO2 rose at four times the global rate, and 28 percent overall, from 1990 to 2004, according to the Minnesota Pollution Control Agency.

 

The U.S. Environmental Protection Agency cautions against drawing conclusions about climate outcomes in specific regions. President Bush also contends that uncertainties about the direction of climate change still exist. But he has said he supports curbing greenhouse gas emissions with new technologies that avoid economic disruption.

 

The causes and effects of the warming so far have been most dramatic in the Northern Hemisphere, because it has a higher proportion of both people and land -- which reflects heat, rather than absorbing it. And places far from oceans, such as Minnesota, are thought to be positioned for some of the most extreme changes.

 

At high latitudes and altitudes around the world, polar ice and mountain glaciers are melting and retreating at unprecedented rates. In Alaska, warming ground temperatures are thawing what had been permanently frozen soil, opening sinkholes, shrinking lakes and toppling trees and houses.

 

Meanwhile, Minnesota's annual average temperatures have been rising faster than the rest of the globe's -- some say twice as fast. The state Office of Climatology has calculated the rise at 1.8 degrees Fahrenheit since 1894. That's four times the variation the globe saw over the previous three to five centuries.

 

A study of the moose decline in northwest Minnesota found that between 1960 and 2001, temperatures in the area increased 12 degrees and winter and 4 degrees in summer. Climate change research predicts that global temperatures could rise between 2 and 10 degrees or more this century.

 

Shorter ice seasons could change the character of Minnesota lakes. With more time for evaporation, water levels could drop. Warmer lakes could release trapped pollutants and create metabolic problems for cold water fish, including Minnesota's favorites -- walleye, northern pike and trout, said Dr. Lucinda Johnson, associate director of the Natural Resources Research Institute at the University of Minnesota Duluth.

 

Next January, of course, could bring record cold. But Minnesota has been warming in both the short and long runs. For the Twin Cities, four of the five warmest winters since 1891 have occurred in the past 24 seasons. Four of the nine warmest have happened over the last nine winters, including this one.

 

According to University of Minnesota Extension meteorologist and climatologist Mark Seeley, the recent trends have been marked by warm winters, warm summer nights and high dew points. Elevated dew points -- a measure for human discomfort that also reflects plant vitality -- have increased in frequency and duration over the past 20 years. Dew points last July in Minnesota, Seeley noted, resembled those commonly recorded in Bombay, India.

 

Average annual precipitation -- often overlooked in discussions about climate changes -- has increased even more sharply than temperatures across Minnesota. Because of its connection to increased water vapor in the atmosphere, elevated precipitation is one of the central predictions in many global warming studies.

 

Hard times for a moose herd

 

Apart from the weather data, the moose decline in northwest Minnesota and the changing forest in the Boundary Waters are some of the most tangible evidence researchers have attributed to the warming climate.

The once healthy northwestern herd of moose has dwindled to fewer than 250, federal researchers have found. They tracked the animals with radio collars and determined that a number of ailments, including parasites possibly spread by deer, were killing the animals.

 

But a 2004 report on the moose decline also noticed an increase in mortality following hot summers, and deduced that the moose were weakened by having to use up energy keeping cool.

 

"The study concluded that climactic changes combined with increases in deer numbers and parasite transmission rates may have rendered northwest Minnesota inhospitable to moose," the report said.

 

Seeding an oak savannah?

 

On another front, Lee Frelich, director of the Center for Hardwood Ecology at the University of Minnesota, first detected the growth of red oak and red maple seedlings along the Canadian border in 1992.

 

While some climate scientists have predicted that the northern pine and birch forest could vanish altogether, Frelich said the red oak and red maple could replace it if the warming climate trend includes enough moisture. If the climate trend goes warm and dry, he said, the area could come to resemble oak savannah -- grassy prairie with intermittent stands of oak trees.

Seeley, the University of Minnesota climatologist, said he objects to fixatingon whether humans are completely to blame for warming. That distracts from discussions on what to do about it, he said.

 

"Scientific nitpicking disguises the fact that our vulnerability is not going away," Seeley told a group of farmers in southern Minnesota this month. "That vulnerability is almost a national agenda item. It's of more economic consequence than ever."

Polar explorer Will Steger and the advocacy group Minnesotans for an Energy Efficient Economy argue that Minnesota could benefit from trying to blunt global warming. They say moving away from fossil fuels could provide a significant boost to the state's wind and biomass energy industries.

 

The National Academy of Sciences, and Minnesota climate scientists such as Seeley, also say a warmer climate could bring benefits: lower heating costs and energy use, increased yields for some farmers and more time for summer recreation. Some evidence also suggests increased CO2 may actually enhance some plant life, trees in particular.

 

For places that thrive on recreation in ice and snow, however, the winter warmth isn't welcome. Last year, Lake Osakis shed its wintry armor on April 8, eight days ahead of the April 16 average.

 

Earlier this month, anglers were driving full-size pickup trucks onto the lake. They still needed to drill through 2 feet of ice to find sunfish and crappies. But last week, Petrich noticed slush on the surface of Lake Osakis. After an inspection Friday, she predicted it will be gone on April 8 once again.

 

For Kim Lucas and the few other anglers out fishing on the lake this time of year, the warming is bringing other changes. He had a baseball cap on -- not a winter hat -- out there one day this month. And they all expect to be moving to other lakes before long, heading farther north in search of a receding winter.