Earth’s temperatures have warmed by an average 1 degree Celsius (1.8 degrees Fahrenheit) over the last century — enough to cause extreme temperatures, heavy rains and droughts in parts of the globe.
Some places, including Northwestern Minnesota, have seen average temperature increases more than double that, according to an analysis published this month by the Washington Post.
In Kittson and Roseau counties, the average annual temperature has increased 2.4 degrees Celsius (4.3 degrees Fahrenheit) over the last century. That’s among the biggest increases seen in the U.S., and experts say is already taking a toll on some of the plants and animals in the aspen parklands and prairies of Minnesota’s northwest corner.
Warming temps are caused by different things in different regions. In Minnesota, it’s the fact that it’s often so cold here that makes us susceptible to fast-rising temperatures, said Kenneth Blumenfeld, senior climatologist at the Minnesota State Climatology Office.
Any time the sun’s out, some of the sunlight that hits the Earth turns into heat. Greenhouse gases like methane, nitrous oxide and carbon dioxide, emitted by everything from cows to cars, trap that heat in the earth’s atmosphere, insulating the planet like a big wool sweater.
It’s when it’s supposed to be cold that the effects of this insulation are most noticeable.
“You see the effect, generally, most strongly in areas that have longer winters and longer nights, and in Minnesota, that’s true it the far north part of the states. That’s where we have longest nights [and some of the longest winters],” he said.
Most of the increase in average annual temperature Minnesota sees happens in the winter — particularly in the parts of Minnesota that get coldest in winter. Likewise, Sunbelt spots that never get the chance to cool down like Minnesota does are seeing a far smaller increases in annual average temperatures.
“Those greenhouse gases, they don’t work to make the sun hotter or anything like that. What they instead do is they prevent the earth from cooling down,” Blumenfeld said.
The Washington Post’s analysis is limited to the United States, but the greenhouse gas-driven hotspots don’t stop at the border.
“If we were to expand the map and show Canada, you would see much stronger [increases],” Blumenfeld said. “Almost like what you saw in Roseau and Kittson counties is kind of the beginning, as you go northward.”
Weather-wise, warming temperatures cause stronger hurricanes and tropical storms in parts of the world. In Minnesota, it’s tough to scientifically tie warmer temps to heavy winds, tornadoes or other characteristics of extreme storms here.
“Global temperatures have risen and the oceans are warmer, but when you get up here, where our extreme weather events aren’t driven specifically by heat, they’re driven by temperature contrast and winds aloft or other things that have secondary or even tertiary relationships to the air temperature, it’s a tougher connection to make,” Blumenfeld said.
It does, however, mean more precipitation in Minnesota.
As temperatures rise, oceans get warmer. Both of these factors mean more water evaporates off the oceans and ends up in the air as humidity. More humidity means more fuel for passing weather systems, i.e. more rain and snow, the effects of which experts say are being felt in Northwest Minnesota.
Randy Prachar has lived in northwestern Minnesota for 30 years. He works as the supervisor of the Roseau River Wildlife Management Area in Roseau County, Minnesota, along the Canadian border.
New infrastructure has had to be built to manage increased waterflow at the nearly 260,000-acre wildlife preserve, mostly wetlands.
Some of the wettest times are the spring, when increased rainfall has brought rising rivers that make it difficult for native diver ducks, like ring-necked ducks, which make their nests along waterways, to reproduce.
“After the water jumps up on the wetlands as a result of (a big rainfall event), we’ll see the adults gathering in the middle of the bay. What’s happened is the hens have lost their nest,” he said.
If it happens late enough in the season, it’s too late for duck pairs to try to nest again, which decreases populations.
But rising temperatures have created opportunity for other bird species, Prachar said: namely, wild turkeys.
“We used to have, on a map of Minnesota, a line running west to east across the state, and turkeys weren’t supposed to be able to survive north of there,” he said. “That’s been all blown apart. They’re up all the way to the Manitoba border.”
West of Roseau, the Karlstad Wildlife Management Area is situated on tallgrass aspen parkland — a sea of prairie and sedge punctuated by aspen and oak. Signs in the nearby town of Karlstad, in Kittson County, welcome visitors to the Moose Capital of the North. But that name fits the area less these days.
Minnesota is already the southern tip of the moose’s range. Now, the giant animals are under threat here from warming temperatures that make them more susceptible to parasites.
The moose is a key factor in maintaining the aspen parklands in the Karlstad Wildlife Management Area, said supervisor Ruth Ann Franke. Fewer of them makes more work for DNR staff.
“Here you have a large herbivore that likes to eat something like willow, so they definitely had an effect on keeping willows, say, at a knee-high or maybe even waist-high level. They didn’t get 12 feet tall,” she said.
In addition to fewer moose, a wetter landscape there means more brushy vegetation, which needs a higher water table to thrive.
The DNR manages the brush growth with machinery and prescribed burns, but when the ground is wet, machinery gets stuck and burns are less effective.
Consequences for farming
It’s not just animals that are feeling the effects of increased precipitation. It’s also crops.
While the growing season has increased by a couple days, increased precipitation in the spring and fall has added more uncertainty to farming, said Lindsay Pease, assistant professor and extension specialist in nutrient and water management at the University of Minnesota’s Northwest Research and Outreach Center.
Water is coming in bigger storms that are fewer and further between.
“It’s kind of a lost amount of water — the plant can’t pick it up, so even though the rain is falling, it’s not falling in a way that’s usable by the plants,” she said.
Farmers are increasingly installing sub-surface drainage, which helps fields drain more effectively.
“If we have wetter springs and warmer weather, I think we will likely see more of a need for subsurface systems,” she said.
Muddy fields can also mean less time for harvesting.
As it is, parts of Northwest Minnesota practically shut down during the sugar beet harvest as all available labor goes to getting the beets out of the fields.
“If that window gets smaller, it’d be more difficult to get the beets harvested. From a production standpoint, you could end up with lost yields because you don’t have access to the fields in the fall,” she said.