Climate Change in Minnesota More heat, more big storms
Reporters: Dan Kraker and Elizabeth Dunbar
Air date: February 2nd, 2015
I’m Minnesota Public Radio meteorologist, Paul Huttner. It’s undeniable that Minnesota today is seeing the effects of a warming climate. That might seem contradictory just one year after the polar vortex froze us to the bone. But it’s a measured fact. Denying it ignores more than a century of data and extensive research. The statistics show Minnesota has warmed by about two degrees -- more in some places -- and is recording more destructive downpours. Dan Kraker and Elizabeth Dunbar dig deeper in this report.
Elizabeth Dunbar(ED):In 2012 nearly ten inches of rain poured through Duluth during a massive storm. Here’s how my colleague Dan Kraker described the scene.
“I'm standing behind the Whole Foods co-op on the east hillside in Duluth, about six blocks up from Lake Superior, where a huge retaining wall about twenty feet tall has been totally washed out. There's a gaping hole about twenty five feet wide, where a creek that normally runs underneath the parking lot here, has totally washed out the wall, it's a running, muddy torrent of chocolate, fuming water..."
ED:That must have been an amazing sight.
Dan Kraker(DK):It was. I’ll never forget that day -- some streets were so ripped up it looked like a war zone.
ED:And do you remember how just a few months before that? Minnesotans were basking in the warmest March on record.
SFX: sounds of St.Patrick’s Day parade
ED:I found this YouTube video. It shows people wearing shorts and tank tops in 80-degree weather at the St. Paul St. Patrick’s Day parade.
DK:That was surreal. And I know it was just one day, but if you look at temperatures across Minnesota, winters are warming significantly.
ED:And the Duluth storm was just one storm, but lately we’ve seen more downpours that flood homes and overwhelm roads and culverts.
DK:Species like moose and lake trout that love cold climates are disappearing. Maples are migrating north. Bugs that used to be killed off by cold winters are destroying tens of thousands of acres of forest. Lake Superior is one of the fastest warming lakes on the planet.
ED:This is Minnesota’s reality-- today. The climate has irrefutably changed. The statistical evidence is staring us in the face. It’s happening now, not off in some distant future.
DK:And what’s more, the changes we’ve already documented -- they’re expected to accelerate. But those changes can be tough to grasp.
"People tend to grab a hold of what’s happening now and offer that up as evidence of a trend either upward or downward in temperature or precipitation.”
DK:Greg Spoden is Minnesota’s state climatologist. He says when its hot people point their finger to climate change. When it’s not, he hears this:
'Hey, it’s very cold today, where is your climate change, Buddy?'"
ED:So those sounds of weather events you heard earlier? They’re examples of the types of extreme weather we’re more likely to see as the climate changes. But we’ve always had floods and heat waves. So we can’t pin any single event to climate change -- at least not without doing a complex analysis.
DK:But what we can do is analyze Minnesota’s long climate record to pick out trends in how the average weather has changed.
First, though, you need to understand the difference between weather and climate.
SFX: baseball announcer
Think baseball.
DK:Here’s how Spoden explains it.
“Weather are the individual at-bats and the individual games. The batting averages and the long-term statistics are the climate, and that’s where we come in: We’re Mother Nature’s scorekeepers.”
“You know this is day number nine of sub-freezing temps consecutively in November here and the record of course fifteen days back in 1880…”
ED:So when you hear MPR News meteorologist Paul Huttner describing the frigid stretch of days we had last November, you can’t cry foul on global warming. Spoden says that’d be like giving up on a player after just one game.
“If your best hitter goes 0-for-4, that’s not necessarily a trend and you’re not going to trade him or cut him. It’s a body of work over a course of a season or many seasons.”
ED:Minnesota has weather data going back even further than baseball statistics. That long record is how we know Minnesota’s climate has changed.
DK:The National Weather Service now has a network of 163 observers in Minnesota. Like clockwork, the volunteers send in daily temperature and precipitation data.
ED: That includes Milan, it’s a town of 350 in western Minnesota with deep Norwegian roots. Luther Opjorden’s farm is the local source of weather information here.
SFX: cats meow “They were born Memorial Day” SFX: chuckle
ED: Three kittens follow Opjorden on his daily visit to the temperature house. It’s a white box overlooking the farm.
ED: Two large, glass thermometers inside record the daily high and low temperatures.
“You spin the bottom one to bring that down to 48 so it’s ready for taking your temperature for the next day.”
SFX: spinning noise
ED: Opjorden has recorded temperatures as low as 33-below and as high as 100. Those extremes don't tell us much about the climate in Milan. But Opjorden's family has been at this for three generations, and their combined 121 years of daily weather observations do reveal a trend. On average, the temperature is about two degrees warmer than when Olaus Opjorden made his first observations here in 1893.
DK:And that’s just one of several dozen sites in Minnesota with weather observations going back 100 years or more.
DK: So when we say that climate change in Minnesota is real -- that it’s here, now, staring us in the face -- we can say that so confidently because of all of this data, these real weather observations collected by hundreds of volunteers throughout the state every day going back to the 1800s. That data proves two major ways the climate has changed in Minnesota. We’re dealing with heavier rains. And it’s getting warmer, especially in the winter.
ED: Let’s start with temperature. Average annual temperature in Minnesota has warmed by about two degrees. It ranges from a 1.3-degreesin south-central Minnesota to a 2.8-degrees in north-central Minnesota.
ED: Those might not sound like big changes, but a few degrees can have a major impact. How do we know? From another group of astute observers in Minnesota. They’re documenting changes they see in everything from plants and animals to lake ice.
SFX: digging at ice with jackknife
DK: Earlier this winter I headed out with John Latimer on a thin layer of ice on Crooked Lake near Grand Rapids. Latimer dug into the ice with a jackknife.
“I’m already two inches down, so it’s pretty thick.”
DK: Of course the DNR recommends four inches to stand on -- so Latimer, he tries to reassure me.
“Two inches will hold anybody.”
DK: And he should know. For the past three decades he’s carefully tracked the seasonal changes of the natural world around his home, including the date every year when Crooked Lake freezes over.
"Well this lake has been on average a half a day later a year for 30 years, so it's 15 days later now than it used to be.
DK: That's pretty significant! Latimer: Oh that is significant, yeah, a half a day a year is amazing."
ED: Latimer isn’t the only one seeing changes in lake ice. Ice cover on Lake Superior has declined by nearly 80 percent since the early 1970s. And the Minnesota Department of Natural Resources has noted a trend toward lake ice melting earlier in the spring.
DK: So when you combine all these real-world observations with almost two centuries of weather data, you not only prove Minnesota’s climate has changed, you understand it really means something.
DK:And those changes are even more pronounced in the winter -- average winter overnight lows have warmed by roughly 5 degrees since 1970, and we aren’t seeing as many record-breaking cold days.
ED: And the warming trend gets more pronounced as you travel north.
"Northern Minnesota is definitely bearing the brunt of that."
ED: University of Minnesota climate scientist Peter Snyder says one possible explanation is the snow and ice that cover northern climates in the winter act like a mirror. They reflect the sun’s rays outward -- it’s one reason why skiers and ice anglers often wear sunscreen.
ED:Without ice and snow, that heat from the sun gets absorbed.
“High latitudes, when it’s warming, you can get less snow, and the fact that you have less snow, uncovers the surface below it which might be less reflective, and that causes additional warming, which melts more snow and it goes around and around.”
DK: What’s happening in Minnesota fits with the global trends we’re seeing. Global temperatures are up about a degree and a half over the past century. Primarily because of the increased burning of fossil fuels.
DK:That’s increased the amount of heat-trapping carbon dioxide in the atmosphere by 40 percent since the 1800s. Overwhelming evidence shows we’re the primary cause of the rapid warming over the past 50 years. Natural factors like the sun and volcanoes...they could be part of it. But the vast majority of scientists say it’s just not possible they’re the only cause.
ED: Those warmer temperatures mean changes in where trees and plants can grow. Farmers are planting corn in northwestern Minnesota and northern North Dakota, where it used to be considered too risky to grow. The growing season in the Twin Cities is longer by several weeks since 1970.
ED: And some tree species, they seem to be migrating north.
SFX: walking through the fallen leaves
DK: The portage trail to Hegman Lake in the Boundary Waters back in October was carpeted with red and gold maple leaves. It’s a gorgeous patch of forest off the Echo Trail near Ely. Old growth red and white pines tower overhead. And underneath, sprouting everywhere, are the slender trunks of red maple trees…
“The leaves are down now, but the grey stems show up very well. And those are all red maple.”
DK: Chuck Wick, a retired Vermillion Community College instructor from Ely, has been observing the forest there for four decades.
“There’s always been red maple here. It’s hard to say quantitatively how much it’s increased. But anecdotally, it certainly seems like it’s on the rise.
DK:University of Minnesota forest ecologist Lee Frelich says Wick isn’t just seeing things. In his research elsewhere in the Boundary Waters, Frelich has counted many thousands of red maple seedlings per square mile. Meanwhile, he says, the pines are getting old.
“And when those pines go, when they die, which they inevitably will, they’re not going to be replaced by other pines, they’re going to be replaced by red maple, which is already there, waiting to take over.”
ED: Minnesota’s beloved North Woods -- the boreal forest of red and jack pine, spruce, birch and aspen -- those trees are at the southern edge of their range. And as the climate warms, their range is expected to shift northward.
ED: Taking their place will be maples, oaks, and probably less desirable plants that invade and spread really fast, like buckthorn.
DK: Scientists sometimes refer to “winners” and “losers” under climate change. That's because some species won’t tolerate a hotter Minnesota, while others will be more fit to survive. And some populations might even explode. Like bugs.
DK: Here’s DNR forest health specialist Jana Albers
“We like to think of them as the bellwethers of climate change. Because they’re the ones that are most sensitive to these changes in the environment.”
DK: Bugs like the deer tick, which transmits Lyme disease. The number of Minnesotans diagnosed with the disease has more than tripled since the mid-‘90s, in part because of an expanded tick range.
ED: So bugs and maples are winners, trees like red pines, losers.
DK: Yep. And it turns out Minnesota has a lot more of these winners and losers than other states. That’s because three major distinct ecosystems all come together here -- the prairie, boreal and deciduous forests. It’s at the edges of those where species will be most vulnerable to a changing climate.
ED: Species like Minnesota’s iconic moose. They’re also living at the southern edge of their range. But they’re disappearing. They've dropped from about 8 thousand to 4 thousand in the northeast corner of the state in less than ten years.
Researchers believe climate change is likely part of the reason. The Minnesota DNR is half-way through a landmark study trying to tease out what exactly is causing the collapse.
DK:Here’s where we are so far. We know Minnesota’s climate has already changed -- significantly -- because of these detailed climate records we have dating back to the 1800s. One of the main changes we’ve seen is that it’s gotten warmer, mainly in the winter. And that’s had profound impacts already on forests, lakes, human health, and plants and animals.
SFX: heavy rain
Now, the other dramatic change in Minnesota is in rainfall.
ED: Minnesota is wetter. But the even more profound change is how it rains. In this changed climate, when it rains, it’s more likely to pour.
ED: In fact there’s been a jump in the number of 2 ½ to 3-inch rain storms. That might not sound like much, but that’s a heavy rain. Until recently, you’d typically expect to see only one of those every five years wherever you live in Minnesota. Researcher Ken Kunkel at the National Climatic Data Center compiled the long-term data on these storms in Minnesota and the rest of the country. What he found was striking.
“The last decade actually has the largest number of these events since the network began in the late 19th century.”
DK: Kunkel says in the last 50 years, Minnesota and the rest of the Midwest have seen a 37 percent increase in the amount of precipitation falling as heavy rains.
DK: So the question is -- why?
“There’s more energy in the atmosphere, there’s more moisture in the atmosphere at a given time. We call it juice.”
DK: That’s the University of Minnesota’s Peter Snyder again.
ED: Hold on, Dan, that extra energy or heat in the atmosphere -- it’s connected to rainfall?
DK: Yep.
ED:I think this calls for another baseball analogy.
DK: Go for it.
SFX: “And the 2-1 pitch Breaking ball hit deep to left field!”
ED: In 1998, Mark McGwire and Sammy Sosa were chasing the single season home run record.
SFX: crack“Number 50 for Mark McGwire!”
DK: I remember -- it was one of the most exciting seasons ever.
ED: Of course McGwire became one of several high-profile players who later admitted using performance enhancing drugs. And though no individual home run can be credited to drug use –I mean, you’d expect McGwire to hit some number of homeruns -- the stats show players hit more homeruns during the juicing era.
ED: So, just as steroids supercharged baseball statistics, human-influenced global warming has supercharged our rainy days. Peter Snyder says that’s because a warmer atmosphere holds more water vapor.
“We have more energy and more moisture to work with so that if we have all the ingredients we need to produce a thunderstorm, that thunderstorm ought to produce more rainfall.”
DK: That might be what happened in 2014 in southern Minnesota. University of Minnesota Extension educator Jeff Vetsch oversees a weather station in Waseca that’s collected data for 100 years, and June 2014 was especially remarkable.
“Our wettest month ever in 100 years of records. We had three days with 2 inches of rain in a four-day period. That had never been reported by an observer in our state ever.”
ED: When several two or three-inch storms happen in the same week or month, they can cause some serious damage.
ED: Across southern Minnesota, the wet weather wiped out crops and overwhelmed wastewater systems. Sewage had to be pumped into lakes. The rain flooded basements and bike trails and caused a mudslide on a Mississippi River bluff near the University of Minnesota Medical Center.
DK: Huge storms that dump at least 6 or 7 inches of rain in a day -- and cover a huge geographic area -- are also becoming more frequent.
DK:State Climatologist Greg Spoden
"We've looked at historical records, diaries, newspaper accounts, and we've found a dozen or so of these mega rain events."
DK: That's since Minnesota became a state, in 1858.
"About five of them have occurred in just this century."
DK: Which means Minnesota saw seven mega rain events in its first roughly 140 years. And five in just the last 14.
ED:And of those five, three were unprecedented. They pummeled southern Minnesota in 2004, 2007 and again in 2010. During that 2007 storm 15 inches fell on the town of Hokah -- the largest 24-hour rainfall total ever recorded in the state.