Reporter: Dan Kraker
Airdate: February 3 rd , 2015
I’m Minnesota Public Radio meteorologist, Paul Huttner. As we have documented in our special reports on climate change, Minnesota is facing a new climate reality. Temperatures are warmer, especially up north. And rain is coming in more intense bursts, with longer dry spells in between.
Those changes are expected to have severe consequences on some of the state's most treasured plants and animals, like moose and fish, spruce and birch trees. One strategy that's emerging to try to preserve some of those species is to protect places on the landscape where they can still survive in a much warmer world. Reporter Dan Kraker has our story.
Scientists call them "climate refugia." But think of them as "cold spots." They're unique places - microclimates - that could still support species that are adapted to colder conditions. Even in a
Minnesota that on average is likely to be several degrees warmer a few decades from now.
SFX: waves lapping on shore
Places like Ten Mile Lake, north of Brainerd.
"Ten Mile Lake is one of the gems of the state it's over 200 feet deep, very clear."
Pete Jacobson is a fisheries research supervisor with the Minnesota DNR.
"Just a beautiful lake, worth protecting."
The DNR has identified Ten Mile as one of 176 "refuge lakes" for a small but important fish called cisco, or tullibee. A lot of anglers haven't even heard of them. But they're a critical food source for valuable sport fish.
"Lakes where we have good cisco populations, produce very good growth rates on walleye, northern pike, lake trout, muskie, that’s where we see our biggest fish."
And THOSE species help support over 40 thousand fishing-related jobs in Minnesota, and nearly 3 billion dollars in spending every year.
But in the late 1970s cisco started dying. The DNR really took notice in 2006. It was an unusually hot summer. And dead cisco washed ashore by the thousands.
"If you’d go across a lake where there was a kill underway, you would see them on the surface, g asping for air. And you’ll see them dead and dying and floating on the surface."
Cisco need cold, well oxygenated water to survive. In Minnesota, that's down deep in clear lakes, below what's called the thermocline -- a kind of dividing line in the water, with warm water above, and cold water below.
In cold lakes with good water quality, there's enough oxygen for cisco all summer long.

"In a marginal lake, the deep waters will lose the oxygen from the bottom up, and by the end of the summer, the only available oxygen is just below the thermacline, in a very tight band."
And in really warm years, that band can get squeezed and squeezed until there’s just nowhere left for cisco to swim.
But even during the record fish kills in 2006, Jacobson noticed there were lakes where no cisco died. Deep, clear lakes like Ten Mile.
The key is water quality. And it's counterintuitive, but to get pure water, you need to focus on the land. The 176 refuge lakes are all largely surrounded by forests, which control erosion and soak up nutrients before they run off into lakes. Now the DNR is working to keep those watersheds forested through conservation easements, paying landowners to not develop their properties.
Jacobson estimates it will take $180 million to protect the refuge lakes.
"We have probably a 10 to 15 to 20 year window to do this. It’s a lot cheaper to protect than it is to restore an ecosystem.”
But by focusing on these select refuge lakes, Jacobson acknowledges they're giving up on some others.
“That’s one of the basic tenets of climate adaptation strategy, is sometimes you do have to give up on some resources. And s ome of those 650 lakes will not sustain cisco.”
Other lakes in the state will also likely not be able to support some of their current fish species.
Some walleye lakes in southern Minnesota, for example, could become bass lakes; some trout lakes in the future might be better suited for walleye. The DNR's Keith Wendt says it may be a waste of money to try to keep certain species in places where their preferred climate is just not going to be there.
"We can promise, I think, and fulfill good fishing, but we may not be able to promise the lake that you fished with your grandfather to catch walleye, you’re still going to catch walleye there. It may be a different species. And that’s the reality of a changing climate."
Some species' ranges have already changed. Take moose. They've largely disappeared from the northwest part of the state. In the northeast their population has been cut in half in less than a decade.
Moose may never again be as common here as they once were. They're already at the far southern end of their range. But maybe they can still hang on in some isolated places in
Minnesota.
That's the thinking behind ongoing research at Voyageurs National Park, where scientists are using GPS collars to track what kind of habitat moose seek out when it's really hot. The idea is to possibly protect or even create more of that habitat for moose in the future.
SFX: tromping through woods, twigs snapping
Similar research is being conducted in the Boundary Waters, where Dave Chaffin is also searching for warm weather refuges -- not for wildlife, but for trees.

"It’s going to be warmer, it’s going to be drier, a lot of the boreal species like black spruce, balsam fir, are going to exit the state, likely."
Late last summer the forest ecology grad student tromped through the forest off the Gunflint
Trail to collect 106 temperature sensors he'd placed around the BWCA in 2012.
SFX: “Now I’m just going to cut the sensor out.”
"We’re trying to find places, quote unquote cold spots, where a cold loving boreal tree species might be able to hide from the impending heat."
Climate models predict this part of Minnesota will be five to 12 degrees warmer by the end of the century. But Chaffin says those models use very "coarse grained" climate data based on sections of about 55 square miles.
But within those areas, there can be big temperature variations. The north side of a steep hillside, for example, is likely much cooler than high on an exposed ridge.
And while the data is still preliminary, University of Minnesota forest ecologist Lee Frelich, who's overseeing Chaffin's work, says they've found some pretty cold spots, especially on the eastern side of the Boundary Waters.
"Even with a major magnitude of warming, for example, there are some areas there that still may be as cold as Ely is now, and so some of the boreal species might be able to persist there."
Land managers in the future could then potentially set aside those areas as refuges for boreal trees.
This approach is the flip side to another strategy often referred to as "assisted migration," where forest managers would help species that are adapted to warmer, drier conditions -- like oaks, for example -- move north where they might be better suited for a changed climate.
It's controversial - many view it as an unnecessary manipulation of nature. So far it's not being done in Minnesota outside of experiments. But Frelich and others say it will likely be necessary to help forests regenerate.
SFX: some sound of waves lapping on shore
But DNR fisheries scientist Pete Jacobson says that doesn't mean we should just give up on cold climate adapted species, like boreal trees, the iconic moose, or the millions of cisco here in
Ten Mile Lake.
"It’s a question of what Minnesota is all about. We have this kind of an image of what I would almost call northness, that I think is something that we just kind of identify with in Minnesota and
I’d personally like to see that continue, even in a climate warmed Minnesota."
There might be just little pieces of it left, he knows. But he argues those little pieces of Up North are worth protecting.
Dan Kraker, Minneosta Public Radio News