Leif Olmanson has spent most of his career tracking Minnesota’s lakes from space, poring over decades of satellite images and crunching data on water clarity.

Now the University of Minnesota researcher is puzzling over a new question: What is driving the declining water clarity in Minnesota’s northern lakes, some of the jewels of the state?

“My big concern is that the areas that are more pristine are where things are changing quickly,” Olmanson said. “Why would these lakes be changing in northern Minnesota where there’s not a lot of land use changes going on?”

Olmanson quickly mapped the state’s late summer temperatures — the dog days when algae blooms — and saw they have risen fastest in Minnesota’s north-central regions where lakes have been warming the most. This is the home of deep, cold lakes. Bit by bit, the change in a few degrees could alter the state’s prized cabin country and angler havens.

“That’s some of the best walleye fishing in the country,” said retired DNR fisheries research biologist Peter Jacobson. “It’s a part of the state we’re very concerned about.”

Other scientists at the U, the Minnesota Pollution Control Agency and the Department of Natural Resources (DNR) are monitoring the trend, too.

Casey Schoenebeck, a research scientist who runs the DNR’s sentinel lakes program, said Olmanson’s heat map is supported by what his team has found in the water. Lake water temperatures are rising statewide, but particularly in the state’s transition zone from the plains to forest and in the northern forest area.

“It’s all changing,” Schoenebeck said, “but the changes are happening the fastest in those two central eco-regions.”

Warmer water encourages the algae growth, including the toxin-producing cyanobacteria commonly called blue-green algae. It can clog fish gills, and when it dies and sinks to the bottom of a lake it consumes oxygen, starving fish and other aquatic life.

The murkiness can actually amplify the warming temperatures, said Gretchen Hansen, another U scientist studying the decline in water clarity. Murky surfaces absorb more of the sun’s radiation, warming surface waters even faster.

The most ominous sign of the impact is the plunge in cisco populations across the Midwest as lakes warm. Also called tullibee, the small silvery fish are a main source of food for prized game fish such as walleye. They thrive in bands of deep cold water, and are highly sensitive to temperature changes. The DNR has been working to try find “refuge” lakes for them.

There are multiple factors that can make Minnesota lakes murkier, that Olmanson, Hansen and others are trying to untangle, such as changes in precipitation and, perhaps more important, in land use.

Minnesota is losing forests to farmland as row crops spread north, for example, as timber is harvested and as communities grow with new homes, businesses and roads. Then there are cabin owners tinkering with shorelines.

Plus, more intense rainstorms wash more nutrients, sediments and solids, such as leaves, into lakes with tannins that turn water brown.

As Peterson, the retired DNR biologist, sees it, the solution to protecting water quality in the state’s deep clear lakes is to protect the intact forests around them. If 75% of a lake’s watershed is forested, you can protect it, he said.

“It’s critical that it does not get converted to agriculture or homes, and shopping centers and roads,” Jacobson said.

That’s what the Northern Waters Land Trust has been working on. Based in Walker, Minn., the nonprofit conserves private land on strategic tullibee refuge lakes in Cass, Crow Wing, Hubbard and Aitkin counties. It uses grants from the state’s sales-tax funded Outdoor Heritage Fund to arrange conservation easements for landowners and has protected nearly 2,500 acres that way since 2014. The trust also buys land outright.

Olmanson said the approach makes perfect sense: “It’s cheaper to protect the lake before it gets impacted than to try to restore it.”

To explore the effects of land-use changes on water clarity, Olmanson is analyzing new satellite-derived data that show changes in land cover. His goal is to build an automated data set to show which factors are most important in driving declining water clarity in different lakes.

“Different things are happening in different parts of the state,” he said. In the near term, he’s racing to finish a major update of the U’s interactive LakeBrowser tool in time for this year’s fishing opener May 15. It’s popular with anglers and real estate agents.

The tool, which Olmanson helped create, displays information about the clarity of all Minnesota lakes down to 10 acres in size. It shows a lake’s current and historic clarity measures and comparisons to other lakes in the watershed, for example, how much algae it has and the nature of the land around it, such as forest or fields. It complements the DNR’s LakeFinder tool.

The map Olmanson generated of late-summer temperature changes in Minnesota’s center north reflect a broader pattern, climatologists say.

Northern Minnesota is warming faster than southern Minnesota, with north-central and northeast Minnesota warming a little more than west-central Minnesota, said Kenneth Blumenfeld, senior climatologist in the state Climatology Office.

If you zoomed out from Olmanson’s map, Blumenfeld said, it would show that high readings in north-central Minnesota are part of a larger continuous belt extending north into Canada. In general, the farther north you go around the world, the faster warming is occurring. There are variations on our continent, he said, where the interior is warming faster than near the coasts.

“Northern Minnesota has some of the fastest warming rates in the contiguous U.S., including during the late summer,” he said. “The variations we see to the east and west are based on topography, elevation, land cover, proximity to water, and other factors climate scientists do not fully understand.”

Excess energy from windfarms could be stored as hydrogen

Last year was a record breaker for the UK’s wind power industry.

Wind generation reached its highest ever level, at 17.2GW on 18 December, while wind power achieved its biggest share of UK energy production, at 60% on 26 August.

Yet occasionally the huge offshore wind farms pump out far more electricity than the country needs – such as during the first Covid-19 lockdown last spring when demand for electricity sagged.

But what if you could use that excess power for something else?

“What we’re aiming to do is generate hydrogen directly from offshore wind,” says Stephen Matthews, Hydrogen Lead at sustainability consultancy ERM.

His firm’s project, Dolphyn, aims to fit floating wind turbines with desalination equipment to remove salt from seawater, and electrolyzers to split the resulting freshwater into oxygen and the sought-after hydrogen.

The idea of using excess wind energy to make hydrogen has sparked great interest, not least because governments are looking to move towards greener energy systems within the next 30 years, under the terms of the Paris climate agreement.

Hydrogen is predicted to be an important component in these systems and may be used in vehicles or in power plants. But for that to happen, production of the gas, which produces zero greenhouse gas emissions when burned, will need to dramatically increase in the coming decades.

Mr. Matthews says his firm’s project is just getting going, with a prototype system using a floating wind turbine of roughly 10 megawatt capacity planned, but not yet built.

It’s possible that the system could be based in Scotland and the aim is to start producing hydrogen around 2024 or 2025.

But there are many other ventures in this area besides Dolphyn.

Wind turbine maker Siemens Gamesa and energy firm Siemens Energy are ploughing 120m euros ($145m; £105m) into the development of an offshore turbine with a built-in electrolyzer.

German energy company Tractebel is exploring the possibility of building a large-scale, offshore hydrogen production plant powered by nearby wind turbines; and UK-headquartered Neptune Energy is seeking to convert an oil platform into a hydrogen production station, which will pump hydrogen ashore to the Netherlands via pipes that are currently transporting natural gas.

There are plans to convert this old North Sea oil platform into a hydrogen production plant

All of the excitement around hybrid wind energy and hydrogen generation systems is partly down to climate commitments but economics are also involved.

Large-scale hydrogen electrolyzers are becoming more available while the costs of installing wind turbines has fallen “dramatically”, says James Carton, assistant professor in sustainable energy at Dublin City University.

He and others think the time is right to kick-start large-scale hydrogen electrolysis at sea, though the idea has been around for many years.

Electrolyser stacks break seawater down into hydrogen and oxygen

Oyster is yet another project in this area, and involves a consortium of companies including Danish energy firm Ørsted and British electrolyzer specialists ITM Power, among others.

In the first instance, a wind turbine will power an onshore electrolyzer that will churn out hydrogen. The device will be exposed to sea spray to simulate, to a degree, the harsh environment facing offshore equipment. ITM intends to design a system compact enough to fit into a single wind turbine.

The firm’s chief executive, Graham Cooley, points out that it is much easier to store molecules such as hydrogen than electrons in batteries.

“All the renewable energy companies… they’ve realized they’ve got a new product,” he adds. “Now they can supply renewable molecules to the gas grid and industry.”

The Oyster consortium hopes to have shown off a demonstrator of its system within 18 months.

Among the many potential uses for hydrogen is as a fuel for gas-burning boilers in homes. Converting the domestic gas grid to provide hydrogen, and fitting homes with boilers capable of burning it, would be a huge task.

However, it would mean that excess wind energy could in principle be used to supply this giant system, meaning very little of that energy would go to waste, says Mr. Carton, referring to the gas main pipes scattered around the UK and Ireland: “We have a big tank, it’s just a really long tank in the ground.”

For some, this is all very exciting. But there are hurdles yet to overcome. A spokesman for the wind energy industry body WindEurope says that while renewable hydrogen produced via wind-powered electrolysis is “future-proof”, a decade or so of technological development is required before these systems will have a larger impact.

Jon Gluyas, Ørsted/Ikon chair in geoenergy, carbon capture and storage at Durham University, adds that the real question is whether it is cost-effective to set up such equipment at scale. Proponents, unsurprisingly, argue it is – but with energy systems the proof is only ever in the pudding. Ultimately, Prof Gluyas says a mix of different technologies and approaches will be needed for countries like the UK to be carbon neutral.

For Mr. Carton, the vision remains tantalizing. Schemes that solve the problem of wind’s variability by using excess power to good use could be transformative, he argues: “It’ll change the way we look at renewables.”

DETROIT – Care for a plate of slimehead? How about some orange roughy?

It’s the same fish, but one sounds much more palatable than the other. The U.S. National Marine Fisheries Service gave the slimehead a rebranding in the late 1970s in an effort to make the underused fish more marketable.

Now, Illinois officials and their partners want to give the invasive Asian carp threatening the Great Lakes a similar makeover. The goal: To grow the fish’s image as a healthy, delicious, organic, sustainable food source — which will, in turn, get more fishermen removing more tons of the fish from Illinois rivers just outside of Lake Michigan.

Markets such as pet food, bait and fertilizer have expanded the use of invasive Asian carp in recent years. But “it’s been hard to get the human consumption part of this because of the four-letter word: carp,” said Kevin Irons, assistant chief of fisheries for the Illinois Department of Natural Resources.

A full-on media blitz is coming later this year to change that. The proposed new name for the fish is being kept tightly under wraps for a big rollout in June, prior to the Boston Seafood Show in mid-July. But other aspects of the “The Perfect Catch” campaign will point out that the invasive Asian carp species — silver, bighead, grass and black carp — are flaky, tasty, organic, sustainable, low in mercury and rich in protein and omega-3 fatty acids.

“To us in America, we think of carp as a bottom-feeding, muddy-tasting fish, which it is sometimes,” said Dirk Fucik, owner of Dirk’s Fish and Gourmet Shop in Chicago, who has had success with occasional serving of Asian carp to customers and is participating in the rebranding effort.

“But Asian carp is a plankton-feeder. It’s a different type of flesh — much cleaner, sweeter-tasting meat.”

Fucik called the upcoming national marketing campaign “the biggest push that we’ve seen so far with these fish.”

Asian carp were introduced in the southern U.S. in the 1960s and ’70s to control algae blooms in aquaculture facilities, farm ponds and sewage lagoons. Floods and human mismanagement helped the carp escape into the Mississippi River system, where their spread exploded.

A 2019 study looking at 20 years of fish population data on the upper Mississippi River confirmed bighead, silver, grass and black carp out-compete sport fish, causing population declines for prized species such as yellow perch, bluegill, and black and white crappie.

Should Asian carp make it into the Great Lakes, many scientists believe they would cause a huge disruption to the aquatic food chain and damage, perhaps irreparably, a $7 billion annual Great Lakes fishery.

Plans are in the works for a $778 million Asian carp barrier at the Brandon Road Lock and Dam on the Des Plaines River about 27 miles southwest of Chicago in Joliet, Illinois. The barrier will include electricity, unappealing sounds for fish and gates of bubbles as deterrents.

But old-fashioned fishing of pools of carp in the river systems between the Mississippi and Lake Michigan is also proving effective in holding back the potential Great Lakes invaders.

Shawn Price, a commercial fisherman based in Fulton, Illinois, has fished the rivers for Asian carp on contract with the Illinois DNR since 2010. Then, they caught boatloads of carp, almost all 20 to 50 pounds, he said, with some up to 70 pounds or more. Now, the fish are typically 3 to 12 pounds, or even smaller, he said.

“We almost never catch a fish over 30 pounds anymore,” he said. “That mass that was there when we started, when they said they have to do something to save the lake, we have drastically cut it to shreds.”

Back when the program started, bighead carp made up about three-quarters of the catch. Now, they are less than 10%. The difference? Fishermen catch the bighead carp more easily, so they’ve caught them in far greater numbers over the years. “The bigheads don’t jump, the silvers do,” Price said.

It’s silver carp that provide the iconic images of fish jumping out of the water en masse, potentially endangering boaters. Fishermen can have silver carp trapped in six rows of netting “and they will jump over all six of them,” he said.

‘A huge opportunity for this market to expand’

State-contracted fishermen like Price drop their loads off at the dock, with state officials setting up markets for the carp.

“A lot of the fish are used for organic fertilizer, pet treats,” he said. “They sell a fair amount for … lobster bait, crawfish bait.”

Roy Sorce’s family ran a food service distributorship in Illinois for 49 years. Last year, he converted the business to Sorce Freshwater, seeing a future in Asian carp.

“We take the fish from the fishermen and we find markets to sell them,” he said — bait and fertilizer companies, as well as pet food and for human consumption.

What started as 30,000 to 40,000 pounds of fish a week is now up to 80,000 pounds, with plenty of room to grow, he said. He hopes to add on-site processing of the fish in coming months.

“There’s a huge opportunity for this market to expand,” Sorce said. “We’ve already made inroads … it all has to do with education and marketing. Because of COVID, everyone is so tied up with other issues and priorities. They don’t want to deal with something new, or try something new, yet.”

In Kentucky, Asian carp have moved from the Mississippi and Ohio rivers into tributaries and in two of the state’s biggest reservoirs, Kentucky and Barkley lakes. Peoria, Illinois-based Colgan Carp Solutions has worked with fishermen there to take Asian carp for use as lobster bait in New England.

“The fishermen liked it — they said it fishes well. It’s an oily fish,” founder Brian Colgan said.

COVID-19’s impacts on tourism and restaurants have hit the lobster market hard as well, so demand dried up over 2020, he said.

“The good news is the fishermen started calling again in September and October,” he said.

In Canada, Montreal-based Wilder Harrier last year introduced an Asian carp-based dog food.

“We want to tackle the unsustainability of our food system at large … the heavy use of animal protein in a growing human population of 10 billion people that we just cannot sustain,” company co-founder and CEO Phillippe Poirer said. “We decided to start with our pets.”

Among the company’s products are pet treats made from protein from crickets and a species of fly. Learning of the Asian carp problem just outside the Great Lakes, it seemed a fit, Poirer said.

“Trying to reduce the environmental impact of our food system includes protein sources from species that are damaging our ecosystem, such as invasive species,” he said. “Asian carp has a lot of small bones and really is not ideal as a fillet fish for human consumption. But once ground up, it’s perfect for cats and dogs. It has a great nutritional profile, and it’s very appetizing for them.”

Ah, them bones. Asian carp have many tiny pin bones throughout their fillets. They’re actually so small as to be edible, but they are a hurdle for an American market, Fucik said.

“American people do not like bones,” he said. “Chinese people will eat a fish right off its bones, but in America, people want a 4-ounce salmon fillet, skinless, boneless, that grows on a tree.”

Some higher-order filleting and meat-grinding, however, can overcome the pin bone issue, Fucik said.

The upcoming Asian carp — or whatever the fish will soon be called — marketing push will seek to connect with grocery stores, restaurants, and institutional places such as universities and food pantries. “Anybody who needs to eat proteins,” Irons said. The message: “If you try it, it’s going to be delicious.”

And it’s all for a vital environmental cause. Sorce noted that the Brandon Road Lock and Dam Asian carp barrier proposed for Peoria is still about seven years or more away.

“We are a last line of defense,” he said. “If we can harvest these fish out of the Peoria pool, we can minimize the pressure going north.”