NORTH CASCADES NATIONAL PARK, Wash. -- Jon Riedel’s white hair and light blue eyes match the icy tint of the landscape he’s studied for more than 30 years.

He moved to Washington soon after finishing his PhD at the University of Wisconsin because he says the glaciers of the Northwest are still writing the landscape, still carving out curves and valleys.

Outside of Alaska, there is no better place in the U.S. to study glaciers than Washington. The Cascade Range has the perfect elevation and weather patterns to ensure that wet, heavy snow piles on thick and sticks around. Skiers here call it “Cascade concrete.”

“That’s the key to forming a glacier,” Riedel says. “High, cool mountains with heavy, wet snowfall is perfect for forming ice because the snow in many parts of these mountains lasts through the summer and then gets buried by snow the following winter.”

NPR's Michele Norris and KUOW/EarthFix reporter Ashley Ahearn will lead a conversation centered around storytelling about our greatest ally and one of our biggest threats: water.

But not powerful enough to withstand humans and our contributions to global climate change.

“Since 1900 we’ve lost about 50 percent of our glacier area in the North Cascades National Park. And that’s pretty typical for mountain ranges around the world,” Riedel said during a recent hike up to Easton Glacier on Mount Baker.

Glaciers set this region apart. Their meltwater runs through faucets and garden hoses. Their runoff allows fish to navigate streams when rainfall is scarce. Their high-elevation trickle eventually gathers in rivers with currents powerful enough to generate hydroelectricity for millions of residents.

And they make the Northwest uniquely vulnerable to the effects of climate change.

Scientists like Reidel don’t dispute that there have been natural patterns of warmer and cooler periods throughout the planet’s history. Glaciers have advanced and retreated hundreds of times over the Cascade mountains.

But Riedel says in the past few decades the Northwest’s glaciers have melted faster than ever before, the recent pattern of cooler, wetter weather notwithstanding. The remains of ancient forests, buried thousands of years ago when the glaciers advanced, are reemerging as the glaciers relinquish vast swathes of mountainside real estate. Riedel points out their ancient trunks, protruding from the rocky soil, as he walks along the path of the Easton glacier’s retreat.

“The glaciers now seem to have melted back up to positions they haven’t been in for 4,000 years or more," Riedel says, explaining that natural influences alone can't possibly account for glacial retreat on such a scale.

“If you were here in 1907 you’d be looking right at the terminus of the glacier. Now it’s around the corner. You can’t see it,” Riedel says as he looks up the rocky slope.

Since the beginning of the 20th century, this glacier has retreated more than half a mile from where Riedel’s standing.

“As a scientist, every time I come back here, this place has changed,” he says.

Watch A video of the melting Easton Glacier

Riedel says the glaciers may be here through the end of the century, or perhaps longer. He’s hesitant to make an estimate, as are many scientists, because the rate of climate change could accelerate in the future. But he stresses that in the face of a changing climate, places like this have the most to lose.

“The biggest changes you’re seeing as a result of a warming climate are occurring at the poles and in the mountains,” Riedel explains.

The Easton glacier is one of 376 glaciers that feed the Skagit River. The meltwater comes at a critical point in the late summer, when this region gets less rain than Tuscon, Arizona. Billions of gallons of glacial runoff supplements rivers like the Skagit, providing a critical source for hydropower generation, fish survival and drinking water for thousands of people in communities downstream.

The Skagit might be the Northwest’s most studied and most glaciated watershed. But it’s hardly the only river in the region to begin with the trickle of glacial melt. Communities up and down Puget Sound draw water from rivers like the Nooksack and the Nisqually, which are fed by glacial runoff.

Seattle is one of the fastest-growing cities in the country, and 90 percent of the city’s power comes from dams. Those dams do not rely exclusively on glacial runoff to function, but glaciers play a critical role in how water is metered out throughout the year. During the drier summer months, glacial runoff makes up a larger portion of the water coursing through rivers - and dams - across the region.

“That water is coming at a time when we don’t have a lot of other runoff,” says Crystal Raymond, head of the climate change adaptation and research program for Seattle City Light, which provides half of Seattle’s hydropower. “So it’s really critical in late summer for protection of fish, for maintaining reservoir levels for recreation and generating hydropower.”

Watch A video about Ross Dam on the Skagit River

Climate scientists say just a slight uptick in temperature could mean giant changes for the region’s hydropower generation. It comes down to that fine line on the thermometer that marks the difference between a great day of skiing or a soggy day on the slopes.

For Raymond and other hydropower managers in the Northwest, that fine line is causing a bit more heartburn than a wasted lift ticket. When rising temperatures make more precipitation fall as rain instead of snow, dams have to release or “spill” more water, instead of storing it, to prevent flooding.

“That is essentially a loss of water that could be used for power generation,” Raymond explains.

Compared to snow, rain races off the landscape and rushes through hydropower facilities. You might think of snowpack as a liquid savings account, metering out water later in the year (or covering you when you’re waiting for your next paycheck).

Glaciers then, represent your retirement savings, storing water away for use in the more distant future, when your other sources of income dry up.

By the time millennials are retiring, summer hydropower production in the Northwest is expected to be down by roughly 15 percent.

Managing hydropower for climate change, like planning for retirement, just takes a bit more forethought, Raymond says. Expanding dam reservoir capacity and changing how much water is released at different times of year will help. So will improving energy efficiency for homes and businesses.

“It isn’t hopeless,” Raymond says. “There’s a lot of uncertainty, but we know enough now to start getting prepared.”

“She’ll sit on that redd and defend it until she loses energy and dies,” Erin Lowery explains, peering over the side of the boat and into the clear waters of the Skagit River. He’s watching a spawning chinook salmon guarding her nest, or “redd,” below. The female’s tail is ragged and white where she’s used it to shovel away the gravelly riverbed, creating a series of hollows where she lays her eggs -- a triumphant last hurrah.

Lowery spends a lot of time monitoring the spawning of steelhead, bull trout, and salmon in this river. He’s a fisheries biologist for Seattle City Light, which means it’s his job to make sure the utility releases enough water to allow the fish that are spawning downriver from the dams to successfully reproduce. Too much water spilled and eggs can be washed away. Too little and they’ll be left high and dry.

“We mark them, we measure them and then we attempt to provide protection for them if we can,” he says.

As a boy growing up in Seattle’s fishing community of Ballard, Lowery would never have guessed he’d end up working for a power company that’s responsible for dams.

“Hydropower was one of the problems with salmon recovery and part of the decline,” Lowery recalls. “As I started to learn more though, I realized that there’s ways to make things work.”

The Skagit River, unlike others that feed into Puget Sound, is home to all five types of salmon and steelhead, as well as threatened bull trout. Lowery says that’s in part due to good management by the utility. But we also have glaciers to thank.

“During the warm months when glaciers melt, they will provide flows for certain streams for fish,” but perhaps more importantly, he explains, they inject cold water into warming summer streams, “which is key to coldwater fish like salmon and trout.”

The glaciers aren’t going to disappear tomorrow. And Lowery says Seattle City Light isn’t imminently faced with the choice of either providing power to hundreds of thousands of people or keeping fish alive.

In the more immediate future, the utility will probably need to draw down the North Cascades’ Ross Lake reservoir during drier parts of the year, affecting people's recreation before any fish suffer below the dams. During heavier rainfall events it may need to spill more water over the dams. But eventually, Lowery says, tougher decisions will have to be made.

“As we move forward it’s going to be a hard look at how we manage flows in the river with a changing climate, and how we can balance the needs of fisheries and people that live in the Pacific Northwest,” he says, looking off down the river. “People are moving to the Puget Sound constantly, and they’re all going to need electricity.”

Video produced by Ryan Hasert

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Jon Riedel, standing just below the Easton Glacier of Mount Baker. He has been monitoring glaciers for the National Park Service for more than 30 years. He's documented the rate at which glaciers in the North Cascades have been shrinking in recent years.