At a Glance

The Northern Cascades glaciers have shrunk by 30%.They are shrinking due to global warming, a lead scientist said.The glaciers help provide drinking water to the Seattle area.

Professor Mauri Pelto has surveyed glaciers in Washington's Northern Cascade Mountains every summer for more than three decades. This year, he and his research team were stunned by what they saw.

"The bottom line for 2019 is the ," Pelto wrote in a recent blog post at glacierhub.org.

Pelto is the U.S. representative to the World Glacier Monitoring Service and a professor of environmental science at Nichols College in Maine. He's also director of the Northern Cascades Glacier Climate Project, which conducts the annual surveys. In a phone interview Friday, Pelto told weather.com he didn't expect to see such a rapid rate of melting when he started the project 36 years ago specifically to track the effects of global warming on the glaciers.

"Currently, about three-quarters of the glaciers I look at won’t survive, and that’s with the current climate," Pelto said. "If the climate changes, that number will rise."

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Annual melting of glaciers is critical to water supplies and other resources. The , for example, help provide drinking water to Seattle and irrigation to farmers in the region. But when glaciers completely disappear, that water supply dries up.

"It’s pretty evident what’s happening in terms of how little snow cover they have left on them and how much meltwater there is running off in any given day," Pelto said.

Smaller glaciers disappearing isn't as concerning, according to Pelto, but the fact that "they have done so relatively rapidly is an indicator. I'm worried about the rest of the glaciers that are on the path to disappearing."

Glaciers around the world are shrinking as climate change brings a warmer atmosphere and disruptions in weather patterns. Pelto compared it to a recession, where one economy is affected, and then another, and then another.

"The climate change is big enough that they're all getting hit over the head," he said. "It's kind of a globally unified response to the warming climate."