Assign to Google Classroom
Mauri Pelto digs his boots into the steep icy slope on Mount Baker. It is in Washington State. He watches as streams of water cascade off the thick mass of bare, bluish ice. Every 20 yards, the water carves vertical channels in the face of the glacier as it rushes downstream.
What little snow from last winter is already gone. Ice is melting off the glacier at a rate of nearly three inches a day this summer, he said.
"At the rate it is losing mass, it will not make it 50 years," said Pelto. He is a glaciologist who returned in August for the 32nd year to study glaciers in the North Cascades range. "This is a dying glacier," he said.
Glaciers on Mount Baker and other mountains in the North Cascades are thinning and retreating. Seven have disappeared over the past three decades. The glaciers in the range have lost about one-fifth of their volume.
The shrinking glaciers here mirror what is happening around the U.S. and worldwide. As the planet warms, glaciers are losing volume. Some are disappearing faster than others.
Two of the largest glaciers in Yosemite National Park in California have retreated over the past century. They have lost about two-thirds of their surface areas. In Alaska, a study of 116 glaciers estimated they have lost about 75 billion metric tons of ice every year. That is from 1994 to 2013. In Montana, scientists are seeing the impacts in higher stream temperature. And also in changes to high-elevation ecosystems. In 1850, there were 150 glaciers at Glacier National Park. Now there are 25.
"These glaciers are, from a geological standpoint, rapidly disappearing from the landscape," said Dan Fagre. He is a research ecologist with U.S. Geological Survey. He is stationed in Glacier National Park. "They are so small and vulnerable that they could be gone in a matter of decades."
Glaciers are thick masses of collected snow. They compress into ice and move. Glaciers are important guides for climate change. That is because they are driven by precipitation and temperature.
Mount Baker is a volcanic peak about 125 miles northwest of Seattle. The glaciers on Mount Baker provide a critical water source for farming, cities and tribes during the late summer. The icy glacial melt keeps streams cool for fish and refills rivers. The melt comes during a time of year when they typically run low.
The Nooksack Indian tribe has relied for hundreds of years on salmon runs in the glacier-fed Nooksack River. That way of life is at risk. Without that glacial runoff, rivers will dry up more quickly and warm up faster. It will make it harder for salmon to spawn or move to the ocean.
"Climate change will impact the ability of tribal members to harvest fish in the future," said Oliver Grah. He is water resources manager for the tribe. The tribe has teamed up with Pelto. They want to know how glacier runoff will affect the river's hydrology. And also the affect it will have on fish habitats and restoration planning.
On a recent day, Grah and colleague Jezra Beaulieu hiked 5 miles into the Sholes Glacier. They wanted to study how climate change will influence the timing and degree of stream flow in the river. It is their fifth field trip to the glacier this summer. Each time, they are amazed at how quickly the snow and ice are melting.
Grah strings a measuring tape across the stream. Then he wades in shin-deep in the fast-moving, brownish water. He measures the depth of the water streaming from the toe of the glacier. He calls out numbers that Beaulieu records in a yellow notebook. They are trying to figure out how much flow and sediment is coming from the glacier.
"This is a frozen reservoir that yields water all summer long," said Pelto. He is a professor of environmental sciences at Nichols College. It is located in Dudley, Massachusetts. "So you take this away and what are you going to replace it with?"
The tribe also is working with Western Washington University. The college is using data collected in the field. That information is used to model what the stream flow will be like in the future.
"The late summer flows controlled by melting glaciers are predicted to decrease as the glaciers get smaller and smaller," said Robert Mitchell. He is a geology professor at Western Washington University.
This year, a record low snowpack in Washington state and warmer temperatures have made it one of the worst Pelto has seen in over three decades.
"They are losing volume at a faster rate than ever before," Pelto said. "If you cannot sustain a glacier at a place like this in the Lower 48 states, there is no hope."
CRITICAL THINKING QUESTION
Why does Mauri Pelto describe this as a "dying glacier?"
Write your answers in the comments section below