Alaska’s Glaciers Are Retreating
Although the mechanisms vary, together the glaciers are losing 75 billion tons of ice annually
The USGS research has focused on two glaciers that represent two very different Alaska climates — the Gulkana Glacier in the eastern Alaska Range south of Fairbanks and the Wolverine Glacier in the Kenai Mountains on the southern coast of Alaska.
At both locations, the long-term records show that summer warming has resulted in sustained mass loss, noted Shad O’Neel, head of the glacier research program at the USGS Alaska Science Center.
“How the climate has been changing over the past few decades of anthropogenic influence really has manifest itself quite well” in these studies, O’Neel said. “It provides tangible evidence for how climate change is affecting the landscapes.”
Since the 1990s, the retreat of glaciers in Alaska has made a disproportionally large contribution to global sea-level rise. The USGS reports that the state’s glaciers are losing 75 billion tons of ice annually, equal to the amount of water needed to fill Yankee Stadium 150,000 times each year.
During that time, the Gulkana Glacier has steadily diminished due to significantly warmer summers in interior Alaska and a relatively unchanged level of snowfall. Gulkana drains west into the Yukon River.
Meanwhile, the Wolverine Glacier, which is also shrinking, has experienced slightly cooler summers and more variability in winter temperatures. That glacier is a coastal system that flows into the Gulf of Alaska.
USGS estimates that Alaska’s glaciers and ice fields are responsible for nearly 50 percent of the water that flows into the Gulf of Alaska. The meltwater has a unique “glacial fingerprint” that is evident in the timing, volume and temperature of the water, as well as the nutrients it carries. It also influences the rich diversity of species in the marine ecosystem that are important to tourism and fishing industries.
To study those impacts, the glaciologists are teaming up with ecologists, oceanographers, biologists and botanists to assess how socio-economically important species like salmon are likely to fare in the warmer Alaska of the future.
“We’re trying to quantify the water flow, the water chemistry and then the vegetation that’s in the basin, the species that are there, all the way from the glacier terminus down to the ocean,” O’Neel explained.
“We had a team of biological oceanographers that went into Kings Bay, which is where Wolverine drains into,” he said. “They were able to see a pretty pronounced gradient of both physical and biological composition of what’s living in the bay. So we’re getting some core baseline biological data to go with the physical drivers that go back 50 years.”
In the years since the USGS launched its landmark Alaska glacier research, the scientists have also begun combining their field studies data with new information gathered with modern geophysical and remote sensing methods.
And they’re now modeling how glaciers will respond to future climate scenarios, particularly how coastal glaciers like Wolverine impact the ecosystem along the Gulf of Alaska.
According to the USGS, climate change could cause summer temperatures to warm by 3.6 to 7.2 degrees Fahrenheit, and snow accumulation to markedly decrease. Those changes could contribute to the loss of thousands of glaciers in Alaska and northwest Canada by the end of the century.
Today, the federal benchmark glacier program extends beyond Alaska and includes research at the South Cascade Glacier in Washington state and the Sperry Glacier in Montana. Experts say those glaciers are influenced by different climates, allowing scientists to compare how glaciers respond in different regions.
Daniel McGrath, a research geophysicist with the program, said much of the government’s ongoing climate research draws from the USGS’s 50 years of Alaska glacier studies.
“Detailed and continuous records of this length are exceedingly rare in our field, and thus these are indispensable to our understanding of the changes we’re observing across this region.”
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. E&E provides daily coverage of essential energy and environmental news at www.eenews.net. Click here for theoriginal story.
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