Alaska’s changing ice: shrinking glaciers in Skagway, less sea ice in Nome

Skagway sits among glaciers and Nome sits on the Bering Sea ice, and in both places residents say the ice is changing in ways they can see. This National Park Service article, part of a series called Observing Change in Alaska's National Parks, links Klondike Gold Rush National Historical Park and Bering Land Bridge National Preserve through what people there have noticed. It draws on residents' own accounts, paraphrased here.

Harding Glacier near Skagway. Photo from the National Park Service's page.

Skagway: glaciers that are shrinking

Winter conditions often last over six months in parts of Alaska, and ice and snow dominate the landscape. Around Skagway, ice appears as high mountain glaciers and frozen lakes and rivers; glaciers lie in the mountains above White Pass, along the Chilkoot Trail and across Taiya Inlet and Lynn Canal. Warming temperatures are melting and receding them: surface ice turns to water in warm summers, and the glaciers shrink without the heavy winter snow that builds new layers. The glacier on Mount Harding, visible across the inlet from downtown, is a touchstone for residents, who described watching big chunks fall off it and calling it a little glacier that is disappearing.

More meltwater, mixed with more rain and snow, fills the Taiya and Skagway Rivers with more water than before. That can cause local seasonal flooding and bank erosion, can contribute to sea level rise, and changes water chemistry in ways that harm the plants and animals of fragile river ecosystems. A resident said floods have become a little more frequent because more glacial melting feeds the rivers.

The West Creek flood

In July 2002 the water level in West Creek, which flows out of West Creek Glacier into the Taiya River, rose very high and very suddenly, flooding homes and roads in Dyea. People were evacuated, large sections of riverbank eroded and the heavy flow shifted the river's main channel. Scientists found that a rockslide had dropped large boulders into the lake at the bottom of the glacier, pushing a large volume of water over the lake's edge. They found little direct link to glacial melting, though other environmental changes may have made a slide more likely. Residents nonetheless connect the flood to melting and climate change; one pointed out that the glacier had receded and left a lake, and that nothing like it had happened before.

Nome: less sea ice

Arctic ice floes and melt ponds. Image from NOAA.

In Nome, change in sea ice is one of the top climate change issues. Residents describe thinner ice with less of it, going out earlier and forming much later, so winter is shorter. One longtime resident recalled huge pressure ridges forming east to west when young, and icebergs as big as a house in Norton Sound; the last multi-year iceberg stranded on the beach in Nome was seen in the early 1960s.

Blocks of sea ice piled along the shoreline in front of Nome. Photo from the National Park Service's page.

The greatest concern in the Bering Sea is coastal erosion. Shorefast ice acts as a barrier against storm surges, and without it, or without ice that is present long enough or thick enough, waves and wind pushing water against unarmored sand erode the coast and worry communities that once relied on that protection.

Bering Sea storm near Nome. Photo from the National Park Service's page.

An ecosystem that depends on ice

Ice is a key part of the Bering Sea ecosystem: it helps control wave action, water salinity, ocean temperature and nutrient production. A scientist interviewed described a domino effect: warm air from the south destroys the ice, warm water below weakens it, and waves on thin ice consume it. With the ice gone, water is now very warm through the whole water column and the thermal barrier that separated two ecosystems has dissolved, so animals from the southern Bering Sea are moving north and surviving where they once did poorly.

The article closes by asking readers what water-related changes they have noticed where they live.

Sources

• National Park Service, "Ice Conditions", from the series Observing Change in Alaska's National Parks (https://www.nps.gov/articles/000/akprojjukeiceconditions.htm); rewritten in hubnx's own words.