Nov 30 2016

AK CSC researcher discovers permafrost loss is changing Alaska's Yukon River Basin

By Catherine Puckett, USGS.

Permafrost loss due to a rapidly warming Alaska is leading to significant changes in the freshwater chemistry and hydrology of Alaska’s Yukon River Basin with potential global climate implications. Permafrost loss due to a rapidly warming Alaska is leading to significant changes in the freshwater chemistry and hydrology of Alaska’s Yukon River Basin with potential global climate implications.

Permafrost loss due to a rapidly warming Alaska is leading to significant changes in the freshwater chemistry and hydrology of Alaska’s Yukon River Basin with potential global climate implications.

This is the first time a Yukon River study has been able to use long-term continuous water chemistry data to document hydrological changes over such an enormous geographic area and long time span.

The results of the study have global climate change implications because of the cascading effects of such dramatic chemical changes on freshwater, oceanic and high-latitude ecosystems, the carbon cycle and the rural communities that depend on fish and wildlife in Alaska’s iconic Yukon River Basin.  The study was led by researcher Ryan Toohey of the Department of the Interior’s Alaska Climate Science Center and published in Geophysical Research Letters.

Permafrost rests below much of the surface of the Yukon River Basin, a silent store of thousands of years of frozen water, minerals, nutrients and contaminants.   Above the permafrost is the ‘active layer’ of soil that freezes and thaws each year.  Aquatic ecosystems – and their plants and animals – depend on the ebb and flow of water through this active layer and its specific chemical composition of minerals and nutrients.  

When permafrost thaws, the soil’s active layer expands and new pathways open for water to flow through different parts of the soil, bedrock and groundwater.   These new pathways ultimately change the chemical composition of both surface water and groundwater.

“As the climate gets warmer,” said Toohey, “the thawing permafrost not only enables the release of more greenhouse gases to the atmosphere, but our study shows that it also allows much more mineral-laden and nutrient-rich water to be transported to rivers, groundwater and eventually the Arctic Ocean. Changes to the chemistry of the Arctic Ocean could lead to changes in currents and weather patterns worldwide.” 

Another recent study by University of Alberta scientist Suzanne Tank documented similar changes on another major Arctic river, the Mackenzie River in Canada. With two of these rivers showing striking, long-term changes in their water chemistry, Toohey noted that “these trends strongly suggest that permafrost loss is leading to massive changes in hydrology within the arctic and boreal forest that may have consequences for the carbon cycle, fish and wildlife habitat and other ecosystem services.”

The Domino Effect 

The Yukon River Basin, which is the size of California, starts in northwestern British Columbia, then flows northwest through Yukon across the interior of Alaska to its delta, where it discharges into the Bering Sea. Eventually, its waters reach the Arctic Ocean; it is one of six major rivers that play an important role in the circulation and chemical makeup of the Arctic Ocean.

The new study, which analyzed more than 30 years of data, sheds light on how climate change is already affecting this system. The study specifically found that the Yukon River and one of its major tributaries, the Tanana River, have experienced significant increases in calcium, magnesium and sulfate over the last three decades.

Permafrost rests below much of the surface of the Yukon River Basin, a silent store of thousands of years of frozen water, minerals, nutrients and contaminants. Above the permafrost is the active layer of soil that freezes and thaws each year. Aquatic ecosystems – and their plants and animals – depend on the ebb and flow of water through this active layer and its specific chemical composition of minerals and nutrients.

When permafrost thaws, the soil’s active layer expands and new pathways open for water to flow through different parts of the soil, bedrock and groundwater. These new pathways ultimately change the chemical composition of both surface water and groundwater.

The study was the result of a unique collaboration between the USGS, the Yukon River Inter-Tribal Watershed Council, the Pilot Station Traditional Council and the Indigenous Observation Network funded by these organizations and the Administration for Native Americans and the National Science Foundation.  ION is a citizen-science network that depends on Alaska Native Tribes and First Nations along the Yukon River and its tributaries to participate in scientific research. 

About the Study

The study was the result of a unique collaboration between the USGS, the Yukon River Inter-Tribal Watershed Council, the Pilot Station Traditional Council and the Indigenous Observation Network funded by these organizations and the Administration for Native Americans and the National Science Foundation.  ION is a citizen-science network that depends on Alaska Native Tribes and First Nations along the Yukon River and its tributaries to participate in scientific research.

The original news story can be found online at USGS.