Rates and Effects of Climate Warming and Permafrost Thawing in the Yukon River Basin: The Yukon Climate Effects Assessment and Monitoring Network

Permafrost that has been frozen for 10s of thousands of years has begun to thaw in many regions of the Boreal Forest. As a result, large quantities of carbon (C) stored in ancient, frozen organic materials will become vulnerable to decomposition or erosion. The magnitude of the consequences resulting from the release of this carbon, such as accelerating greenhouse gas accumulation in the atmosphere or changes in the nutrient balance of the coastal ocean, are largely unknown. The US Geological Survey (USGS) and the US Forest Service (USFS) are leading a developing consortium of US and Canadian federal agencies, university scientists, and tribal organizations in implementing a monitoring and research strategy for understanding and tracking these changes in Arctic and Sub-Arctic landscapes. The collaboration will link air, water, soil, and forest information across the Yukon River Basin to track and understand regional changes in carbon flux and storage. Research in the watershed during 2000-2005 showed that changes in hydrology (decreased flow) and river water-quality (decreased dissolved organic carbon) are already occurring. Evidence of widespread permafrost thawing and the associated enhanced infiltration of water in the watershed have also been documented. Climate sensitivity and growth rates in the Boreal forest is changing in ways unique during the past few centuries. Preliminary research on C flux to the atmosphere in landscapes with thawing permafrost indicates enhanced methane release associated with the development of "thermo-karst" topography where permafrost has degraded. As part of the YUkon CLimate EFFects Assessment and Monitoring Network (Yu-CLEF), ongoing research on the effects of fire, soil moisture, vegetation, gas flux, and hydrology are being integrated with regional surveys of key indicators of C dynamics and recent advances in remote sensing methodology to project our developing process understanding to the regional scale. The combined, multi-scale dataset will be used to improve and constrain the Terrestrial Ecosystem Model (TEM) and General Ensemble Modeling System (GEMS), which in-turn will be used to estimate C flux and storage in the Yukon River Basin. The Yu-CLEF will provide the first comprehensive look at carbon, water, and energy budgets for the Boreal landscape by using a river basin as a common frame of reference, and will establish a systematic network for multi-scale tracking of environmental change as the northern landscape responds to a changing climate.