finding 22.3 : rising-permafrost-temperature-effects

Permafrost temperatures in Alaska are rising, a thawing trend that is expected to continue, causing multiple vulnerabilities through drier landscapes, more wildfire, altered wildlife habitat, increased cost of maintaining infrastructure, and the release of heat-trapping gases that increase climate warming.

This finding is from chapter 22 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: A central component of the assessment process was the Alaska Regional Climate assessment workshop that was held September 12-15, 2012, in Anchorage with approximately 20 attendees; it began the process leading to a foundational Technical Input Report (TIR).6e174e7d-28f7-4ce4-9141-c378d82b4f53 The report consists of 148 pages of text, 45 figures, 8 tables, and 27 pages of references. Public and private citizens or institutions were consulted and engaged in its preparation and expert review by the various agencies and non-governmental organizations (NGOs) represented by the 11-member TIR writing team. The key findings of the report were presented at the Alaska Forum on the Environment and in a regularly scheduled, monthly webinar by the Alaska Center for Climate Assessment and Policy, with feedback then incorporated into the report. The chapter author team engaged in multiple technical discussions via regular teleconferences. These included careful expert review of the foundational TIR6e174e7d-28f7-4ce4-9141-c378d82b4f53 and of approximately 85 additional technical inputs provided by the public, as well as the other published literature and professional judgment. These discussions were followed by expert deliberation of draft key messages by the writing team in a face-to-face meeting before each key message was selected for inclusion in the Report. These discussions were supported by targeted consultation with additional experts by the lead author of each message, and they were based on criteria that help define “key vulnerabilities” (Ch. 26: Decision Support).

Description of evidence base: The key message and supporting chapter text summarize extensive evidence documented in the Alaska Technical Input Report.6e174e7d-28f7-4ce4-9141-c378d82b4f53 Technical input reports (85) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input. Previous evidence that permafrost is warming9e5e3d14-8ead-4580-90ce-fc5549cc4c47 has been confirmed and enhanced by more recent studies.6a2437ca-35ac-44c4-bd6d-f38b69efdd6a 5a612de8-a07d-48c0-a7ca-c4b705157070 The most recent modeling efforts (for example, Avis et al. 2011; Jafarov et al. 2012622eec71-9cca-4231-949d-a24ac34f45fa 85521935-98c8-4946-a895-6dc3e3dce4d7) extend earlier resultsb5c9b9f8-3f13-4cb6-b4d6-e0b44cfe34c9 4920e8b8-02c6-48d6-9bb7-d466fda80871 and project that permafrost will be lost from the upper few meters from large parts of Alaska by the end of this century. Evidence that permafrost thaw leads to drier landscapes40707b8e-1def-49f8-bc7c-75355ef5a597 2db000de-866a-4a94-96d9-4a778cc81bad is beginning to accumulate, especially as improved remote sensing tools are applied to assess more remote regions.622eec71-9cca-4231-949d-a24ac34f45fa Satellite data has expanded the capacity to monitor wildfire across the region, providing additional evidence of wildfire extent.ea92c82d-60a2-47e5-b48e-31b32ae85b6d This new evidence has led to increased study that is beginning to reveal impacts on ecosystems and wildlife habitat, but much more work is needed to understand the extent of natural resilience. Impacts of permafrost thaw on the maintenance of infrastructureab52be13-af0f-4dad-ba10-db328e20159d 269e8640-18d1-4f61-aa0f-55eb3fbea2d2 3800bb8e-2dea-4285-9aaf-42f7eecc3e0d 41fa8b2f-6581-4633-85d8-f7e3d3ff475a 058cd073-9f08-4809-9522-451f48581dbf is currently moderate but rapidly accumulating. Evidence that permafrost thaw will jeopardize efforts to offset fossil fuel emissions is suggestive (Ch. 2: Our Changing Climate).509ac5ff-2189-49aa-b046-4ab9ea19d6ea 0e2a44dc-cf4a-490b-ab13-8f1b8faa3cb7 fcc250cc-66a0-416f-aa0c-400c9d02e458

New information and remaining uncertainties: Important new evidence confirmed many of the findings from a prior Alaska assessment (, which informed the 2009 NCA.e251f590-177e-4ba6-8ed1-6f68b5e54c8a This evidence included results from improved models and updated observational data. The assessment included insights from stakeholders collected in a series of distributed engagement meetings that confirm the relevance and significance of the key message for local decision-makers. Key uncertainties involve: 1) the degree to which increases in evapotranspiration versus permafrost thaw are leading to drier landscapes; 2) the degree to which it is these drier landscapes associated with permafrost thaw, versus more severe fire weather associated with climate change, that is leading to more wildfire; 3) the degree to which the costs of the maintenance of infrastructure are associated with permafrost thaw caused by climate change versus disturbance of permafrost due to other human activities; and 4) the degree to which climate change is causing Alaska to be a sink versus a source of greenhouse gases to the atmosphere.

Assessment of confidence based on evidence: Very high confidence that permafrost is warming. High confidence that landscapes in interior Alaska are getting drier, although the relative importance of different mechanisms is not completely clear. Medium confidence that thawing permafrost results in more wildfires. There is high confidence that wildfires have been increasing in recent decades, even if it is not clear whether permafrost thaw or hotter and drier weather is more important. High confidence that climate change will lead to increased maintenance costs in future decades. Low confidence that climate change has led to increased maintenance costs of infrastructure in recent decades. Very high confidence that ecological changes will cause Alaska to become a source of greenhouse gases to the atmosphere, even though evidence that Alaska is currently a carbon source is only suggestive.

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