Federal Coordinating Lead Author:
Stephen T. Gray, U.S. Geological Survey
Chapter Lead:
Carl T. Markon, U.S. Geological Survey (Retired)
Chapter Authors:
Matthew Berman, University of Alaska, Anchorage
Laura Eerkes-Medrano, University of Victoria
Thomas Hennessy, U.S. Centers for Disease Control and Prevention
Henry P. Huntington, Huntington Consulting
Jeremy Littell, U.S. Geological Survey
Molly McCammon, Alaska Ocean Observing System
Richard Thoman, National Oceanic and Atmospheric Administration
Sarah Trainor, University of Alaska Fairbanks
Review Editor:
Victoria Herrmann, The Arctic Institute
Technical Contributors:
Todd Brinkman, University of Alaska Fairbanks
Patricia Cochran, Alaska Native Science Commission
Jeff Hetrick, Alutiiq Pride Shellfish Hatchery
Nathan Kettle, University of Alaska Fairbanks
Robert Rabin, National Oceanic and Atmospheric Administration
Jacquelyn (Jaci) Overbeck, Alaska Department of Natural Resources
Bruce Richmond, U.S. Geological Survey
Ann Gibbs, U.S. Geological Survey
David K. Swanson, National Park Service
Todd Attwood, U.S. Geological Survey
Tony Fischbach, U.S. Geological Survey
Torre Jorgenson, Arctic Long Term Ecological Research
Neal Pastick, U.S. Geological Survey
Ryan Toohey, U.S. Geological Survey
Shad O’Neel, U.S. Geological Survey
Eran Hood, University of Alaska Southeast
Anthony Arendt, University of Washington
David Hill, Oregon State University
Lyman Thorsteinson, U.S. Geological Survey
Franz Mueter, University of Alaska Fairbanks
Jeremy Mathis, National Oceanic and Atmospheric Administration
Jessica N. Cross, National Oceanic and Atmospheric Administration
Jennifer Schmidt, University of Alaska Anchorage
David Driscoll, University of Virginia
Don Lemmen, Natural Resources Canada
Philip Loring, University of Saskatoon
Benjamin Preston, RAND Corporation
Stefan Tangen, University of Alaska Fairbanks
John Pearce, U.S. Geological Survey
Darcy Dugan, Alaska Ocean Observing System
Anne Hollowed, National Oceanic and Atmospheric Administration
USGCRP Coordinators:
Fredric Lipschultz, Senior Scientist and Regional Coordinator
Susan Aragon-Long, Senior Scientist

Alaska

Alaska is the largest state in the Nation, spanning a land area of around 580,000 square miles, almost one-fifth the size of the combined lower 48 United States. Its geographic location makes the United States one of eight Arctic nations. The State has an abundance of natural resources and is highly dependent on oil, mining, fishing, and tourism revenues. Changes in climate can have positive and negative impacts on these resources.9,10,11

As part of the Arctic, Alaska is on the front lines of climate change12,13 and is among the fastest warming regions on Earth (Ch. 2: Climate, KM 7).14 It is warming faster than any other state, and it faces a myriad of issues associated with a changing climate. The retreat of arctic sea ice affects many Alaskans in different ways, such as through changes in fish and wildlife habitat that are important for subsistence, tourism, and recreational activities.15,16 The warming of North Pacific waters can contribute to the northward expansion of marine fish species, ecosystem changes, and potential relocation of fisheries.17 An ice-free Arctic also contributes to increases in ocean acidification (through greater ocean–atmosphere interaction), affecting marine mammal habitat and the growth and survival of fish and crab species that are important for both personal and commercial use.18 Lack of sea ice also contributes to increased storm surge and coastal flooding and erosion, leading to the loss of shorelines and causing some communities to relocate.19

Thawing permafrost, melting glaciers, and the associated effects on Alaska’s infrastructure and hydrology are also of concern to Alaskans. Thawing permafrost has negatively affected important infrastructure, which is costly to repair, and these costs are projected to increase.20,21 Melting glaciers may affect hydroelectric power generation through changes in river discharge and associated changes in reservoir capacity.22 A warming climate is also likely to increase the frequency and size of wildfires, potentially changing the type and extent of wildlife habitat favorable for some important subsistence species.23,24,25 Climate change also brings a wide range of human health threats to Alaskans due to increased injuries, smoke inhalation, damage to vital infrastructure, decreased food and water security, and new infectious diseases.10 The subsistence activities of local residents are also affected, which in turn affects food security, culture, and health.26,27,28,29

The cost of a warming climate is projected to be huge, potentially ranging from $3 to $6 billion, between 2008 and 2030 (in 2008 dollars; $3.3–$6.7 billion in 2015 dollars). There are, however, a number of opportunities for Alaskans to respond to these climate-related challenges, including several tools and guidebooks available to support adaptation planning, with some focused specifically on Indigenous communities.30 While many opportunities exist with a changing climate, economic prospects are not well captured in the literature at this time.

Climate

The rate at which Alaska’s temperature has been warming is twice as fast as the global average since the middle of the 20th century. Statewide average temperatures for 2014–2016 were notably warmer as compared to the last few decades,31,32,33 with 2016 being the warmest on record. Daily record high temperatures in the contiguous United States are now occurring twice as often as record low temperatures. In Alaska, starting in the 1990s, high temperature records occurred three times as often as record lows, and in 2015, an astounding nine times as frequently.34,35

   

Figure 26.1: Observed and Projected Changes in Annual Average Temperature

Figure 26.1: (a) The graph shows Alaska statewide annual average temperatures for 1925–2016. The record shows no clear change from 1925 to 1976 due to high variability, but from 1976–2016 a clear trend of +0.7°F per decade is evident. (b) The map shows 1970–1999 annual average temperature. Alaska has a diverse climate, much warmer in the southeast and southwest than on the North Slope (c) The map shows projected changes from climate models in annual average temperature for end of the 21st century (compared to the 1970–1999 average) under a lower scenario (RCP4.5). (d) The map is the same as (c) but for a higher scenario (RCP8.5). Sources: (a) National Oceanic and Atmospheric Administration and U.S. Geological Survey, (b–d) U.S. Geological Survey.

EXPAND

Statewide annual average temperatures from 1925 to the late 1970s were variable with no clear pattern of change;36 however, beginning in the late 1970s and continuing at least through the end of 2016, Alaska statewide annual average temperatures began to increase, with an average rate of 0.7ºF per decade, (Taylor et al. 2017,37 after Hartmann and Wendler 2005;38 see Figure 26.1). Temperatures have been increasing faster in Arctic Alaska than in the temperate southern part of the state, with the Alaska North Slope warming at 2.6 times the rate of the continental U.S. and with many other areas of Alaska, most notably the west coast, central interior, and Bristol Bay, warming at more than twice the continental U.S. rate.39 The long-term temperature trends, however, include considerable variability from decade to decade. For example, in the early part of the record (1920s to early 1940s), temperatures were moderate statewide, with annual averages generally near the long-term average, but were lower from about 1945 to about 1976 and then increased rapidly in the 1970s and 1980s and again in the mid-2010s (Figure 26.1). These variations are in part consistent with variations in large-scale patterns of climate variability in the Pacific Ocean;40 in particular, Arctic warming in the early 20th century was intensified by Pacific variability (warm and cold anomalies of the Pacific sea surface temperatures).41 Precipitation changes have varied significantly across the state from 1920 to 2012, with long-term trends generally showing no clear pattern of change.39

Projected Temperature and Precipitation Changes

Recent availability of more localized climate information allows for more complete descriptions of the geographical variation in historical trends and climate projections.39,42,43 Using downscaled global climate models43 and the higher scenario (RCP8.5) (see Ch. 2: Climate, Box 2.7 and the Scenario Products section of App. 3),44 more warming is projected in the Arctic and interior areas than in the southern areas of Alaska, and average annual precipitation increases are projected for all areas of the state, with greater increases in the Arctic and interior and the largest increases in the northeastern interior.

Climatic extremes are expected to change with the changing climate. Under a higher scenario (RCP8.5), by mid-century (2046–2065) the highest daily maximum temperature (the hottest temperature one might expect on a given summer day) is projected to increase 4°–8°F compared to the average for 1981–2000. For the same future period (2046–2065), the lowest daily maximum temperature (the highest temperature of the coldest day of the year) throughout most of the state is projected to increase by more than 10°F, with smaller projected changes in the Aleutian Islands and southeastern Alaska. Additionally, the lowest daily minimum temperatures (the coldest nights of the year) are projected to increase by more than 12°F. The number of nights below freezing would likely decrease by at least 20 nights per year statewide, and by greater than 45 nights annually in coastal areas of the North Slope, Seward Peninsula, Yukon–Kuskokwim Delta, Alaska Peninsula, and Southcentral Alaska.45 Annual maximum one-day precipitation is projected to increase by 5%–10% in southeastern Alaska and by more than 15% in the rest of the state, although the longest dry and wet spells are not expected to change over most of the state.45 Growing season length (the time between last and first frosts in a given year) is expected to increase by at least 20 days and perhaps more than 40 days compared to the 1982–2010 average.35 Whether or not this increased growing potential is realized will largely depend on soil conditions and precipitation.


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