22. Alaska and the Arctic
Transcript Of 22. Alaska and the Arctic
Draft for Public Comment
Chapter 22 – Alaska (v. 11 Jan 2013)
1
22. Alaska and the Arctic
2 Convening Lead Authors
3
F. Stuart Chapin III, University of Alaska Fairbanks
4
Sarah F. Trainor, University of Alaska Fairbanks
5
6 Lead Authors
7
Patricia Cochran, Alaska Native Science Commission
8
Henry Huntington, Huntington Consulting
9
Carl Markon, U.S. Geological Survey
10
Molly McCammon, Alaska Ocean Observing System
11
A. David McGuire, U.S. Geological Survey and University of Alaska Fairbanks
12
Mark Serreze, University of Colorado
13 Key Messages
14
1. Summer sea ice is receding rapidly and is projected to disappear by mid-century.
15
This is altering marine ecosystems and leading to greater ship access, offshore
16
development opportunity, and increased community vulnerability to coastal erosion.
17
2. Most glaciers in Alaska and British Columbia are shrinking, a trend that is expected
18
to continue. This shrinkage contributes 20% to 30% as much to sea level rise as does
19
shrinkage of the Greenland Ice Sheet. Rapid glacier melt in Alaska has implications
20
for hydropower production, ocean circulation patterns, major U.S. fisheries, and
21
global sea level rise.
22
3. Permafrost temperatures in Alaska are rising, a trend that is expected to continue.
23
Thawing permafrost causes multiple vulnerabilities through drier landscapes, more
24
wildfire, increased cost of maintaining infrastructure, and the release of heat-
25
trapping gases that increase climate warming and jeopardize efforts to offset fossil-
26
fuel emissions through carbon management.
27
4. Current and projected increases in Alaska’s ocean temperatures and changes in
28
ocean chemistry are expected to alter the distribution and productivity of Alaska’s
29
marine fisheries, which lead the U.S. in commercial value.
30
5. The cumulative effects of climate change in Alaska strongly affect Native communities,
31
which are highly vulnerable to these rapid changes but have a deep cultural history of
32
adapting to change.
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1 Introduction 2 Alaska is America’s only arctic region. Its marine, tundra, boreal (northern) forest, and rainforest 3 ecosystems differ from most of those in other states and are relatively intact. Millions of 4 migratory birds, hundreds of thousands of caribou, some of the world’s largest salmon runs, a 5 significant proportion of the nation’s marine mammals, and half of the nation’s fish catch are 6 found in Alaska (NMFS 2010).
7 Energy production is the main driver of the state’s economy, providing over 80% of state 8 government revenue and thousands of jobs (Leask et al. 2001). Continuing pressure for oil, gas, 9 and mineral development on land and offshore in ice-covered waters increases the demand for 10 infrastructure, placing additional stresses on ecosystems. Climate also affects hydropower 11 generation (Cherry et al. 2010). Mining and fisheries are the second and third largest industries 12 in the state, with tourism rapidly increasing since the 1990s (Leask et al. 2001). Fisheries are 13 vulnerable to changes in fish abundance and distribution that result from both climate change and 14 fishing pressure. Tourism might respond positively to warmer springs and autumns (Yu et al. 15 2009) but negatively to less favorable conditions for winter activities and increased summer 16 smoke from wildfire (Trainor et al. 2009).
17 Alaska is home to 40% (229 of 566) of the federally recognized tribes in the U.S. (BIA 2012). 18 The small number of jobs, high cost of living, and rapid social change in rural, predominantly 19 Native communities make them highly vulnerable to climate change through impacts on 20 traditional hunting and fishing and cultural connection to the land and sea. Because most of these 21 communities are not connected to the state’s road system or electrical grid, costs are high, and it 22 is challenging to supply food, fuel, materials, health care, and other services. However, Alaskan 23 Native communities have for centuries dealt with scarcity and high environmental variability and 24 thus have deep cultural reservoirs of flexibility and adaptability. Climate impacts on these 25 communities are magnified by additional social and economic stresses.
26 Observed Climate Change 27 Over the past 60 years, Alaska has warmed more than twice as rapidly as the rest of the U.S., 28 with state-wide average annual air temperature increasing by 3°F and average winter temperature 29 by 6°F. This warming involves more extremely hot days and fewer extremely cold days (Stewart 30 et al. 2013; U.S. Global Climate Change Science Program 2008). Because of its cold-adapted 31 features and rapid warming, climate-change impacts on Alaska are already pronounced, 32 including earlier spring snowmelt, reduced sea ice, widespread glacier retreat, warmer 33 permafrost, drier landscapes, and more extensive insect outbreaks and wildfire, as described 34 below.
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1
2
Figure 22.1: Alaska Will Continue to Warm Rapidly
3
Caption: Northern latitudes are warming faster than more temperate regions, and Alaska
4
has already warmed much faster than the rest of the country. Map shows projected
5
changes in temperature (°F), relative to 1971-1999, projected for Alaska in the early,
6
middle, and late parts of this century, if heat-trapping gas emissions continue to grow
7
(higher emissions, A2), or are substantially reduced (lower emissions, B1). (Figure
8
source: Adapted from Stewart et al. 2013)
9 Projected Climate Change 10 Average annual temperatures in Alaska are projected to rise by an additional 2°F to 4°F by the 11 middle of this century. If global emissions continue to increase during this century, temperatures 12 can be expected to rise 10°F to 12°F in the north, 8°F to 10°F in the interior, and 6°F to 8° in the 13 rest of the state. Even with substantial emission reductions, Alaska is projected to warm by 6°F 14 to 8°F in the north and 4°F to 6°F in the rest of the state by the end of the century (Markon et al. 15 2012; Stewart et al. 2013).
16 Annual precipitation is projected to increase, especially in northwest Alaska (Stewart et al. 17 2013). Over the region, the range of model projections for annual precipitation is an increase of 18 11% to 35%, with an average increase of 25% by late this century if global emissions continue to 19 increase (A2). All models project increases in all four seasons (Stewart et al. 2013). However, 20 increases in evaporation due to higher air temperatures and longer growing seasons are expected 21 to reduce water availability in most of the state (Hinzman et al. 2005). The projected 15 to 25 22 day increase in length of the snow-free and frost-free seasons (University of Alaska Fairbanks
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1 2012) could improve conditions for agriculture where moisture is adequate, but will reduce water 2 storage and increase the risks of more extensive wildfire and insect outbreaks across much of 3 Alaska (Kasischke et al. 2010; McGuire et al. 2010). Changes in dates of snowmelt and freeze4 up would influence seasonal migration of birds and other animals, increase the likelihood and 5 rate of northerly range expansion of native and non-native species, alter the habitats of both 6 ecologically important and endangered species, and affect ocean currents.
7 Disappearing Sea Ice
8 Summer sea ice is receding rapidly and is projected to disappear by mid-century. This is 9 altering marine ecosystems and leading to greater ship access, offshore development 10 opportunity, and increased community vulnerability to coastal erosion.
11 Arctic sea ice extent has declined substantially, especially in late summer when there is now only 12 about half as much sea ice as at the beginning of the satellite record in 1979 (Stroeve et al. 2011). 13 The six Septembers with the lowest ice extent all occurred in the past six years. As sea ice 14 declines, it becomes younger and thinner, and therefore more vulnerable to further melting 15 (Stroeve et al. 2011). Models that best match historical trends project seasonally ice-free 16 northern waters by the 2030s (Stroeve et al. 2007; Wang and Overland 2009, 2012). Within the 17 general downward trend in sea ice there will be periods of a decade or more with both rapid ice 18 loss and temporary recovery (Tietsche et al. 2011), making it challenging to predict short-term 19 changes in ice conditions.
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1
2
Figure 22.2: Declining Sea Ice Extent
3
Caption: Average September extent of arctic sea ice in 1980 (second year of record and
4
year of greatest September sea ice extent; outer red boundary), 1998 (about halfway
5
through the time series; outer pink boundary) and 2012 (most recent year of record and
6
year of least September sea ice extent; outer white boundary). September is typically the
7
month when sea ice is least extensive. Inset is the complete time series of average
8
September sea ice extent (Source: NSIDC 2012).
9 Reductions in sea ice increase the amount of the sun’s energy that is absorbed by the ocean. This 10 leads to a self-reinforcing climate cycle, because the warmer ocean melts more ice, leaving more 11 dark open water that gains even more heat. In autumn and winter, there is a strong release of this 12 extra ocean heat back to the atmosphere. This is a key driver of the observed increases in air 13 temperature in the Arctic (Screen and Simmonds 2010; Serreze et al. 2008). This strong warming 14 linked to ice loss can influence atmospheric circulation and patterns of precipitation, both within 15 and beyond the Arctic (for example, Porter et al. 2012). There is growing evidence that this has 16 already occurred (Francis and Vavrus 2012) through more evaporation from the ocean, which
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Chapter 22 – Alaska (v. 11 Jan 2013)
1 increases water vapor in the lower atmosphere (Serreze et al. 2012) and autumn cloud cover west 2 and north of Alaska (Wu and Lee 2012).
3
4
Figure 22.3: Sea Ice Loss Brings Big Changes to Arctic Life
5
Caption: Reductions in sea ice alter food availability for many species from polar bear to
6
walrus, make hunting less safe for Alaska Native hunters, and create more accessibility
7
for Arctic Ocean marine transport. Photographs by Gary Hufford and Carleton Ray;
8
Caleb Pungowiyi; and Patrick Kelley, respectively.
9 With reduced ice extent, the Arctic Ocean is more accessible for marine traffic, including trans10 arctic shipping, oil and gas exploration, and tourism. This facilitates access to the substantial 11 deposits of oil and natural gas under the seafloor in the Beaufort and Chukchi seas, as well as 12 raising the risk to people and ecosystems from oil spills and other drilling and maritime-related 13 accidents. An ice-free Arctic Ocean also increases sovereignty and security concerns as a result 14 of potential new international disputes and increased possibilities for military and commercial 15 marine traffic between the Pacific and Atlantic Oceans (Markon et al. 2012).
16 Polar bears are one of the most sensitive arctic marine mammals to climate warming because 17 they spend most of their lives on sea ice (Laidre et al. 2008). Declining sea ice in northern 18 Alaska is associated with smaller bears, probably because of less successful hunting of ice19 dependent seals (Rode et al. 2010; Rode et al. 2012). Although bears typically give birth to cubs 20 in dens on sea ice, increasing numbers of female bears now come ashore in Alaska in the 21 summer and fall (Schliebe et al. 2008) and den on land (Fischbach et al. 2007). In the western 22 Hudson Bay in eastern Canada, sea ice is now absent for three weeks longer than just a few 23 decades ago, resulting in less body fat, reduced survival of both the youngest and oldest bears 24 (Stirling et al. 1999), and a population now estimated to be in decline (Regehr et al. 2007).
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1 Walrus depend on sea ice as a platform for giving birth, nursing, and resting between dives to the 2 seafloor, where they feed (Fay 1982). In recent years, when summer sea ice in the Chukchi Sea 3 retreated over waters that were too deep for walrus to feed (Douglas 2010), large numbers of 4 walrus abandoned the ice and came ashore. The high concentration of animals results in 5 increased competition for food and can lead to stampedes when animals are startled, resulting in 6 trampling of calves (Fischbach et al. 2009). This movement to land first occurred in 2007 and 7 has happened three times since then, suggesting a threshold change in the ecology of walrus.
8 With the late-summer ice edge located further north than it used to be, storms produce larger 9 waves and more coastal erosion (Markon et al. 2012). At the same time, coastal bluffs that were 10 “cemented” by permafrost are beginning to thaw in response to warmer air and ocean waters and 11 are therefore more vulnerable to erosion (Overeem et al. 2011). Standard defensive adaptation 12 strategies to protect coastal communities from erosion such as use of rock walls, sandbags, and 13 rip-rap have been largely unsuccessful (State of Alaska 2011). Several coastal communities are 14 seeking to relocate to escape erosion but, because of high costs and policy constraints on use of 15 federal funds for community relocation, only one Alaskan village has begun to relocate (Bronen 16 2011; U.S. Government Accountability Office 2009) (See also Ch. 12: Tribal Lands and 17 Resources)
18 Box 1. Living on the Front Lines of Climate Change
19
“Not that long ago the water was far from our village and could not be easily seen from our
20 homes. Today the weather is changing and is slowly taking away our village. Our boardwalks
21
are warped, some of our buildings tilt, the land is sinking and falling away, and the water is
22 close to our homes. The infrastructure that supports our village is compromised and affecting the
23
health and well-being of our community members, especially our children”
24
Alaska Department of Commerce and Community and Economic Development, (2012)
25 Newtok, a Yup’ik Eskimo community on the seacoast of western Alaska is on the front lines of 26 climate change. Between October 2004 and May 2006, three storms accelerated the erosion and 27 repeatedly “flooded the village water supply, caused raw sewage to be spread throughout the 28 community, displaced residents from homes, destroyed subsistence food storage, and shut down 29 essential utilities” (U.S. Army Corps of Engineers 2008a). The village landfill, barge ramp, 30 sewage treatment facility, and fuel storage facilities were destroyed or severely damaged (U.S. 31 Army Corps of Engineers 2008b). The loss of the barge landing, which delivered most supplies 32 and heating fuel, created a fuel crisis. Salt water is intruding into the community water supply. 33 Erosion is projected to reach the school, the largest building in the community, by 2017.
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1
2
Figure 22.4: Newtok, Alaska
3
Caption: Residents in Newtok, Alaska are living with the effects of climate change, with
4
thawing permafrost, tilting houses, sinking boardwalks, and aging fuel tanks and other
5
infrastructure that cannot be replaced because of laws that prevent public investment in
6
flood-prone localities. Photograph by Stuart Chapin, 2012.
7 Recognizing the increasing danger from coastal erosion, Newtok has worked for a generation to 8 relocate to a safer location. However, current federal legislation does not authorize federal or 9 state agencies to assist communities in relocating, nor does it authorize them to repair or upgrade 10 storm-damaged infrastructure in flood-prone locations like Newtok (Bronen 2011). Newtok 11 therefore cannot safely remain in its current location nor can it access public funds to adapt to 12 climate change through relocation.
13 Newtok’s situation is not unique. At least two other Alaskan communities, Shishmaref and 14 Kivalina, also face immediate threat from coastal erosion and are seeking to relocate, but have 15 been unsuccessful in doing so. Many of the world’s largest cities are coastal and are increasingly 16 exposed to climate-induced flood risks (Nicholls et al. 2007).
17 -- end box --
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1 Shrinking Glaciers
2 Most glaciers in Alaska and British Columbia are shrinking, a trend that is expected to 3 continue. This shrinkage contributes 20% to 30% as much to sea level rise as does 4 shrinkage of the Greenland Ice Sheet. Rapid glacier melt in Alaska has implications for 5 hydropower production, ocean circulation patterns, major U.S. fisheries, and global sea 6 level rise.
7 Alaska is home to some of the largest glaciers and fastest loss of glacier ice on Earth (Berthier et 8 al. 2010; Jacob et al. 2012; Larsen et al. 2007), primarily as a result of rising temperatures (for 9 example, Arendt et al. 2009; Arendt et al. 2002; Oerlemans 2005). Loss of glacial volume in 10 Alaska and neighboring British Columbia, Canada currently contributes 20% to 30% as much 11 surplus fresh water to the oceans as does the Greenland Ice Sheet – about 40 to 70 gigatons per 12 year (Jacob et al. 2012; Kaser et al. 2006; Luthcke et al. 2008; Pelto 2011; Pritchard et al. 2010; 13 Van Beusekom et al. 2010), comparable to 10% of the annual discharge of the Mississippi River 14 (Dai et al. 2009). Glaciers continue to respond to climate warming for years to decades after 15 warming ceases, so ice loss is expected to continue, even if air temperatures were to remain at 16 current levels. The global decline in glacial and ice-sheet volume is predicted to be one of the 17 largest contributors to global sea level rise during this century (Meier et al. 2007; Radić and 18 Hock 2011).
19 Water from glacial landscapes is increasingly recognized as an important source of organic 20 carbon (Bhatia et al. 2010; Hood et al. 2009), phosphorus (Hood and Scott 2008), and iron 21 (Schroth et al. 2011) that contribute to the high productivity of nearshore fisheries (Fellman et al. 22 2010; Hood and Berner 2009; Hood et al. 2009; Royer and Grosch 2006).
23 Glaciers supply about half of the total freshwater input to the Gulf of Alaska (Neal et al. 2010). 24 Glacier retreat currently increases river discharge and hydropower potential in southcentral and 25 southeast Alaska but over the longer term might reduce water input to reservoirs and therefore 26 hydropower resources (Cherry et al. 2010).
27 Thawing Permafrost
28 Permafrost temperatures in Alaska are rising, a trend that is expected to continue. 29 Thawing permafrost causes multiple vulnerabilities through drier landscapes, more 30 wildfire, increased cost of maintaining infrastructure, and the release of heat-trapping 31 gases that increase climate warming and jeopardize efforts to offset fossil fuel emissions 32 through carbon management.
33 Alaska differs from most of the rest of the U.S. in having permafrost – frozen ground that 34 restricts water drainage and therefore strongly influences landscape water balance and the design 35 and maintenance of infrastructure. Alaskan permafrost has warmed about 5°F since the mid36 1970s (Osterkamp and Romanovsky 1999; Romanovsky et al. 2010). In Alaska, 73% of land 37 with permafrost is vulnerable to subsidence upon thawing because of its variable-to-high ice 38 content (Jorgenson et al. 2008). Thaw is already occurring in interior and southern Alaska, where 39 permafrost temperatures are near the thaw point (Romanovsky et al. 2010; Romanovsky et al. 40 2010a). Models project that permafrost in Alaska will continue to thaw (Avis et al. 2011; 41 Euskirchen et al. 2006; Lawrence and Slater 2008), and some models project that near-surface
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1 permafrost will be lost entirely from large parts of Alaska by the end of the century (Marchenko 2 et al. 2012).
3
4
Figure 22.5: The Big Thaw
5
Caption: Projections for average annual ground temperature at 3.3-foot (one-meter)
6
depth over time if emissions of heat-trapping gases continue to grow (higher emissions
7
scenario, A2), and if they are substantially reduced (lower emissions scenario, B1). Blue
8
shades represent areas below freezing (where permafrost is present at the surface), and
9
yellow and red shades represent areas above freezing (permafrost-free at the surface)
10
(Markon et al. 2012).
11 Uneven sinking of the ground in response to permafrost thaw is estimated to add between $3.6 12 and $6.1 billion (10% to 20%) to current costs of maintaining public infrastructure such as 13 buildings, pipelines, roads, and airports over the next 20 years (Larsen et al. 2008). In rural 14 Alaska, permafrost thaw will likely disrupt community water supplies and sewage systems 15 (Alessa et al. 2008; Jones et al. 2009; White et al. 2007), with negative effects on human health 16 (Brubaker et al. 2011). The time during which oil and gas exploration is allowed on tundra has 17 decreased by 50% since the 1970s as a result of permafrost vulnerability (Hinzman et al. 2005).
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Chapter 22 – Alaska (v. 11 Jan 2013)
1
22. Alaska and the Arctic
2 Convening Lead Authors
3
F. Stuart Chapin III, University of Alaska Fairbanks
4
Sarah F. Trainor, University of Alaska Fairbanks
5
6 Lead Authors
7
Patricia Cochran, Alaska Native Science Commission
8
Henry Huntington, Huntington Consulting
9
Carl Markon, U.S. Geological Survey
10
Molly McCammon, Alaska Ocean Observing System
11
A. David McGuire, U.S. Geological Survey and University of Alaska Fairbanks
12
Mark Serreze, University of Colorado
13 Key Messages
14
1. Summer sea ice is receding rapidly and is projected to disappear by mid-century.
15
This is altering marine ecosystems and leading to greater ship access, offshore
16
development opportunity, and increased community vulnerability to coastal erosion.
17
2. Most glaciers in Alaska and British Columbia are shrinking, a trend that is expected
18
to continue. This shrinkage contributes 20% to 30% as much to sea level rise as does
19
shrinkage of the Greenland Ice Sheet. Rapid glacier melt in Alaska has implications
20
for hydropower production, ocean circulation patterns, major U.S. fisheries, and
21
global sea level rise.
22
3. Permafrost temperatures in Alaska are rising, a trend that is expected to continue.
23
Thawing permafrost causes multiple vulnerabilities through drier landscapes, more
24
wildfire, increased cost of maintaining infrastructure, and the release of heat-
25
trapping gases that increase climate warming and jeopardize efforts to offset fossil-
26
fuel emissions through carbon management.
27
4. Current and projected increases in Alaska’s ocean temperatures and changes in
28
ocean chemistry are expected to alter the distribution and productivity of Alaska’s
29
marine fisheries, which lead the U.S. in commercial value.
30
5. The cumulative effects of climate change in Alaska strongly affect Native communities,
31
which are highly vulnerable to these rapid changes but have a deep cultural history of
32
adapting to change.
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Chapter 22 – Alaska (v. 11 Jan 2013)
1 Introduction 2 Alaska is America’s only arctic region. Its marine, tundra, boreal (northern) forest, and rainforest 3 ecosystems differ from most of those in other states and are relatively intact. Millions of 4 migratory birds, hundreds of thousands of caribou, some of the world’s largest salmon runs, a 5 significant proportion of the nation’s marine mammals, and half of the nation’s fish catch are 6 found in Alaska (NMFS 2010).
7 Energy production is the main driver of the state’s economy, providing over 80% of state 8 government revenue and thousands of jobs (Leask et al. 2001). Continuing pressure for oil, gas, 9 and mineral development on land and offshore in ice-covered waters increases the demand for 10 infrastructure, placing additional stresses on ecosystems. Climate also affects hydropower 11 generation (Cherry et al. 2010). Mining and fisheries are the second and third largest industries 12 in the state, with tourism rapidly increasing since the 1990s (Leask et al. 2001). Fisheries are 13 vulnerable to changes in fish abundance and distribution that result from both climate change and 14 fishing pressure. Tourism might respond positively to warmer springs and autumns (Yu et al. 15 2009) but negatively to less favorable conditions for winter activities and increased summer 16 smoke from wildfire (Trainor et al. 2009).
17 Alaska is home to 40% (229 of 566) of the federally recognized tribes in the U.S. (BIA 2012). 18 The small number of jobs, high cost of living, and rapid social change in rural, predominantly 19 Native communities make them highly vulnerable to climate change through impacts on 20 traditional hunting and fishing and cultural connection to the land and sea. Because most of these 21 communities are not connected to the state’s road system or electrical grid, costs are high, and it 22 is challenging to supply food, fuel, materials, health care, and other services. However, Alaskan 23 Native communities have for centuries dealt with scarcity and high environmental variability and 24 thus have deep cultural reservoirs of flexibility and adaptability. Climate impacts on these 25 communities are magnified by additional social and economic stresses.
26 Observed Climate Change 27 Over the past 60 years, Alaska has warmed more than twice as rapidly as the rest of the U.S., 28 with state-wide average annual air temperature increasing by 3°F and average winter temperature 29 by 6°F. This warming involves more extremely hot days and fewer extremely cold days (Stewart 30 et al. 2013; U.S. Global Climate Change Science Program 2008). Because of its cold-adapted 31 features and rapid warming, climate-change impacts on Alaska are already pronounced, 32 including earlier spring snowmelt, reduced sea ice, widespread glacier retreat, warmer 33 permafrost, drier landscapes, and more extensive insect outbreaks and wildfire, as described 34 below.
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1
2
Figure 22.1: Alaska Will Continue to Warm Rapidly
3
Caption: Northern latitudes are warming faster than more temperate regions, and Alaska
4
has already warmed much faster than the rest of the country. Map shows projected
5
changes in temperature (°F), relative to 1971-1999, projected for Alaska in the early,
6
middle, and late parts of this century, if heat-trapping gas emissions continue to grow
7
(higher emissions, A2), or are substantially reduced (lower emissions, B1). (Figure
8
source: Adapted from Stewart et al. 2013)
9 Projected Climate Change 10 Average annual temperatures in Alaska are projected to rise by an additional 2°F to 4°F by the 11 middle of this century. If global emissions continue to increase during this century, temperatures 12 can be expected to rise 10°F to 12°F in the north, 8°F to 10°F in the interior, and 6°F to 8° in the 13 rest of the state. Even with substantial emission reductions, Alaska is projected to warm by 6°F 14 to 8°F in the north and 4°F to 6°F in the rest of the state by the end of the century (Markon et al. 15 2012; Stewart et al. 2013).
16 Annual precipitation is projected to increase, especially in northwest Alaska (Stewart et al. 17 2013). Over the region, the range of model projections for annual precipitation is an increase of 18 11% to 35%, with an average increase of 25% by late this century if global emissions continue to 19 increase (A2). All models project increases in all four seasons (Stewart et al. 2013). However, 20 increases in evaporation due to higher air temperatures and longer growing seasons are expected 21 to reduce water availability in most of the state (Hinzman et al. 2005). The projected 15 to 25 22 day increase in length of the snow-free and frost-free seasons (University of Alaska Fairbanks
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1 2012) could improve conditions for agriculture where moisture is adequate, but will reduce water 2 storage and increase the risks of more extensive wildfire and insect outbreaks across much of 3 Alaska (Kasischke et al. 2010; McGuire et al. 2010). Changes in dates of snowmelt and freeze4 up would influence seasonal migration of birds and other animals, increase the likelihood and 5 rate of northerly range expansion of native and non-native species, alter the habitats of both 6 ecologically important and endangered species, and affect ocean currents.
7 Disappearing Sea Ice
8 Summer sea ice is receding rapidly and is projected to disappear by mid-century. This is 9 altering marine ecosystems and leading to greater ship access, offshore development 10 opportunity, and increased community vulnerability to coastal erosion.
11 Arctic sea ice extent has declined substantially, especially in late summer when there is now only 12 about half as much sea ice as at the beginning of the satellite record in 1979 (Stroeve et al. 2011). 13 The six Septembers with the lowest ice extent all occurred in the past six years. As sea ice 14 declines, it becomes younger and thinner, and therefore more vulnerable to further melting 15 (Stroeve et al. 2011). Models that best match historical trends project seasonally ice-free 16 northern waters by the 2030s (Stroeve et al. 2007; Wang and Overland 2009, 2012). Within the 17 general downward trend in sea ice there will be periods of a decade or more with both rapid ice 18 loss and temporary recovery (Tietsche et al. 2011), making it challenging to predict short-term 19 changes in ice conditions.
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1
2
Figure 22.2: Declining Sea Ice Extent
3
Caption: Average September extent of arctic sea ice in 1980 (second year of record and
4
year of greatest September sea ice extent; outer red boundary), 1998 (about halfway
5
through the time series; outer pink boundary) and 2012 (most recent year of record and
6
year of least September sea ice extent; outer white boundary). September is typically the
7
month when sea ice is least extensive. Inset is the complete time series of average
8
September sea ice extent (Source: NSIDC 2012).
9 Reductions in sea ice increase the amount of the sun’s energy that is absorbed by the ocean. This 10 leads to a self-reinforcing climate cycle, because the warmer ocean melts more ice, leaving more 11 dark open water that gains even more heat. In autumn and winter, there is a strong release of this 12 extra ocean heat back to the atmosphere. This is a key driver of the observed increases in air 13 temperature in the Arctic (Screen and Simmonds 2010; Serreze et al. 2008). This strong warming 14 linked to ice loss can influence atmospheric circulation and patterns of precipitation, both within 15 and beyond the Arctic (for example, Porter et al. 2012). There is growing evidence that this has 16 already occurred (Francis and Vavrus 2012) through more evaporation from the ocean, which
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1 increases water vapor in the lower atmosphere (Serreze et al. 2012) and autumn cloud cover west 2 and north of Alaska (Wu and Lee 2012).
3
4
Figure 22.3: Sea Ice Loss Brings Big Changes to Arctic Life
5
Caption: Reductions in sea ice alter food availability for many species from polar bear to
6
walrus, make hunting less safe for Alaska Native hunters, and create more accessibility
7
for Arctic Ocean marine transport. Photographs by Gary Hufford and Carleton Ray;
8
Caleb Pungowiyi; and Patrick Kelley, respectively.
9 With reduced ice extent, the Arctic Ocean is more accessible for marine traffic, including trans10 arctic shipping, oil and gas exploration, and tourism. This facilitates access to the substantial 11 deposits of oil and natural gas under the seafloor in the Beaufort and Chukchi seas, as well as 12 raising the risk to people and ecosystems from oil spills and other drilling and maritime-related 13 accidents. An ice-free Arctic Ocean also increases sovereignty and security concerns as a result 14 of potential new international disputes and increased possibilities for military and commercial 15 marine traffic between the Pacific and Atlantic Oceans (Markon et al. 2012).
16 Polar bears are one of the most sensitive arctic marine mammals to climate warming because 17 they spend most of their lives on sea ice (Laidre et al. 2008). Declining sea ice in northern 18 Alaska is associated with smaller bears, probably because of less successful hunting of ice19 dependent seals (Rode et al. 2010; Rode et al. 2012). Although bears typically give birth to cubs 20 in dens on sea ice, increasing numbers of female bears now come ashore in Alaska in the 21 summer and fall (Schliebe et al. 2008) and den on land (Fischbach et al. 2007). In the western 22 Hudson Bay in eastern Canada, sea ice is now absent for three weeks longer than just a few 23 decades ago, resulting in less body fat, reduced survival of both the youngest and oldest bears 24 (Stirling et al. 1999), and a population now estimated to be in decline (Regehr et al. 2007).
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1 Walrus depend on sea ice as a platform for giving birth, nursing, and resting between dives to the 2 seafloor, where they feed (Fay 1982). In recent years, when summer sea ice in the Chukchi Sea 3 retreated over waters that were too deep for walrus to feed (Douglas 2010), large numbers of 4 walrus abandoned the ice and came ashore. The high concentration of animals results in 5 increased competition for food and can lead to stampedes when animals are startled, resulting in 6 trampling of calves (Fischbach et al. 2009). This movement to land first occurred in 2007 and 7 has happened three times since then, suggesting a threshold change in the ecology of walrus.
8 With the late-summer ice edge located further north than it used to be, storms produce larger 9 waves and more coastal erosion (Markon et al. 2012). At the same time, coastal bluffs that were 10 “cemented” by permafrost are beginning to thaw in response to warmer air and ocean waters and 11 are therefore more vulnerable to erosion (Overeem et al. 2011). Standard defensive adaptation 12 strategies to protect coastal communities from erosion such as use of rock walls, sandbags, and 13 rip-rap have been largely unsuccessful (State of Alaska 2011). Several coastal communities are 14 seeking to relocate to escape erosion but, because of high costs and policy constraints on use of 15 federal funds for community relocation, only one Alaskan village has begun to relocate (Bronen 16 2011; U.S. Government Accountability Office 2009) (See also Ch. 12: Tribal Lands and 17 Resources)
18 Box 1. Living on the Front Lines of Climate Change
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“Not that long ago the water was far from our village and could not be easily seen from our
20 homes. Today the weather is changing and is slowly taking away our village. Our boardwalks
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are warped, some of our buildings tilt, the land is sinking and falling away, and the water is
22 close to our homes. The infrastructure that supports our village is compromised and affecting the
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health and well-being of our community members, especially our children”
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Alaska Department of Commerce and Community and Economic Development, (2012)
25 Newtok, a Yup’ik Eskimo community on the seacoast of western Alaska is on the front lines of 26 climate change. Between October 2004 and May 2006, three storms accelerated the erosion and 27 repeatedly “flooded the village water supply, caused raw sewage to be spread throughout the 28 community, displaced residents from homes, destroyed subsistence food storage, and shut down 29 essential utilities” (U.S. Army Corps of Engineers 2008a). The village landfill, barge ramp, 30 sewage treatment facility, and fuel storage facilities were destroyed or severely damaged (U.S. 31 Army Corps of Engineers 2008b). The loss of the barge landing, which delivered most supplies 32 and heating fuel, created a fuel crisis. Salt water is intruding into the community water supply. 33 Erosion is projected to reach the school, the largest building in the community, by 2017.
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Figure 22.4: Newtok, Alaska
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Caption: Residents in Newtok, Alaska are living with the effects of climate change, with
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thawing permafrost, tilting houses, sinking boardwalks, and aging fuel tanks and other
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infrastructure that cannot be replaced because of laws that prevent public investment in
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flood-prone localities. Photograph by Stuart Chapin, 2012.
7 Recognizing the increasing danger from coastal erosion, Newtok has worked for a generation to 8 relocate to a safer location. However, current federal legislation does not authorize federal or 9 state agencies to assist communities in relocating, nor does it authorize them to repair or upgrade 10 storm-damaged infrastructure in flood-prone locations like Newtok (Bronen 2011). Newtok 11 therefore cannot safely remain in its current location nor can it access public funds to adapt to 12 climate change through relocation.
13 Newtok’s situation is not unique. At least two other Alaskan communities, Shishmaref and 14 Kivalina, also face immediate threat from coastal erosion and are seeking to relocate, but have 15 been unsuccessful in doing so. Many of the world’s largest cities are coastal and are increasingly 16 exposed to climate-induced flood risks (Nicholls et al. 2007).
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1 Shrinking Glaciers
2 Most glaciers in Alaska and British Columbia are shrinking, a trend that is expected to 3 continue. This shrinkage contributes 20% to 30% as much to sea level rise as does 4 shrinkage of the Greenland Ice Sheet. Rapid glacier melt in Alaska has implications for 5 hydropower production, ocean circulation patterns, major U.S. fisheries, and global sea 6 level rise.
7 Alaska is home to some of the largest glaciers and fastest loss of glacier ice on Earth (Berthier et 8 al. 2010; Jacob et al. 2012; Larsen et al. 2007), primarily as a result of rising temperatures (for 9 example, Arendt et al. 2009; Arendt et al. 2002; Oerlemans 2005). Loss of glacial volume in 10 Alaska and neighboring British Columbia, Canada currently contributes 20% to 30% as much 11 surplus fresh water to the oceans as does the Greenland Ice Sheet – about 40 to 70 gigatons per 12 year (Jacob et al. 2012; Kaser et al. 2006; Luthcke et al. 2008; Pelto 2011; Pritchard et al. 2010; 13 Van Beusekom et al. 2010), comparable to 10% of the annual discharge of the Mississippi River 14 (Dai et al. 2009). Glaciers continue to respond to climate warming for years to decades after 15 warming ceases, so ice loss is expected to continue, even if air temperatures were to remain at 16 current levels. The global decline in glacial and ice-sheet volume is predicted to be one of the 17 largest contributors to global sea level rise during this century (Meier et al. 2007; Radić and 18 Hock 2011).
19 Water from glacial landscapes is increasingly recognized as an important source of organic 20 carbon (Bhatia et al. 2010; Hood et al. 2009), phosphorus (Hood and Scott 2008), and iron 21 (Schroth et al. 2011) that contribute to the high productivity of nearshore fisheries (Fellman et al. 22 2010; Hood and Berner 2009; Hood et al. 2009; Royer and Grosch 2006).
23 Glaciers supply about half of the total freshwater input to the Gulf of Alaska (Neal et al. 2010). 24 Glacier retreat currently increases river discharge and hydropower potential in southcentral and 25 southeast Alaska but over the longer term might reduce water input to reservoirs and therefore 26 hydropower resources (Cherry et al. 2010).
27 Thawing Permafrost
28 Permafrost temperatures in Alaska are rising, a trend that is expected to continue. 29 Thawing permafrost causes multiple vulnerabilities through drier landscapes, more 30 wildfire, increased cost of maintaining infrastructure, and the release of heat-trapping 31 gases that increase climate warming and jeopardize efforts to offset fossil fuel emissions 32 through carbon management.
33 Alaska differs from most of the rest of the U.S. in having permafrost – frozen ground that 34 restricts water drainage and therefore strongly influences landscape water balance and the design 35 and maintenance of infrastructure. Alaskan permafrost has warmed about 5°F since the mid36 1970s (Osterkamp and Romanovsky 1999; Romanovsky et al. 2010). In Alaska, 73% of land 37 with permafrost is vulnerable to subsidence upon thawing because of its variable-to-high ice 38 content (Jorgenson et al. 2008). Thaw is already occurring in interior and southern Alaska, where 39 permafrost temperatures are near the thaw point (Romanovsky et al. 2010; Romanovsky et al. 40 2010a). Models project that permafrost in Alaska will continue to thaw (Avis et al. 2011; 41 Euskirchen et al. 2006; Lawrence and Slater 2008), and some models project that near-surface
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1 permafrost will be lost entirely from large parts of Alaska by the end of the century (Marchenko 2 et al. 2012).
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Figure 22.5: The Big Thaw
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Caption: Projections for average annual ground temperature at 3.3-foot (one-meter)
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depth over time if emissions of heat-trapping gases continue to grow (higher emissions
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scenario, A2), and if they are substantially reduced (lower emissions scenario, B1). Blue
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shades represent areas below freezing (where permafrost is present at the surface), and
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yellow and red shades represent areas above freezing (permafrost-free at the surface)
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(Markon et al. 2012).
11 Uneven sinking of the ground in response to permafrost thaw is estimated to add between $3.6 12 and $6.1 billion (10% to 20%) to current costs of maintaining public infrastructure such as 13 buildings, pipelines, roads, and airports over the next 20 years (Larsen et al. 2008). In rural 14 Alaska, permafrost thaw will likely disrupt community water supplies and sewage systems 15 (Alessa et al. 2008; Jones et al. 2009; White et al. 2007), with negative effects on human health 16 (Brubaker et al. 2011). The time during which oil and gas exploration is allowed on tundra has 17 decreased by 50% since the 1970s as a result of permafrost vulnerability (Hinzman et al. 2005).
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