A CLOSER LOOK AT THE DRAFT NATIONAL CLIMATE ASSESSMENT: IMPACTS ARE ALREADY PRONOUNCED IN ALASKA

Glacier

[In this series, BNA’s climate blog takes a closer look at U.S. regions covered in the draft National Climate Assessment. In addition to Alaska, regions covered in the assessment include the Southeast and Caribbean, Great Plains, Northeast, Northwest, Midwest, Southwest, and Hawaii and U.S. Affiliated Pacific States.]

Climate change in Alaska, which is melting Arctic sea ice, thawing permafrost, and eroding coastlines is forcing the coastal village of Newtok to relocate to safer ground, according to the draft National Climate Assessment.

But it hasn't been easy, due to the high cost, policy constraints on the use of federal funds for relocation, and federal laws that preclude the use of public investment to replace or upgrade infrastructure, such as roads and sewage treatment plants, in flood-prone areas, the draft found. Several other Alaskan coastal communities face the same predicament.

As detailed in an Energy and Climate Report article published Jan. 11, the draft, released by the National Climate Assessment and Development Advisory Committee, is not yet an official federal document. It will become so once it’s submitted to the National Science and Technology Council sometime this fall. The council is expected to review, modify, and approve a final draft by Jan. 30, 2014.

A national assessment on climate science and climate change impacts is due to Congress every four years under the Global Change Research Act of 1990. However, only two reports have been completed since the law passed, one in 2000 and the other in 2009.

Temperature, Precipitation

According to the draft assessment, temperatures in Alaska have risen twice as rapidly compared to the rest of the United States during the past 60 years, with the average annual temperature increasing by 3 degrees Fahrenheit, except in winter, which has warmed by an average of 6 F.

 By 2050, temperatures in Alaska are projected to rise by an additional 2 F to 4 F.

However, if global greenhouse gas emissions continue to rise, temperatures are expected to increase by 2100 as follows:

• between 10 and 12 F in the North,
• between 8 and 10 F in the interior, and
• between 6 and 8 F in the rest of the state.

Even if emissions are “substantially” reduced, Alaska is projected to warm between 6 to 8 F in the North and between 4 and 6 F in the rest of the state by 2100, according to the draft assessment.

In comparison, the draft estimates that, on average, U.S. temperatures will rise between 2 and 4 F by mid-century under current emission trends.

However, by 2100, the average amount of warming in the United States is expected to be about 3 to 5 F under a scenario involving substantial reductions in emissions after 2050, and 5 to 10 F assuming continued increases in greenhouse gas emissions.

Annual precipitation in Alaska is expected to increase, especially in the Northwest. Annual rainfall is expected to increase 11 to 35 percent, with an average increase of 25 percent by late this century if global emissions continue to increase.

While the draft assessment said all models project increases in precipitation during all four seasons, higher rates of evaporation due to warmer weather and longer growing seasons are expected to reduce water availability in most of the state.

Arctic Sea Ice

By 2050, all Arctic summer sea ice is projected to disappear, according to the draft assessment. Already, only half as much ice exists during the late summer based on satellite records dating back to 1979. In fact, the draft said, the “six Septembers with the lowest ice extent all occurred in the past six years.”

Furthermore, as the Arctic sea ice melts, the dark open water will absorb heat more, creating a “self-reinforcing climate cycle,” the draft found.

However, within the general downward trend, the draft said to expect periods of 10 or more years with both more rapid ice loss and “temporary recovery, making it challenging to predict short-term changes in ice conditions.”

Reduced ice in the Arctic has made the ocean more accessible to shipping, oil and gas exploration, and tourism, the draft found, and also frees up access to “substantial deposits” of oil and natural gas under the seafloor in the Beaufort and Chukchi sea.

On the downside, exploration raises the risks of oil spills and other drilling and maritime-related accidents, the draft said. Other concerns include adverse effects on wildlife, especially marine mammals such as polar bears, and sovereignty and security threats that could arise from international disputes and increased commercial and military marine traffic, the draft said.

Glaciers, Permafrost, Ocean Acidification

While the draft does not include projections for sea-level rise for Alaska and the Arctic region, it found that most glaciers in Alaska, and those in British Columbia, Canada, are continuing to shrink, contributing between 20 and 30 percent as much to sea-level rise as does shrinkage of the Greenland Ice Sheet.

Alaska also is different from the rest of the United State in having permafrost, which continues to thaw, according to the draft, releasing carbon dioxide and methane, a greenhouse gas that is more than 20 times stronger than CO2 in trapping radiation.

In addition to contributing to climate change, the thawing of permafrost leads to a drier landscape making it more prone to wildfires. According to the draft, the annual area burned in Alaska by wildfires is expected to double by 2050 and triple by 2100. 

Furthermore, the draft said 73 percent of land with permafrost is vulnerable to uneven sinking due to its high ice content. Estimates show that uneven sinking land will add between $3.6 billion and $6.1 billion to the cost of maintaining public infrastructure such as buildings, pipelines, and roads, the draft said.

The North Pacific Ocean also is prone to acidification, which is caused by the absorption of atmospheric carbon dioxide. Globally, ocean waters have become 30 percent more acidic, and in the North Pacific Ocean, acidification has already reached "a critical threshold for organisms," during some times of the year.

The draft said increased acidification could potentially have widespread impacts on the marine food web, including Alaska’s fisheries, which lead the United States in commercial value.

Native Alaskans

The cumulative effects of climate change in Alaska strongly affect Native communities, who are dependent economically, nutritionally, and culturally on hunting and fishing for their livelihoods, the draft assessment said.

“The capacity of native peoples to survive for centuries in the harshest of conditions reflects their resilience,” the draft said. “Communities must rely not only on improved knowledge of changes that are occurring, but also on strength from within in order to face an uncertain future.”

However, adaption may not be possible, especially in coastal areas where erosion is destroying infrastructure. “New governance institutions are needed to specifically respond to the increasing necessity for climate change induced relocation,” the draft said.