CRW Engineering Group, LLC Force main's foundations (left) extend into permafrost. The original's did not (right).

Nothing in a new study on the impact of climate change on Alaska infrastructure and construction surprises Michael Rabe, managing principal of CRW Engineering Group, LLC, Anchorage. The report, released last month by the University of Alaska-Anchorage Institute for Social and Economic Research, predicts that a warming climate could cost the state billions of dollars over the next two decades.

Its authors say public structures, including sanitation and water systems, harbors, power stations, roads and bridges all will break down more quickly as erosion, flooding and thawing cycles intensify. Faster deterioration could boost building and maintenance costs by 20%, or up to $6.1 billion, through 2030.

Rabe says climate change already figures into his work. "We see its impact," he says. CRW's portfolio includes projects in areas of fragile permafrost in western Alaska. Even a one-degree change in average temperature over time can begin to thaw permafrost and impair a foundation. "Ten years ago, you had half-a-dozen freeze-thaw cycles in winter; it's double that now," Rabe says.

Temperature shift softens roadways and stresses water and sewer systems. CRW uses different approaches when working on what Rabe calls unstable ground, including thermo-siphon installation that freezes underlying soils in winter.

University resource economist Peter Larsen, the study's lead author, says the report is the first of its kind in Alaska. Its numbers are preliminary but help to paint a broad picture. "There are a number of different state agencies now getting interested in the impact of climate change, and others that have been looking into it for some time," he says. Larsen says roads, runways, and water and sewer systems will account for most of the higher O&M and construction costs.

Dropping

Scientists say the average temperature in Alaska has risen four degrees in the last 40 years, with warmer air and water temperatures making a difference around the state. In south-central Alaska, the state highway agency has recorded increased road and bridge destruction from sediment load in streams, catastrophic flooding and snow avalanches. Average summer pavement patching of 10 miles per year, at $100,000 per mile, has jumped to 45 miles. The North Slope's winter oil-exploration season has been halved since 2003 due to environmental limits preventing driving on tundra not sufficiently frozen or snow-covered.

Bob Juettner, administrator of Aleutians East Borough, which includes the Bering Sea town of Nelson Lagoon, cites coastal erosion. "The airport runway is just a few feet above sea level. It's not going to take a big change before we have to look at relocating it," he says.

While melting permafrost is collapsing roads, weakening bridges and leaving buildings askew, university engineering professor Orson Smith, a study co-author, says seawalls are being destroyed by more violent winter storms and rising sea levels. "As sea ice recedes, waves reach the coast in winter when they didn't before," he says, adding that the coastal villages of Shishmaref, Kivalina and Newtok are facing immediate economic impacts from climate change.

Shishmaref residents are raising funds to move the community five miles inland. Through the Army Corps of Engineers and Alaska's congressional delegation, the the town has obtained about $23 million for flood control and relocation planning. It needs $180 million to make the move. In a 2003 report, the U.S. Government Accountability Office said Shishmaref is one of at least 184 coastal villages grappling with serious erosion and flooding. A few could be unlivable in 10 to 15 years.

Smith thinks Alaska needs to change its construction practices. "There are alternatives to building shore protection and seawalls, which are expensive to put up and maintain," he says. But engineers can't predict precipitation or impact of a winter storm. "Our tool kit of response is pretty good, but the problem remains knowing what to design for," Smith says. Engineers and climate change scientists will convene in January in Anchorage, as they have for seven years, to discuss impacts.