FAIRBANKS — Climate change has already begun to make life difficult for state transportation managers. And they expect it to become a bigger and more expensive challenge if warming trends continue as predicted.
“With over 6,600 miles of coastline and 80 percent of the state underlaid by ice-rich permafrost, you can certainly imagine we are at the forefront of climate change impacts,” said Mike Coffey, maintenance and operations chief for the Alaska Department of Transportation and Public Facilities.
Coffey discussed the impact of climate change on transportation in a webinar last week, hosted by the Alaska Center for Climate Assessment and Policy at the University of Alaska Fairbanks. New challenges include warming permafrost, coastal erosion and the potential for more dramatic storms and flooding, he said. These could lead to more highways and facilities cracking, icing up or even washing away. The hardest-hit areas are northern, western and Interior Alaska, where roads and structures are built over permafrost and near the coast.
Climate data show Alaska has warmed in the past century and is likely to continue warming. Some regions and seasons will experience more warming than others, according to UAF climate research. The research, by Scenarios Network for Alaska Planning, projects average monthly temperatures for different communities using international climate models and predicted greenhouse gas levels. In Fairbanks, for example, the average January temperature climbed approximately three degrees from the late 1990s to this past decade. It’s projected to go up about two more degrees in the next two to three decades.
Climate change looks more dramatic in a place like Newtok, a Yupik village on the west coast of Alaska. Average January temperatures rose about six degrees from the 1960s to last decade. They are projected to climb another two to three degrees by 1940 and approximately five additional degrees by 2060.
The effects of warming
Melting permafrost is the biggest challenge for roads and infrastructure, Coffey said.
“Permafrost is essentially a function of average annual temperature. If average annual temperature goes above the freezing point, eventually you’ll see changes,” said Nancy Fresco, coordinator at Scenarios Network for Alaska Planning.
In most of the nation, roads deteriorate when pavement wears out. But in Alaska, permafrost often gets them first.
Melting permafrost causes pavement to sink and often crack.
“Gravity tends to move material down to fill the void, and we get a depression in the road,” Coffey said.
Severe melting can make roads as wavy as ribbons, as seen on sections of Goldstream and Chena Hot Springs roads.
“This increases maintenance costs and impacts the DOT budget,” Coffey said.
The state spends roughly $11 million per year dealing with permafrost-affected roads and has for about eight years, he said.
The more remote the infrastructure problems, the more expensive they are to fix. While gravel or crushed aggregate used for reconstruction might cost $20 per yard in Anchorage or Fairbanks, it can cost up to $400 per yard in Newtok or $1,000 per yard in Savoonga, Coffey said.
The freeze-thaw cycle is another enemy.
“We’re expecting those to get worse and expand farther across the state,” he said.
In Fairbanks, fall traditionally turns to winter quickly and temperatures typically remain below the freezing mark until April. But lately, the transition has lasted longer.
“We get snow, and it warms up,” Coffey said.
Irregular warm spells during early winter cause events like the freezing rain storm in November that blanketed Fairbanks in ice.
These events force planners to manage roads differently.
“One thing we’re implementing next winter in Fairbanks is an anti-icing program,” Coffey said. “That’s something that has never had to happen in the Interior before.”
Warmer falls also have delayed sea ice formation along coastlines. Without sea ice protection, waves hammer the shoreline during storms.
“Even without increased storm intensity, just with normal weather patterns, if you lose sea-fast ice you get massive coastal erosion,” Fresco said.
The U.S. Army Corps of Engineers has identified 180 communities in Alaska threatened by erosion, Coffey said.
Newtok, the Yupik village on the west coast of Alaska, is “basically being eaten away by erosion of the shoreline,” Coffey said.
Its dump site and barge landing have already eroded away, and houses are next.
Shishmaref, located on an island in the Chukchi Sea, lost 125 feet of beach in a single storm in 1997, he said.
“Many years ago this would have been unheard of,” he said.
Changing weather patterns
Scientists predict climate change will produce increased storms and flooding in the next 50 years.
You can’t blame specific weather events on climate change, Fresco said.
But Coffey described how increased flooding and storms (if they occur) would impact transportation managers, using recent disasters as examples.
The Yukon ice jam in 2009 was preceded by an extremely cold winter, high snowpack and above-average ice pack in the river.
“In mid to late May, temperatures rose into the 80s. We had this unseasonably hot temperature in the Interior. All of a sudden the ice started moving,” Coffey said.
The flooding of Taylor Highway last summer was triggered by three huge rainfalls (equivalent to a typical year’s worth of rain) in July. The rain set off landslides above and below the road.
The road, and access to Eagle, was shut down for more than a month.
What DOT is doing
Managing the statewide impact of climate change ranges from adjusting plowing strategies to relocating entire communities.
Newtok is moving to an island eight miles away on higher ground. To this end, the state built a barge landing facility and an evacuation road at the new site and it is designing an airport plan. The move is estimated to cost $130 million.
In other areas, DOT has transplanted airports and improved drainage systems on arteries like the Steese and Taylor highways.
And in many places, DOT simply tries to keep permafrost frozen, Coffey said.
This can be achieved by pouring deeper fills for roads to insulate the ground underneath. Engineers might also use larger rocks on highway embankments to allow air to circulate, chilling the ground.
Crews currently plow snow onto the shoulder of roads or runways, which insulates the shoulder and prevents frost from penetrating.
They are experimenting with clearing the shoulders to allow cold to penetrate deeper.
Adapting to the future
Transportation managers are designing new infrastructure that can adapt to future impacts of climate change.
That could mean larger culverts, more bridge spans or siting structures like airports higher, above flood zones.
And, for communities near oceans and rivers, that means making buildings that can be relocated if needed.
Contact staff writer Molly Rettig at 459-7590.