Federal Climate Report Says Alaska Could See Big Changes
FAIRBANKS — Alaska will see a warming trend of 10 degrees or more this century if current levels of greenhouse gas emissions continue, along with shrinking lakes, higher rates of wildfire and increasing permafrost melt.
The research program, which includes the participation of 13 federal departments and agencies, is charged with the task of releasing a new assessment of the national climate every four years. Some of the key Alaska researchers discussed its findings during a teleconference Wednesday, focusing particularly on the effect climate change could have on Alaska this century.
The study concluded that much of the climate change seen in the past 50 years is due primarily to human activity.
Although changes haven’t been uniform in every geographic region of the U.S., patterns are clearly shifting in the U.S., said International Arctic Research Center chief scientist John Walsh. The average length of the frost-free season since 1900 has increased anywhere from five days to 21 days in the Lower 48, depending on the region. The Great Lakes have seen their ice levels decrease by 60 percent since the 1970s, while “heavy precipitation events” have increased throughout the country.
Taken together, changes to permafrost, sea ice, ocean acidity levels and extreme weather events show powerful evidence for ongoing change, Walsh said.
“The picture that’s emerging is a consistent one,” he said.
The draft report looks at four potential scenarios for global greenhouse gas emissions until 2100, with varying outcomes for both the planet and northern regions.
The scenario with the lowest greenhouse gas emissions includes a 4-degree warming trend in Alaska by the end of the century. Walsh said that calls for extreme changes to human behavior, with a 70 percent cut from current greenhouse gas emissions by 2100.
“There was a lot of debate about whether we should even include that, given the likelihood of it even happening,” he said.
A “business as usual” scenario — the worst case of the four scenarios — includes emissions roughly on the current trajectory. It would bring an estimated 10-degree to 15-degree increase in Alaska.
“The future changes will be determined largely by human decisions, what humans do,” Walsh said.
Climate change is expected to be particularly powerful in northern regions such as Alaska, according to the report.
The lowest summer sea ice levels ever recorded in the Arctic Ocean occurred in 2012. Under the most optimistic low-emissions scenario, they’ll stabilize at that level through 2100, said Sarah Trainor, a research assistant professor at IARC, who authored the report’s Alaska chapter with UAF biology professor emeritus Terry Chapin. In the highest emission scenario, ice will vanish completely by the end of the century, according to the report.
That would have huge effects on the marine ecosystem and coastal erosion, while also creating opportunities for transportation and offshore oil and gas exploration.