WASHINGTON — The results of new research released by the U.S. Geological Survey have surprised scientists: Alaska is not likely to emit as much carbon this century as they'd previously expected.
The report marks the first statewide inventory of natural sources of carbon emissions and carbon storage. The research has been in the works since 2012, as part of a nationwide effort by USGS to examine carbon storage.
Also for the first time, scientists considered different water bodies such as lakes and wetlands separately, to avoid double-counting. The report relied on as much new field data as possible, collected by scientists from USGS, the Forest Service and Alaska universities, said USGS scientist and report author Zhiliang Zhu.
The results could reassure many who worry that the impacts of already-occurring climate change in Alaska could compromise efforts to curb greenhouse gas emissions.
In recent years, scientists have sounded the alarm on the climate change implications of Alaska's melting permafrost, the frozen layer of soil and rock that covers from one-third to two-thirds of the state. As it melts — far faster than once expected — it releases methane, which is an extremely potent greenhouse gas. And thus, climate change in the Arctic begets more climate change.
But the new peer-reviewed government report released Wednesday found that may not be the case, at least through the year 2100.
"I think it was surprising to us … but it's not inconsistent with global analyses that have been conducted for the permafrost region," said Dave McGuire, one of the report's authors.
That's partly because the simulation models showed more vegetation growth than the scientists expected, and partly because the research was able to draw a more explicit line between the permafrost thaw and the amount of carbon exposed, McGuire said. More than 90 percent of Alaska's total carbon stock is stored in permafrost, according to the USGS.
The report is a big deal because it provides a benchmark for policymakers making plans for managing climate change, with new information on how Alaska may impact those plans, McGuire said. Global climate plans require such information to inform the timing of greenhouse-gas reduction goals, he said, comparing it to planning a retirement budget and taking unknown future costs into account.
Additionally, the report found that forests in Southeast Alaska will capture more carbon going forward, though it is only a small region of the state.
The authors noted that the newly released research results are not all-inclusive. But "this at least provides some basis for policymakers to think about carbon management in the U.S., and how Alaska might alter that," McGuire said.
One major potential source of new greenhouse gas emissions was not included in the report, McGuire noted. The models did not include lakes that form due to thawing ice, and whether they are expected to expand or contract in the coming decades. If the lakes expand dramatically because of thawing ice, then there's a potential for a lot more methane emissions, McGuire said. But if they dry out, or perhaps drain differently because of new channels caused by melting permafrost, they might put off more carbon.
Temperatures are still expected to rise — by as much as 8 degrees Celsius in Arctic and Western Alaska — and wildfires will increase in frequency and extent, according to the report.