June 21 2015 was this year’s Summer Solstice. But for much of Alaska the long hours of sunlight were obscured by smoke. The Sockeye Fire near Willow Alaska started Sunday and raged, burning over 7,000 acres, forcing evacuations, ravaging homes and other structures and interrupting traffic on the Parks Highway. An admirable firefighting effort involving coordination between multiple agencies managed to contain the blaze. Yet the work is far from over. Hundreds of other wildfires are raging in the state of Alaska encouraged by hot, dry and windy conditions.
Scott Rupp, professor of forestry at the University of Alaska Fairbanks, works to understand how fire, vegetation, drought, and climate interact and govern fire behavior. “The biggest factor in terms of the changes that we’re seeing in the fire regime particularly in the last two decades I think is directly correlated to this change in surface air temperatures,” Rupp said.
Watch Frontier Scientists video Fire In Alaska featuring Scott Rupp, professor of forestry, University of Alaska Fairbanks, and Jennifer Barnes, fire ecologist, National Park Service in Alaska.
Rupp explained, “Statistically we find that changes in June and July temperatures are most directly correlated with the increase in cumulative area burned across the state of Alaska.”
Dry springs with hot temperatures like the one this year lead to a lot of fire activity. NOAA’s climate.gov reported that on May 23 2015 a new statewide record was set in Alaska for the earliest day in the year with a temperature in the 90s. The record 91°F was recorded in Eagle, Alaska, where average daily high temperatures in May normally measure 30.1° cooler. An image of Alaska measured by NOAA’s Real-time Mesoscale Analysis data shows air temperatures 6.6 feet [2 meters] above the ground. The red shows temperatures very different from Eagle’s May average daily high of 59.5°F.
The spring’s early high temperatures coupled with extremely low humidity to create fire-ripe conditions. Fallen branches, shrubs, grasses, lichens and mosses, and other old organic material that can be found layered below black spruce stands dry out in the high temperatures and low humidity. An Alaska Fire Orientation video produced by the Bureau of Land Management Alaska Fire Service and State of Alaska Department of Natural Resources, Division of Forestry noted: the drier the organic layer, the deeper the fire will burn.
This decomposed organic material layering the surface is called duff, and– unfortunately– it’s excellent at retaining heat and fostering flames. The Sockeye Fire Facebook Page created to display official fire information notifies Sockeye residents that even after suppression efforts have been completed and the fire is out, they need to remain vigilant against flare-ups.
Out: Is determined when there are no visible or detectable smokes, flames, or hot spots. This may take months or years depending on the fuel type. Given the characteristics of the Tussock Tundra it’s anticipated there will be heat in the duff layer of the tundra for a long time, which may flaire [sic] up into flames periodically during hot, dry and high wind conditions.
Hot conditions with scarce precipitation help flames on the ground climb low vegetation and tree branches (‘ladder fuels’) to reach treetops where they set crown fires. Wind drives smoke and heat forward, drying fuels ahead of the fire’s path and pushing the fire to spread. It can even make the fire jump across open stretches like the Parks Highway. I’ve heard black spruce called gasoline on a stick.
“It’s all about the fuels…” said Rupp. “Temperature directly affects the moisture content of these fuels so warmer temperatures are going to reduce fuel moisture and make things a lot more readily burnable.”
Heat and dry conditions present during high-pressure systems also tend to create gusty warm winds called Chinook winds. In conditions like this years’, both human-made sparks and lightning strikes set fires. The Alaska Interagency Coordination Center’s Fire Information Map | AICC shows over 240 active fires in Alaska at the time of this posting. People are asked to be fire-wise and avoid fire-starting activities like setting off fireworks or setting campfires.
Information provided by the Alaska Interagency Coordination Center and the Alaska DNR- Division of Forestry shows year-to-date wildland fires logged in Alaska 2015. As of June 23rd 2015 there have been 504 fires logged which in total burned 328,124.2 acres; there are 243 active fires burning. That’s a fierce start to the year. For perspective, Rupp stated: “From 1970 to 2000, a 30-year period of time, we burned 20 million acres. From 2000 to 2010 in just a third of that time we burned an additional 20 million acres, so things really seem to be ramping up.”
It’s a dynamic and challenging condition for firefighting personnel, who are facing other Alaskan fires: the Card Street fire, Chisana River 2 fire, Fish Creek fire, Juneau Lake fire, Kobe fire, Long Lake fire, Rex Complex fire, Stetson Creek fire, and more. The Alaska Interagency Coordination Center provides a current fire report which can be found at http://fire.ak.blm.gov/content/aicc/sitreport/current.pdf.
Laura Nielsen 2015
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