Monday, 13 June 2016

Unstoppable tundra fires

The embers of last year’s wildfires are coming back with a vengeance
BETHEL – Hidden underground all winter, an unusual number of holdover fires that smouldered for months in Alaska’s deep duff already have reignited this fire season, state forestry officials said Wednesday.

2 June, 2016

Last year was the second-largest fire season on record in Alaska and 2015 “is still smoking,” officials said. One holdover on Sunday sparked the 8,130-acre Medfra fire now burning in remote Southwest Alaska.
Already 16 holdovers have been spotted, most of them on the Kenai Peninsula or Kodiak Island. Holdover fires are ones that firefighters thought were out, but come back to life as conditions dry out and temperatures rise.
Hot spots

Most of them start out as just little hot spots,” said Tim Mowry, the state Division of Forestry public information officer. “The term fire is sort of a misnomer. They are not really fires. They are usually a little bit of smoke coming out of a burned area.”
The count of 16 that have signaled their presence as of Wednesday appears to be extraordinarily high. Some years there are none; some years just a few. There aren’t records on holdovers, though. Mowry said officials may start tracking them year to year.
It also could be the holdovers are more exposed than usual this year, a state fire behavior expert said.
Mushroom lovers drawn to last year’s wildfire burns as prime picking grounds spotted many of the Kenai smoke-ups, Mowry said.

Safety hazard’

Fire officials warn people to be cautious in burned areas and to call in any smoke rising up from the blackened ground.
It is definitely a safety hazard,” Mowry said.
Alaska is prone to wildfires, and the threat may be worsening. Three of the top five fire seasons on record for Alaska have happened in the last 12 years. Fires are burning hotter and the fire season is starting earlier and lasting longer.
Holdovers also are common here, just not so many as this year, because of the deep duff layer of composting moss, twigs, leaves and spruce needles that blankets the forest floor or the rotting organic underlayer of the tundra.
It’s the nature of Alaska and the thick layer of duff that we are talking about,” Mowry said. “It shows you Alaska wants to burn.”

Hard to fight

Once a fire is established, it is very hard to completely douse, said Robert Ziel, the forestry division’s fire behavior analyst.
Fires burrow down and the duff above them absorbs the moisture.
It’s almost like an umbrella over that fire that keeps it insulated and dry,” Mowry said.
Last summer, more than 5.1 million acres burned, the second largest expanse on record, according to the state. That big fire year combined with low snow last winter and a warm dry spring all may have combined to allow more holdovers.
Fire managers send in crews to try and put down holdovers at the perimeter of an already burned area but aren’t as worried about those surrounded by charred land.
Anything that has the capability to reach out and grab unburned fuel is a concern,” Mowry said.

Medfra fire keeps growing

In Southwest Alaska, officials are attributing the big Medfra fire that started Sunday 50 miles northwest of McGrath to a holdover. It was called in as a smoke report in an old burn area, then quickly spread to fresh fuel. A helicopter from McGrath arrived to dump buckets of water on it within an hour, but by then it had spread over an acre. Smokejumpers stationed in McGrath attacked but it kept growing.
Tuesday night, the Medfra fire merged with the smaller Berry Creek fire, combining for an estimated 8,130 acres burned or burning. The two are among three Southwest Alaska holdovers from the Soda Creek fire that burned about 16,500 acres last summer in the same area near the Kuskokwim River.
About 80 firefighters in four crews were working to protect Native allotments and two cabins on Wednesday. White Mountain’s initial attack crew and crews from Lower Kalskag, Upper Kalskag and Nondalton were on the scene.

More holdovers

On the Kenai Peninsula, all but one of the holdovers were found in the burn area of the Card Street fire that scorched almost 8,900 acres last year near Soldotna. The exception was a holdover from the Funny River fire, which burned almost 200,000 acres – two years ago.
There is also a holdover in the Mat-Su from last year’s Sockeye fire.
Here are the five biggest Alaska wildfire seasons on record:
2004: 701 fires, 6.6 million acres
2015: 768 fires, 5.1 million acres
1957: 391 fires, 5 million acres
1939: 200 fires, 5 million acres
2005: 624 fires, 4.6 million acres

Related stories from around the North:

United States: How tundra wildfires could create an unstoppable cycle, Alaska Dispatch News

Warming, fires, warming, fires: How tundra wildfires could create an unstoppable cycle

Yereth Rosen, Alaska Dispatch News 
2007. Anaktuvuk River Fire, North Slope, Alaska. (Alaska Fire Service).2007. Anaktuvuk River Fire, North Slope, Alaska. (Alaska Fire Service).
When lightning sparked a big fire in the tundra of Alaska’s Arctic North Slope nine years ago, scientists were stunned.

The Anaktuvuk River fire grew to more than 400 square miles and burned for months. It was bigger than the cumulative total of all prior North Slope tundra fires dating back to the 1950s.
If Alaska’s warming trend continues, such fires will no longer be so extraordinary, according to a new analysis led by University of Montana researchers.

Increased probability of fires

Their study, published online in the Sweden-based journal Ecography, uses past fire behavior and conditions to calculate probabilities of wildfires in 30-year timespans. If July temperatures average 13.4 degrees Celsius (56.1 degrees Fahrenheit) and moisture levels are relatively low, wildfires will become significantly more frequent, according to the analysis.

The probability that an area will burn increases a lot,” said co-author Philip Higuera, an associate professor of fire ecology at the University of Montana.
The biggest jump in probability of big fires is for areas that don’t typically burn — the usually moist tundra of the North Slope and similar areas in western Alaska. If the 13.4-degree threshold is reached there, the probability calculations predict up to a fourfold increase in wildfire.

Unprecedented’ fire danger

In tundra regions like the North Slope and the Yukon-Kuskokwim Delta, the fire danger will be “unprecedented” compared to the last 6,000 to 32,000 years, the study says.
The Anaktuvuk River fire in the northern Brooks Range foothills might have been a signal of what is to come.
Anaktuvuk River fire, North Slope, Alaska, near the village of Anaktuvuk Pass, in 2007. (Michelle Mack)
The 2007 Anaktuvuk River fire, North Slope, Alaska, near the village of Anaktuvuk Pass. (Michelle Mack)

The 2007 fire was probably the first for that area in 6,500 years, according to scientific evidence examined later, Higuera said. But the wait for the next big burn won’t be nearly as long, according to the evidence gathered in the study.
That’s what the projections suggest, that we would expect to see more of those,” Higuera said.

More frequent fires

By the late part of this century, wildfires will burn more frequently in nearly all of Alaska, the calculations predict; in a wide swath of the state, the probability of fires will more than double by the middle of the century.
In some places — chiefly, the Interior Alaska boreal forest, where fires are already frequent — the increases may be already underway, Higuera said. Several past studies point to that same conclusion, he said.

Fairbanks has already passed the 13.4 degree Celsius threshold for average July temperatures, and Fort Yukon in the eastern Interior region is expected to reach that point by the end of this decade, according to projections by the University of Alaska Fairbanks’ Scenarios Network for Alaska and Arctic Planning — the same set of projections used in the study to calculate future fire probabilities.

Temperature thresholds

In other parts of Alaska, the July temperature threshold is in reach.
Bethel, the biggest community in the Yukon-Kuskokwim region, and Kotzebue in northwestern Alaska, will soon be at the July temperature threshold, even if global greenhouse gas emissions are reduced from current levels, according to the SNAP projections. Farther north, communities like Anaktuvuk Pass and Nuiqsut could have July temperatures averaging above 13.4 degrees by the late part of century, according to the SNAP projections.
While a warming climate primes Alaska for more frequent wildfires, the fires themselves contribute to warming — and create yet more favorable fire conditions.

Smoke effect

Smoke from wildfires has deposited soot particles onto sea ice, which is already fragile for this time of year compared to recent averages. Darkened ice and snow melts faster, further weakening the ice coverage.
NASA last used satellite imagery to track smoke from fires in Alaska and Canada swirling across the Northern Hemisphere, including the Arctic Ocean, and over the Greenland Sea. NASA in 2014 captured satellite imagery of Russian wildfire smoke drifting over the Arctic Ocean. Smoke from Canada’s huge Fort McMurray fire is now clouding the skies in Europe.

Tundra fires are notable for the sequestered carbon they release from the earth in the form of smoke and exposure of subsurface soil. The Anaktuvuk River fire opened a vast swath of tundra, sending carbon into the atmosphere that had been locked in the soil for as long as 50 years, scientists from the University of Alaska Fairbanks and other institutions found and detailed in a 2011 study published in the journal Nature.

Feedback loop

The darkened surface left by tundra fires reduces the ground’s ability to reflect solar energy back into space, a measure called “albedo,” scientists say. It took four years for the area charred by the Anaktuvuk River fire to return to pre-fire albedo levels, says a new study by scientists from the Michigan Tech Research Institute. Even a much-smaller tundra fire in the Brooks Range foothills, the 2012 Kucher Creek fire, reduced albedo, causing solar heat to be absorbed rather than reflected back, says the study, published in the Journal of Geophysical Research Biogeosciences.

That could lead to future warming, possibly in a significant way, the study says.
The University of Montana-led study calculating future frequency is not a forecast for the coming season or for any year in particular, Higuera said. Instead, the study looks at decades-long trends and cycles, he said. More immediate predictions are available in the national wildfire outlook, which forecasts a fairly normal fire season this year for Alaska.

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