By Lizz Giordano –
Low snowfall and a dry spring prompted an early start to making 2015 the second most widespread fire season on record in Alaska. In 2004, the worst season on record, fires consumed 6.6 million acres of forest.
This year, more than 5.1 million acres burned in 770 fires across the tundras and forests of the northernmost state, stretching firefighters and other resources thin. Warming Arctic regions and changing patterns of rainfall may be the cause as glaciers melt and temperatures in Alaska rise faster than in the lower 48 states.
In the last five decades, Alaskans and the country as a whole watched forest fires spike in the frequency and severity of forest fires, which have also resulted in the release of massive amounts of carbon into the atmosphere.
“There is more of a sense of urgency at the start of the [fire] season now,” said Tom Mowry, public information officer for Alaska’s Division of Forestry.
The blazes so overwhelmed the division this summer that firefighters were forced to prioritize which fires to fight, according to Mowry. In a triage approach, fires that were not threatening homes or other important resources were often left to burn. The office also needed to bring in additional firefighters from the lower 48 states to aid in suppressing and controlling the fires. So far this year, the Division of Forestry has spent over $85 million to battle the most expensive fire season yet.
Fire frequency has doubled in Alaska over the past 25 years, said Eric S. Kasischke, professor of geographical sciences at the University of Maryland. He spent the summers of those years in Alaska studying fires.
“Prior to 1990, there were seven large fire years in 40 years, or one large fire season every six years. Since 1990, there have been nine large fire years in 26 years, or one large fire season every 3 years,” said Kasischke.
Three of the top five wildfire seasons in Alaska have occurred since 2004. The U.S. has experienced five of the top 10 worst fire seasons in terms of acreage burned just the last ten years. Federal fire suppression costs have surged more than 500 percent in the last 30 years, tipping the scale at $1.52 billion for 2014 alone.
One theory that could explain the increase in large fire years, is warming in the arctic region causes oscillation or fluctuations of water temps in the oceans which in turn influences atmospheric circulation, according to Kasischke. This can bring high pressure systems with warm, dry air to Alaska, creating conditions conducive for forest fires.
“It’s not so much warming itself, but it’s warming combined with patterns of precipitation that have contributed to the frequency of fires,” said Kasischke.
Average monthly temperatures have risen in Alaska in the last few decades – 3 degrees Fahrenheit overall in the last 60 years, according to Climate Central. Kasischke said Alaska is experiencing greater climate warming than other areas of the U.S., with most of this warming occurring during the winter months.
“A warm early spring that results in a rapid melting of the snowpack can increase early season fire risk, while a cool spring that delays the melting of the snowpack can reduce early season fire risk,” said Kasischke.
Forest fires are a vital component of a healthy ecological landscape and many trees actually need fires to germinate. Much of Alaska is covered in permafrost, and this permanently frozen soil prevents decomposition, storing carbon dioxide. Normal fires burn one-third to one-half through this layer but the permafrost usually rebuilds quickly, storing carbon once more and resulting in no net change to the levels of carbon in the atmosphere. However, during severe fires, two-thirds to the entire permafrost layer can be consumed. The entire layer will not be able to be rejuvenate, resulting in a net increase of carbon into the atmosphere.
“All other factors being equal, a more severe, deeper-burning fire will result in a net transfer of carbon to the atmosphere,” said Kasischke. “If there is a continuing increase in severe fires that burn deeper into the surface organic layer, there will be an increase in warming of frozen soils, which will increase decomposition of soil carbon, releasing more carbon to the atmosphere.”
Kasischke and his colleague Elizabeth Hoy estimated in a journal article that the amount of emissions released from Alaskan fires in 2004, the worst fire season on record in Alaska, was equal to all the emissions from domestic airlines and railroads for 2003 in North America.
Mowry said he sees dramatic weather variations from one year to the next.
“In 2014, we burned 230,000 acres, then it started raining and didn’t stop,” said Mowry. “This year we burned 5.1 million acres. And what’s going to happen next year is anybody’s guess but the trend is toward larger fire seasons earlier and that is what we are preparing for.”
Photo at top:The Aggie Creek Fire is located 30 miles northwest of Fairbanks, Alaska. The fire was started by a lightning strike on Jun. 22, 2015 and has consumed an estimated 31,705 acres. USFS photo.