Alaska Science Forum
September 5, 2011
Recovery after world's largest tundra fire raises questions
Article #2080
by Ned Rozell
The great Anaktuvuk River tundra fire of 2007.
Photo by Michelle Mack.
Four summers ago, Syndonia Bret-Harte stood outside at Toolik Lake,
watching a wall of smoke creep toward the research station on Alaska’s
North Slope. Soon after, smoke oozed over the cluster of buildings.
“It was a dense, choking fog,” Bret-Harte said.
The smoke looked, smelled and tasted like what
Bret-Harte has experienced at her home in Fairbanks, but the far-north
version was composed of vaporized tundra plants instead of black spruce
and birch. The 2007 Anaktuvuk River fire, which burned an area the size
of Cape Cod, is the largest fire ever recorded in tundra. It was the
first wildfire in the area since slaves were shoving blocks in place to
create the pyramids in Egypt (about 5,000 years ago).
Bret-Harte and others working at the research station
knew they were witnessing something unusual — or maybe seeing the
future. They found funding to study the burn, and time in their
schedules to get their feet on the black ground. The group of
scientists, led by Michelle Mack of the University of Florida,
collaborated on a study published recently in the journal Nature.
Bret-Harte, a plant specialist, just returned from a
helicopter trip to the site of the big fire. Her close-up images show a
green, lush landscape as the tundra recovers nicely after four summers.
“It’s not back to what it was before — the shrubs are
small,” Bret-Harte said. “But in 10 years it will look pretty similar
over much of the area.”
The new vegetation is photosynthesizing with such vigor
that it is taking up as much carbon dioxide from the air as nearby
tundra that did not burn in 2007, Bret-Harte said. This is quite a
change compared to the staggering amount of carbon the fire added to the
atmosphere four summers ago. The researchers calculated that the smoke
from the 2007 fire spewed about half as much carbon dioxide as all
arctic vegetation in the world sucked in during an average year.
If the tundra burned like that every year, in a flash
the Arctic could turn from a place where carbon dioxide is pulled from
the atmosphere and locked away, to a carbon dioxide generator that would
further warm the world.
“The carbon that was lost in this fire represented
about 30 to 50 years of accumulation in the soil,” Bret-Harte said. “But
if you burned it again now, you’re getting into the deeper, older
carbon. You’d be burning away this bank of carbon stored in the soil
over thousands of years. That would be huge.”
Was the 2007 Anaktuvuk River fire a freakish, one-time
event, or a sign of things to come? Bret-Harte said she doesn’t know,
but she does know the conditions that led to the 2007 event. A lightning
strike ignited the tundra in mid-July. Wet soils and vegetation snuff
most tundra fires, but this one endured because of an exceptionally dry
summer. The fire smoldered for a few months until dry Chinook winds
curled over the Brooks Range in September, fanning the fire to life.
“It burned most of the area in five or six days,” Bret-Harte said.
Though the giant tundra fire of 2007 happened due to a
combination of rare conditions, at least one of those factors is
becoming more common. According to sensors maintained by workers for the
Bureau of Land Management, lightning has struck Alaska’s North Slope
much more frequently lately. From a steady hit rate of a few thousand
lightning strikes from the mid-1980s until the late 1990s, lightning
strikes have jumped to about 20,000 each year in the last decade. More
lightning strikes and warmer summers might change what people know as a
smoke-free northern Alaska.
Bret-Harte wonders, “Is this like a tipping point, moving us to a new regime on the North Slope?”
