Perilous Times and Climate Change
Wildfires: A Symptom Of Climate Change
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's
Terra satellite shows fires around the world. Credit: NASA
by Michael Finneran
Hampton VA (SPX) Sep 29, 2010
This summer, wildfires swept across some 22 regions of Russia,
blanketing the country with dense smoke and in some cases destroying
entire villages. In the foothills of Boulder, Colo., this month,
wildfires exacted a similar toll on a smaller scale.
That's just the tip of the iceberg. Thousands of wildfires large and
small are underway at any given time across the globe. Beyond the
obvious immediate health effects, this "biomass" burning is part of the
equation for global warming. In northern latitudes, wildfires actually
are a symptom of the Earth's warming.
'We already see the initial signs of climate change, and fires are part
of it," said Dr. Amber Soja, a biomass burning expert at the National
Institute of Aerospace (NIA) in Hampton, Va.
And research suggests that a hotter Earth resulting from global warming
will lead to more frequent and larger fires.
The fires release "particulates" - tiny particles that become airborne
- and greenhouse gases that warm the planet.
Human ignition
A common perception is that most wildfires are caused by acts of
nature, such as lightning. The inverse is true, said Dr. Joel Levine, a
biomass burning expert at NASA Langley Research Center in Hampton, Va.
"What we found is that 90 percent of biomass burning is human
instigated," said Levine, who was the principal investigator for a NASA
biomass burning program that ran from 1985 to 1999.
Levine and others in the Langley-led Biomass Burning Program travelled
to wildfires in Canada, California, Russia, South African, Mexico and
the wetlands of NASA's Kennedy Space Center in Florida.
Biomass burning accounts for the annual production of some 30 percent
of atmospheric carbon dioxide, a leading cause of global warming,
Levine said.
Dr. Paul F. Crutzen, a pioneer of biomass burning, was the first to
document the gases produced by wildfires in addition to carbon dioxide.
"Modern global estimates agree rather well with the initial values,"
said Crutzen, who shared the Nobel Prize in Chemistry 1995 with Mario
J. Molina and F. Sherwood Rowland for their "work in atmospheric
chemistry, particularly concerning the formation and decomposition of
ozone."
Northern exposure
Whether biomass burning is on the rise globally is not clear. But it
definitely is increasing in far northern latitudes, in "boreal" forests
comprised largely of coniferous trees and peatlands.
The reason is that, unlike the tropics, northern latitudes are warming,
and experiencing less precipitation, making them more susceptible to
fire. Coniferous trees shed needles, which are stored in deep organic
layers over time, providing abundant fuel for fires, said Soja, whose
work at the NIA supports NASA.
"That's one of the reasons northern latitudes are so important," she
said, "and the smoldering peat causes horrible air quality that can
affect human health and result in death."
Fires in different ecosystems burn at different temperatures due to the
nature and structure of the biomass and its moisture content. Burning
biomass varies from very thin, dry grasses in savannahs to the very
dense and massive, moister trees of the boreal, temperate and tropical
forests.
Fire combustion products vary over a range depending on the degree of
combustion, said Levine, who authored a chapter on biomass burning for
a book titled "Methane and Climate Change," published in August by
Earthscan.
Flaming combustion like the kind in thin, small, dry grasses in
savannahs results in near-complete combustion and produces mostly
carbon dioxide. Smoldering combustion in moist, larger fuels like those
in forest and peatlands results in incomplete combustion and dirtier
emission products such as carbon monoxide.
Boreal fires burn the hottest and contribute more pollutants per unit
area burned.
'Eerie experience'
Being near large wildfires is a unique experience, said Levine. "The
smoke is so thick it looks like twilight. It blocks out the sun. It
looks like another planet. It's a very eerie experience."
In Russia, the wildfires are believed caused by a warming climate that
made the current summer the hottest on record. The hotter weather
increases the incidence of lightning, the major cause of naturally
occurring biomass burning.
Soja said she hopes the wildfires in Russia prompt the country to
support efforts to mitigate climate change. In fact, Russia's
president, Dmitri A. Medvedev, last month acknowledged the need to do
something about it.
"What's happening with the planet's climate right now needs to be a
wake-up call to all of us, meaning all heads of state, all heads of
social organizations, in order to take a more energetic approach to
countering the global changes to the climate," said Medvedev, in
contrast to Russia's long-standing position that human-induced climate
change is not occurring.