Posted on 11-11-2002

Indonesian Wildfires Accelerated Global Warming
By Cat Lazaroff

The Indonesian wildfires show that attempts to slow the rate of global
warming will have to focus not only on reducing direct human caused carbon
emissions from factories, power plants and vehicle tailpipes, but also on
efforts to stem the unsustainable destruction of massive carbon stores such
as those found in tropical forests and peat bogs.

Wildfires that scorched parts of Indonesia in 1997 spewed as much carbon
into the atmosphere as the entire planet's biosphere removes from it in a
year, shows new research published this week. The fires, which destroyed
thousands of forest acres and left peat bogs smoldering for months,
released as much as 2.6 billion metric tons of carbon - mostly in the form
of the greenhouse gas carbon dioxide (CO2) - into the atmosphere.

A team of scientists led by Susan Page from the University of Leicester in
the United Kingdom attempted to estimate the mount of carbon released by
the 1997 fires, and their potential effects on global warming. In an
article published in the November 7 issue of the journal "Nature," the
researchers conclude that these fires were "a major contributor to the
sharp increase in atmospheric CO2 concentrations detected in 1998.

>From 1997 to 1998, the growth rate of CO2 in the atmosphere nearly doubled,
from an average of 3.2 gigatons per calendar year to 6.0 gigatonnes, the
highest value on record. Most of the carbon released in the Indonesian
fires came not from burning trees but from smoldering peat bogs which lost
between 25 and 85 centimeters (about 10 to 33 inches) of their depth in the
fires. Tropical peatlands form one of the largest land reserves of organic
carbon. Peat is a carbon rich soil made of compacted, decayed vegetation.
Peat bogs like those found in Indonesia normally support lush swamp forests
over peat deposits that can be up to 20 meters (66 feet) thick. But when
forest clearing, drainage and drought begin to dry out these peatlands,
they become susceptible to fire - as was demonstrated during the 1997 El
Niño driven dry season.

Using satellite images of a 2.5 million hectare study area in Central
Kalimantan, Borneo, from before and after the 1997 fires, the researchers
calculates that about 32 percent, or almost 800,000 hectares, of the area
had burned. Peatlands accounted for 91.5 percent of the burned area, or
about 730,000 hectares. "Using ground measurements of the burn depth of
peat, we estimate that 0.19-0.23 gigatonnes (Gt) of carbon were released to
the atmosphere through peat combustion, with a further 0.05 Gt released
from burning of the overlying vegetation," the team wrote in the "Nature"
article. "Extrapolating these estimates to Indonesia as a whole, we
estimate that between 0.81 and 2.57 Gt of carbon were released to the
atmosphere in 1997 as a result of burning peat and vegetation in
Indonesia," an amount equal to between 13 and 40 percent of the average
annual carbon emissions caused by the burning of fossil fuels around the
world. The CO2 released by the fires was more than all the carbon taken up
by all living things on the planet - collectively known as the biosphere -
in a single year.

The 1997 fires were therefore likely responsible for the massive boost in
CO2 emissions seen in 1997-1998 - the largest annual increase in
atmospheric CO2 concentration detected since records began in 1957,
according to the researchers. Indonesia's 1997 and 1998 fire seasons were
massive, destroying about 10 million hectares (38,600 square miles) of
Indonesia's national forests, recognized as one of the world's centers of
biodiversity. More than 20 million people were exposed to breathing
extremely high levels of pollutants known to cause both acute and long term
health effects. Schools and businesses were closed in Malaysia and people
were advised to remain indoors. But the problem did not end with the easing
of the dry El Niño weather pattern. Wildfires, mostly sparked by humans
clearing forest for agriculture, and exacerbated by increased logging in
the years following the fires, caused major problems again in 2000, and
problems may be cropping up again this year.

These fires destroy some of the habitat on which a variety of endangered
species, such as bears, elephants, rhinos, tigers and orangutans, depend.
Birute Galdikas, a primatologist who began her orangutan research in 1971,
said the number of orangutans in Indonesian Borneo has been halved in the
past decade, partly due to the fires as well as logging and mining. But
besides the catastrophic effects that tropical wildfires may have on
biodiversity, researchers must consider the impact that relatively small
areas of fire may have on the planet as a whole, through their
contributions to global climate change.

Natural, undamaged peat swamp forest is "essential to maintain high water
levels, protect the peat carbon store and facilitate future carbon
sequestration from the atmosphere," the researchers conclude. That position
is echoed by an essay that accompanies the "Nature" article, written by two
scientists from the U.S. National Center for Atmospheric Research. The
researchers, David Schimel and David Baker, note that Susan Page and her
colleagues have shown that "abrupt events can have an appreciable effect on
the carbon cycle. "Most observing systems and modeling strategies assume
that, to affect the carbon cycle, processes must occur over thousands of
square kilometers or more," they write. "But especially in areas of high
carbon density, catastrophic events affecting small areas can evidently
have a huge impact on the global carbon balance."

The Indonesian wildfires show that attempts to slow the rate of global
warming will have to focus not only on reducing direct human caused carbon
emissions from factories, power plants and vehicle tailpipes, but also on
efforts to stem the unsustainable destruction of massive carbon stores such
as those found in tropical forests and peat bogs.

If tropical peat forests continue to be destroyed by logging, development
and fire, "there will be a continued release of carbon through
decomposition of the exposed peat surfaces that, in turn, will place this
large carbon store at further risk," write Page and her colleagues.
"Tropical peatlands will make a significant contribution to global carbon
emissions for some time to come unless major mitigation, restoration and
rehabilitation programs are undertaken."