WILDFIRES, DEFORESTATION, LAND USE CHANGE

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WILDFIRES, DEFORESTATION, LAND USE CHANGE
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TOPICS FOR TODAY

• Biomass Burning a source of gases and particles
• How are wildfires changing?
• Can we predict wildfires? What is the possible
  impact?
• Natural land use change
• Anthropogenic land use change

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IS A BIOMASS BURNING NATURAL OR ANTHROPOGENIC?
Perhaps the answer depends on the type of
fire NATURAL ANTHROPOGENIC wildfires land
-clearing / slash burn savannah
burning savannah burning (possibly see
above?) biofuels / residential fuels
BUT, people usually call it one or the othernote
that these categories are important for radiative
forcing (vs. effect)
Types of fires may also be related to (1) fuel
type (2) burn temperature / modified combustion
efficiency
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BIOMASS BURNING A SOURCE OF GASES AND PARTICLES

• BB is an important primary source of
• CO2
• 12-35 ppm of increase from 1850 to 2000
• 1990s 1.6 GtC/yr (compared to 6.4 GtC/yr from
  FF)
• CO 1/4 of total source
• hydrocarbons (incl CH4)
• NOx 15 of total source
• OC 20-60
• BC 2/3
• ? Indirectly important for trop O3

NET radiative forcing 0.03 W/m2
Sometimes biomass burning and land use change
are referred to interchangeably whats the
difference?
IPCC, 2007
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FIRES DEGRADE VISIBILITY
Hayman fire (June 8-22, 2002) worst air quality
ever in Denver ? 56,000 ha (30 miles from
Denver and Colorado Springs)
June 8, 2002
June 9, 2002
PM10 372 µg/m3 PM2.5 200 µg/m3
PM10 40 µg/m3 PM2.5 10 µg/m3
Colorado Department of Public Health and
Environment Vedal et al., Env Res, 2006
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BOREAL REGION LARGE SOURCE OF EMISSIONS
(WILDFIRES)
In 2004, a blocking ridge set up over Canada and
Alaska creating one of the largest fire seasons
on record. In this event, ozone in Houston was
the highest for the past four July months

• Emissions can be large from boreal regions
  (Canada, Alaska, Siberia) because
• Largely unpopulated/unchecked fires (duration,
  extent)
• Dense vegetation (fuel load)
• Hot fires (complete burn)
• Rich understory, organic soil layer (fuel load)

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LONG-RANGE TRANSPORT OF BOREAL EMISSIONS CAN ALSO
AFFECT LOWER 48 STATES
http//asl.umbc.edu/pub/mcmillan/www/index_INTEXA.
html
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EFFECTS OF DISTURBANCE
Biscuit Fire in Oregon (summer 2002)
A fire first releases a pulse of carbon and then
reduces the albedo of a surface from 15 to 20 to
around 4. The blackened surface absorbs much
more incident solar energy, and with little live
vegetation remaining for evaporative cooling,
midday surface temperatures can easily reach
50C. Albedo may recover from resprouting
vegetation within a few months in a tropical
grassland, but require decades in a boreal
forest.
Running, 2008
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TOPICS FOR TODAY

• Biomass Burning a source of gases and particles
• How are wildfires changing?
• Can we predict wildfires? What is the possible
  impact?
• Natural land use change
• Anthropogenic land use change

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WILDFIRES DRIVE INTERANNUAL VARIABILITY IN OC
CONCENTRATIONS IN US
Model gives same variability as observed OC in
summer at IMPROVE sites in the West OC
contribution to total fine aerosol 40 in low
fire years 55 in high fire years
same fires every year
Spracklen et al., 2007
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OBSERVED INCREASES IN FIRES IN NORTH
AMERICA(Related to temperature)
Area burned in Canada has increased since the
1960s, correlated with T increase.
Gillett et al., 2004
5 year means
Increased fire frequency over western U.S. in
recent decades related to warmer T, earlier
snow melt.
Westerling et al., 2007
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INCREASED FIRE ACTIVITY RELATED TO TIMING OF
SNOWMELT (ESP. AT ELEVATION)
R0.76
Correlation b/w wildfire frequency snowmelt
timing
Length of fire season increased by 78 days
(between 1970-1986 and 1987-2003). Increase
concentrated between 1680-2590 m elevation (more
susceptible to drought). Greatest increase in
Northern Rockies (accounts for 60).
Westerling et al., 2007
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TOPICS FOR TODAY

• Biomass Burning a source of gases and particles
• How are wildfires changing?
• Can we predict wildfires? What is the possible
  impact?
• Natural land use change
• Anthropogenic land use change

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PREDICTING WILDFIRE FREQUENCY (IN THE WESTERN US)
Wildfires primarily driven by T and precip
develop a statistical model to predict
Annual total biomass consumed by forest fires,
1996-2055
Results show far Future 2040-2050 biomass
consumption by wildfires over the western United
States is 50 greater than for present-day.
Spracklen et al., in press
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PREDICTED CHANGES IN OC/BC
OC (1996-2000)
BC (1996-2000)
Present Day
Delta OC
Delta BC
Change in 50 years
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INCREASED WILDFIRE ACTIVITY LEADS TO INCREASING
OZONE IN W US
JJA surface ozone
2000
Mean of 5 ppbv enhancement due to fires
2051
ppbv
Hudman et al., in progress
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TOPICS FOR TODAY

• Biomass Burning a source of gases and particles
• How are wildfires changing?
• Can we predict wildfires? What is the possible
  impact?
• Natural land use change
• Anthropogenic land use change

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HOW DOES ELEVATED CO2 AFFECT PLANTS?
Cramer et al., 2001
?CO2 ? water use efficiency (reduced stomatal
conductance and transpiration) ? light efficiency
(increased rates of photosynthesis) ? nutrient
use efficiency
Often referred to as CO2 fertilization
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TESTING BIOSPHERIC FERTILIZATION AT FACE
Free-Air CO2 Enrichment (FACE) sites at Duke
Forest

• DeLucia et al., Science 1999
• After 2 years growth rate enhanced by 26 when
  exposed to 200 ppm CO2
• Increased total NPP by 25
• Oren et al., Nature 2001
• Here we present evidence that estimates of
  increases in carbon sequestration
• of forests, , are unduly optimistic.
• ? Issue of soil fertility/nutrient limitation

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FUTURE CHANGES IN BIOME
Note response of high-latitude T changes
Notaro et al., 2007
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IPCC LAND USE MODEL PROJECTIONS
IPCC, 2007 (WG3, Chap 3)
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PREDICTED CHANGES IN VEGETATIONFROM 8 GCMS
?LAI (2100-2000)
Same land model (CLM) driven by 8 different
climate projections ? Very sensitive to precip
mm
Alo and Wang, 2008
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LAND COVER AND LAND USE CHANGE CAN HAVE DRAMATIC
IMPACT ON EMISSIONS
Direct impacts Indirect Impacts
Jiang et al., 2008
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BARK BEETLE INFESTATION IN THE WESTERN NORTH
AMERICA
Exacerbated by climate change
In bad years equivalent carbon source to 75 of
all Canadian fires
Kurz et al., 2008
Christine Wiedinmyer, NCAR

• Killing off forest ecosystems
• Impact on emissions
• Local climate/hydrology/ecology

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TOPICS FOR TODAY

• Biomass Burning a source of gases and particles
• How are wildfires changing?
• Can we predict wildfires? What is the possible
  impact?
• Natural land use change
• Anthropogenic land use change

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TREE PLANTATIONS
Globally, plantations account for 5 of forests
(187 million ha in 2000), with 62 of this in Asia
Plantation Species
Plantation Use
fuelwood, soil water conservation, other
Monocultures often represent a disturbance to the
larger environment, are susceptible to attack,
modify biospheric emissions
UN FAO http//www.fao.org/docrep/004/y2316e/y2316
e0b.htm
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Courtesy of Nick Hewitt
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HUMAN-DRIVEN LAND USE TRANSITIONS
According to current satellite-based estimates,
17 million km2, or 14 of the land surface, has
been changed by human agricultural activity, and
another 28 is used for domestic animal grazing
Running et al., 2008
Foley et al., 2005
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URBANIZATION
Urbanized population by country (2006)
Potential climate impacts? Heat island (IPCC says
negligible so far) Reduced soil
moisture Localization of pollution (cf Brown
Couds) (Effect on food systems, distribution
networks, etc.)
UNICEF State of the Worlds Children Report, 2008
Percentage of population living in urban regions
has increased from 34 to 47 from 1960s to 1990s
according to The World Bank. Large increases
anticipated, particularly in Asia.