Transcript qq - NARCCAP

Projecting future changes in U.S. forest fuel and fire conditions
using NARCCAP regional climate change scenarios
Yongqiang Liu
Center for Forest Disturbance Science
USDA Forest Service, Athens, GA
2012 NARCCAP Users’ Meeting
April 10 – 11, 2012. NCAR, Boulder, CO
• Wildfire and impacts
• Climate and wildfire
• Impacts of climate change
• Application of NACCAP data
• Results
• Conclusions and discussion
Wildfire in the U.S.
4 million acres (16,000 km2) burned annually in
past 50 years. 6 million acres in past decade.
Zybach et al. (2009)
Fire Regimes
Low frequency and high severity in the west,
high frequency and low severity in the east
http://www.fs.fed.us/fire/fuelman/
Social and Economic Impacts
2005 Southern California Fires
• 750,000 acres (3,000 km2) burned
• 22 human lives lost
• 4,000 homes destroyed
• Billions of dollars in damage
• 12,000 firefighters in suppression
• Half of the cost for heat and drought
Environmental Impacts
•2.0 Pg C yr−1 during 1997–2009, 1/3
of total carbon emissions (van der
Werf et al. 2010)
• Biomass burning contributes to
about 40% of total BC emissions,
which play a key role in the smokesnow feedback mechanism.
•The radiative forcing of smoke
particles reduces surface temperature,
cloud and precipitation. Fire events
could enhance climate anomalies such
as droughts.
MODIS images of the east Amazon basin on August
11, 2002 (Koren et al. 2004).
• Wildfires emit large amounts of
PM2.5 and O3 precursors that lead to
regional haze, smog, and visibility
degradation
Climate and Wildfire
Atmospheric condition is one of environmental
factors for wildfire together with fuel and topography
Weather
/climate
Wind,
temperature,
relative
humidity,
precipitation
High temperature, low relative humidity, and lack of
precipitation can make fire more likely by drying out
the fuels.
Fuels
Light or heavy,
arrangement,
fuel Moisture
The dryer and lighter the fuels the more easily they will ignite. A
continuous layer of fuels on the forest floor can aid in the spread of
a fire.
Topography
Flat or slopes,
aspect
A fire moves more rapidly up hills. A fire is more likely on
southern and western aspects which are dryer.
Wind can push fire spread
Drought and Mega-fires
Big fires
– Very large burned areas
Big impacts – smoke transported to major metro areas
Big efforts – forest management options for risk
prevention and impact mitigation
Occurring mostly under drought conditions
-
1988 Yellowstone fires. About
800,000 acres affected
The northern U.S. drought was
among the driest of the 20th
century
-
2011 GA/FL Okefenokee fires.
About 600,000 acres burned.
Worst drought in Georgia in a
century
-
2011 TX and SE fires. About 4.3
million acres burned.
Worst ever one-year drought
Climate Change and Future Wildfire
• Climate models have projected overall increase in temperature and more frequent
droughts in many mid-latitude regions due to the greenhouse effect.
• It is likely wildfires will increase in frequency and intensity in these regions
including the U.S. (IPCC 2007).
• The impact of climate change on fire is already occurring (Westerling et al., 2006)
and will become more remarkable by middle of this century in the western U.S.
(Spracklen et al. 2009)
Future U.S. mega-fires
and air quality impacts
- A research project supported by the USDA and USDOI
Joint Fire Science Program (JFSP)
• Project future mega-fire activity
under changing climate
• Assess impacts on air quality in
major metropolitan areas
• Help mangers develop forest
management options for mitigation
• A key component is application of
the NARCCAP regional climate
change scenarios
Applications of NARCCAP Data
1. Calculating fire indices such as Keetch-Byram Drought Index (KBDI)
• KBDI classification
0-200 (low fire potential),
200-400 (moderate),
400-600 (high),
600-800 (extreme)
• Meteorological variables:
maximum temperature,
daily rainfall,
average annual rainfall.
• Dependent on historic conditions,
more suitable for long-term impact.
2007 Okefenokee fires in GA/FL
(USFS Wildland Fire Assessment System)
2. Driving Dynamic Land Ecosystem Model
DLEM - a process-based terrestrial ecosystem model (Tian et al., 2010)
Project fuel change in fuel loading, which is a factor for fire emissions
3. Driving smoke and air quality models
Simulation of 2007 GA fires with CMAQ
4. Calculating windows for prescribed burning
• Prescribed burning is a management tool for
reducing wildfire risk by removing the
accumulating dead fuels.
• One of management tools for mitigation of
future wildfire increase
• However, there is increasing risk for fire
escaping (a control burning becomes a
wildfire) due to global warming.
Preferred weather conditions for prescribed burning in the southern U.S.:
-
wind speed at 20-foot above the ground of 6-20 mph;
relative humidity of 30-55%;
temperature of <60oF in winter;
fine fuel (1-hour) moisture of 10-20%, and
KBDI of 250-400.
• Large values of over 600 (extreme fire potential) all seasons in the
inter-Mountains
• KBDI increases from winter to fall in the East, up to 500
• Using HadCM3-HRM3 projection
Slopes of fitting linear lines of KBDI variation curves
over 30-year periods
Region
Present
winter
spring
PS
0.50
PW
Future
summer
fall
winter
spring
summer
fall
2.13
2.24
0.95
1.97
1.49
0.01
0.07
0.43
0.06
0.80
0.17
0.56
1.25
1.24
1.57
SW
4.15
4.32
4.48
4.00
-1.44
-1.83
-0.37
-0.09
NW
2.58
2.83
2.39
2.68
2.61
2.03
2.87
3.34
SC
2.17
0.79
4.57
4.04
-3.56
-1.18
1.13
0.03
NC
2.64
1.86
1.42
2.98
0.34
-0.22
1.90
3.37
SE
-0.30
-0.25
2.71
3.20
-2.20
0.61
1.61
1.76
NE
1.09
0.35
1.48
2.92
-1.37
0.03
2.61
1.73
US
1.95
1.64
2.77
3.03
1.11
0.40
1.38
1.49
• Increase in Rocky Mountains all seasons
• Increase in Southeast and Pacific coast in Summer and Fall
• Decrease in the inter-Mountains all seasons in Winter and Spring
Change in KBDI calculated using HadCM3 projection
Also most remarkable during summer and fall seasons, but with different
spatial patterns.
Fire potential increases by one level, from low to moderate or
from moderate to high in southern eco-regions
Future change in southern fuel loading
(Zhang et al., 2009)
Future change in fuel moisture
Change in burning window for prescribed burning
• The portion reduces
in most areas.
• Largest reduction in
southeast by up to 0.3
during summer.
• Increase slightly in
the west coast and
inter-mountains.
Seasonal change in the South
• Largest decrease in during summer and fall and smallest during spring.
• Relative decrease rate is about 30% during winter and 10% during
spring, the two major prescribed burning seasons in the South.
Conclusions and Discussion
• Climate is the most important environmental factor for long-term wildfire
variability. Large change in future U.S. wildfire is expected under a changing
climate.
• High-resolution climate change scenarios are necessary for projection of
future wildfire trends. Dynamical downscaling is adding values to traditionally
used statistical downscaling by providing unique information for integrated fire
projection and impact research.
• With the application of NARCCAP regional climate change scenarios, we
were able to understand the impacts of climate change on U.S. fire potential,
forest fuel conditions, and forest management. The data will be further applied
to understanding the air quality impacts of changing wildfire.
• It would help improve our fire projection and impact research by further
understanding the differences between GCM and RCM projections, A2 and
other emissions scenarios, and dynamical and statistical downscaling.
Transient climate simulation and projection would be useful for projection of
forest fuel type changes which usually occur at decadal or longer scales.
Thanks!