Transcript liu-fire

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
The Lower North Fork Fire
• 20 miles west of Denver
on March 26, 2012
• 4140 acres burned
• 27 home destroyed
• 3 fatalities
• About 400 firefighters
from several states
• A prescribed burning by
Colorado Forest Service
escaped into a wildfire
Warm winds and highs in the 70s are expected to further dry out brush and other
potential fire fuel along the Front Range and Colorado plains., and residents are
being discouraged from lighting campfires or burning trash (NWS).
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
Wildfire in the U.S.
Hundreds of thousands of fires
each year
4 million acres (16,000 km2)
burned annually in past 50 years.
6 million acres in past decade
Low frequency and high severity
in the west, high frequency and
low severity in the east
http://www.fs.fed.us/fire/fuelman/
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
Fire Potential and Fire Danger
Prevent activities
leading to fire
ignition
Fire management
planning (e.g.,
suppression)
Condition for
prescribed
burning
What is fire potential in future under
changing climate?
Atmospheric condition is one of
environmental factors for individual
wildfires
Climate models have projected overall
increase in temperature and more
frequent droughts in many mid-latitude
regions due to the greenhouse effect.
Thus, 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)
Prediction of future U.S. wildfire
trends and 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
Special values of NARCCAP Data
1. Calculating fire danger rating and fire indices such as Keetch-Byram
Drought Index (KBDI)
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
• Wildfires emit large amounts of
PM2.5 and O3 precursors that lead to
regional haze, smog, and visibility
degradation
Smoke prediction system for air quality prediction
(NOAA ARL).
• Biomass burning contributes to
about 40% of total BC emissions,
which play a key role in the smokesnow feedback mechanism.
• Radiative forcing of smoke particles
reduces surface temperature, cloud
and precipitation. Fire events could
enhance climate anomalies such as
droughts.
• Simulations using regional air quality
models such as CMAQ and WRF-Chem
need full meteorology.
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 lines of KBDI 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
Fire potential increases by one level, from low to moderate or
from moderate to high in southern eco-regions
Change in KBDI calculated using HadCM3 projection
Also most remarkable during summer and fall seasons, but with different
spatial patterns.
Future change in southern fuel loading
(Zhang et al., 2009)
Future change in fuel moisture
Change in burning window for prescribed burning
• Available days for
burns are reduced in
most areas.
• Largest reduction in
southeast by up to
30% during summer.
• Increase slightly in
the west coast and
inter-mountains.
Conclusions
• Climate is the most important environmental factor for longterm 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
adds values to traditionally used statistical downscaling by
providing unique information for integrated fire projection and
impact research.
• With the application of NARCCAP data, 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.
Thanks!