Projecting future changes in U.S. forest fuel and fire conditions Projecting future changes in U.S. forest fuel and fire conditions using NARCCAP regional climate change scenariosusing NARCCAP regional climate change scenarios

Yongqiang Liu

Center for Forest Disturbance Science

USDA Forest Service, Athens, GA

2012 NARCCAP Users’ MeetingApril 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.Wildfire in the U.S.4 million acres (16,000 km4 million acres (16,000 km22) burned annually in ) burned annually in past 50 years. 6 million acres in past decade.past 50 years. 6 million acres in past decade.

Zybach et al. (2009)

http://www.fs.fed.us/fire/fuelman/

Fire RegimesFire RegimesLow frequency and high severity in the west, Low frequency and high severity in the west, high frequency and low severity in the easthigh frequency and low severity in the east

• 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

2005 Southern California Fires

Social and Economic ImpactsSocial and Economic Impacts

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 smoke-snow feedback mechanism. •The radiative forcing of smoke particles reduces surface temperature, cloud and precipitation. Fire events could enhance climate anomalies such as droughts.

• Wildfires emit large amounts of PM2.5 and O3 precursors that lead to regional haze, smog, and visibility degradation

MODIS images of the east Amazon basin on August 11, 2002 (Koren et al. 2004).

Climate and WildfireClimate and Wildfire

Weather /Weather /

climateclimateWind, Wind,

temperature, temperature,

relative relative

humidity, humidity,

precipitationprecipitation

High temperature, low relative humidity, and lack of High temperature, low relative humidity, and lack of

precipitation can make fire more likely by drying out precipitation can make fire more likely by drying out

the fuels.the fuels.

Wind can push fire spread Wind can push fire spread

FuelsFuels Light or heavy, Light or heavy,

arrangement, arrangement,

fuel Moisturefuel Moisture

The dryer and lighter the fuels the more easily they will ignite. A 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 continuous layer of fuels on the forest floor can aid in the spread of

a fire.a fire.

TopographyTopography Flat or slopes, Flat or slopes,

aspectaspectA fire moves more rapidly up hills. A fire is more likely on A fire moves more rapidly up hills. A fire is more likely on

southern and western aspects which are dryer.southern and western aspects which are dryer.

Atmospheric condition is one of environmental factors for wildfire together with fuel and topography

Drought and Mega-firesDrought and Mega-firesBig fires – Very large burned areasBig fires – Very large burned areasBig impacts – smoke transported to major metro areasBig impacts – smoke transported to major metro areasBig efforts – forest management options for risk Big efforts – forest management options for risk prevention and impact mitigation 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 TX and SE fires. About 4.3 million acres burned.

- Worst ever one-year drought

- 2011 GA/FL Okefenokee fires. About 600,000 acres burned.

- Worst drought in Georgia in a century

Climate Change and Future WildfireClimate Change and Future Wildfire• Climate models have projected overall increase in temperature and more frequent Climate models have projected overall increase in temperature and more frequent droughts in many mid-latitude regions due to the greenhouse effect. droughts in many mid-latitude regions due to the greenhouse effect. • It is likely wildfires will increase in frequency and intensity in these regions It is likely wildfires will increase in frequency and intensity in these regions including the U.S. (IPCC 2007).including the U.S. (IPCC 2007).• The impact of climate change on fire is already occurring (Westerling et al., 2006) The impact of climate change on fire is already occurring (Westerling et al., 2006) and will become more remarkable by middle of this century and will become more remarkable by middle of this century in the western U.Sin the western U.S..

(Spracklen et al. 2009)

Future U.S. mega-fires Future U.S. mega-fires and air quality impactsand air quality impacts

• Project future mega-fire activity Project future mega-fire activity under changing climateunder changing climate

• Assess impacts on air quality in Assess impacts on air quality in major metropolitan areasmajor metropolitan areas

• Help mangers develop forest Help mangers develop forest management options for mitigationmanagement options for mitigation

• A key component is application of A key component is application of the NARCCAP regional climate the NARCCAP regional climate change scenarioschange scenarios

- A research project supported by the USDA and USDOI

Joint Fire Science Program (JFSP)

Applications of NARCCAP Data

1. Calculating fire indices such as Keetch-Byram Drought Index (KBDI)

2007 Okefenokee fires in GA/FL(USFS Wildland Fire Assessment System)

• 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.

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 burning4. 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 projectionUsing HadCM3-HRM3 projection

Region Region PresentPresent FutureFuture

winterwinter springspring summersummer fallfall winterwinter springspring summersummer fallfall

PSPS 0.50 0.50 2.132.13 2.242.24 0.950.95 1.971.97 1.491.49 0.010.01 0.070.07

PWPW 0.43 0.43 0.060.06 0.800.80 0.170.17 0.560.56 1.251.25 1.241.24 1.571.57

SWSW 4.154.15 4.324.32 4.484.48 4.004.00 -1.44-1.44 -1.83-1.83 -0.37-0.37 -0.09-0.09

NWNW 2.582.58 2.832.83 2.392.39 2.682.68 2.612.61 2.032.03 2.872.87 3.343.34

SCSC 2.172.17 0.790.79 4.574.57 4.044.04 -3.56-3.56 -1.18-1.18 1.131.13 0.030.03

NCNC 2.642.64 1.861.86 1.421.42 2.982.98 0.340.34 -0.22-0.22 1.901.90 3.373.37

SESE -0.30-0.30 -0.25-0.25 2.712.71 3.203.20 -2.20-2.20 0.610.61 1.611.61 1.761.76

NENE 1.091.09 0.350.35 1.481.48 2.922.92 -1.37-1.37 0.030.03 2.612.61 1.731.73

USUS 1.951.95 1.641.64 2.772.77 3.033.03 1.111.11 0.400.40 1.381.38 1.491.49

Slopes of fitting linear lines of KBDI variation curves over 30-year periods

• 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

Also most remarkable during summer and fall seasons, but with different spatial patterns.

Change in KBDI calculated using HadCM3 projection

Fire potential increases by one level, from low to moderate or from moderate to high in southern eco-regions

Future change in southern fuel loadingFuture change in southern fuel loading

(Zhang et al., 2009)

Future change in fuel moistureFuture change in fuel moisture

• 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.

Change in burning window for prescribed burning

• 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.

Seasonal change in the South

Conclusions and DiscussionConclusions and Discussion • Climate is the most important environmental factor for long-term wildfire Climate is the most important environmental factor for long-term wildfire variability. Large change in future U.S. wildfire is expected under a changing variability. Large change in future U.S. wildfire is expected under a changing climate.climate.

• High-resolution climate change scenarios are necessary for projection of High-resolution climate change scenarios are necessary for projection of future wildfire trends. Dynamical downscaling is adding values to traditionally future wildfire trends. Dynamical downscaling is adding values to traditionally used statistical downscaling by providing unique information for integrated fire used statistical downscaling by providing unique information for integrated fire projection and impact research.projection and impact research.

• With the application of NARCCAP regional climate change scenarios, we With the application of NARCCAP regional climate change scenarios, we were able to understand the impacts of climate change on U.S. fire potential, 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 forest fuel conditions, and forest management. The data will be further applied to understanding the air quality impacts of changing wildfire.to understanding the air quality impacts of changing wildfire.

• It would help improve our fire projection and impact research by further It would help improve our fire projection and impact research by further understanding the differences between GCM and RCM projections, A2 and understanding the differences between GCM and RCM projections, A2 and other emissions scenarios, and dynamical and statistical downscaling. other emissions scenarios, and dynamical and statistical downscaling. Transient climate simulation and projection would be useful for projection of Transient climate simulation and projection would be useful for projection of forest fuel type changes which usually occur at decadal or longer scales.forest fuel type changes which usually occur at decadal or longer scales.

Thanks!Thanks!