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

The Lower North Fork Fire

• 20 miles west of Denveron 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).

• 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

2005 Southern California Fires

Wildfire in the U.S.Wildfire in the U.S.

Hundreds of thousands of fires Hundreds of thousands of fires each yeareach year

4 million acres (16,000 km4 million acres (16,000 km22) ) burned annually in past 50 burned annually in past 50 years. 6 million acres in past years. 6 million acres in past decadedecade

Low frequency and high severity Low frequency and high severity in the west, high frequency and in the west, high frequency and low severity in the eastlow severity in the east

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

Mega-firesMega-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

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 What is fire potential in future under changing climate?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 Prediction of future U.S. wildfire trends and impacts trends and 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 research project supported by the USDA and USDOI

Joint Fire Science Program (JFSP)

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

• Biomass burning contributes to about 40% of total BC emissions, which play a key role in the smoke-snow 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.

Smoke prediction system for air quality prediction (NOAA ARL).

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 lines of KBDI 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

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

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

Change in KBDI calculated using HadCM3 projection

Future change in southern fuel loadingFuture change in southern fuel loading

(Zhang et al., 2009)

Future change in fuel moistureFuture change in fuel moisture

• 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.

Change in burning window for prescribed burning

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

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

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

Thanks!Thanks!