Wildfire Emission Estimates for 2020

Wildfire Emission Estimates for 2020

Background

California wildfire activity in 2020 was historic in scale. State data reported 500 wildfires totaling approximately 4.2 million acres, two to three times more area than in elevated wildfire activity years 2008, 2017, or 2018 (Figure 1). As in previous active years, a few largearea wildfires comprised most of the year's burned area. Over half of the state total acreage burned was dominated by five fires: August Complex, SCU Complex, Creek, North Complex, and Hennessey. The August Complex was the largest area ever recorded for a single fire event. Large areas and high fuel loads (associated with forested lands) together with dry conditions fostered extensive fuel consumption and large magnitude emissions. California Air Resources Board (CARB) staff used Geographic Information Systems (GIS) based data on wildfire perimeters, vegetation fuels and fuel moisture, burn severity, as inputs to a fire emission model to estimate emissions from all fires in the dataset. Information related to these input data and model can be found in CARB's Technical Documentation1 and answers to frequently asked questions can be found here2.

Emissions Modeling Results

A wildfire's total emissions represents the contribution from the mosaic of vegetation types and fuels consumed within the wildfire area or "footprint". Forest and woodland vegetation types contain greater fuel loads per unit area than vegetation types dominated by shrubs, herbaceous plants, or grasses. Table 1 provides a summary of total acres burned by wildfires in 2020, along with fuel consumed and both carbon dioxide (CO2) and particulate matter (PM10 and PM2.5)3 emissions.

Table 1. Summary of 2020 Wildfire Area, Fuel Consumption, And Emissions

Wildfire Area Burned

(million acres)

Fuel Consumed (short tons)

CO2 (million metric tons)

PM10 (thousand short

tons)

PM2.5 (thousand short

tons)

4.2

81,097,083

106.7

1,394

1,181

Table 2 provides total acres burned and emissions for the top twenty largest wildfires, which comprised approximately 90 percent of total area burned and accounted for over 90 percent of total CO2, PM10, and PM2.5 emissions from all wildfires in 2020.

1 Method and Data Used in Wildfire Emission Estimation () 2 3 Inhalable Particulate Matter and Health (PM2.5 and PM10) | California Air Resources Board

1

Table 2. Top 20 Wildfires of 2020.

Fire Name August Complex

Wildfire Area Burned (acres)1

1,032,700

CO2 (million metric

tons)

27.7

PM10 (thousand short

tons)

368

PM2.5 (thousand short

tons)

312

SCU Complex

396,399

4.6

34

29

Creek

379,882

13.8

190

161

North Complex

318,777

10.9

132

112

Hennessey

305,352

3.5

27

23

Castle

170,648

6.4

84

71

Slater2

157,430

6.7

88

74

Red Salmon Complex

143,836

4.6

63

54

Dolan

124,527

2.1

27

23

Bobcat

115,998

2.5

24

21

CZU Complex

86,553

5.4

104

88

W-5 Cold Springs2

84,817

0.7

6

5

Caldwell

81,224

0.4

3

3

Glass

67,484

1.9

28

24

Zogg

56,338

0.7

6

5

Wallbridge

55,209

4.1

78

66

River

50,214

0.9

9

7

Loyalton

46,721

0.7

9

8

Dome

44,211

0.1

0.4

0.3

Apple

33,209

0.8

9

8

1 Emission estimates are associated with wildland vegetation and do not include developed areas, croplands, or water bodies.

2 Excludes emissions associated with areas beyond state boundary.

Figures 1 to 4 present annual wildfire acreages and emissions of CO2, PM10, and PM2.5 for 2000 to 2020.

2

Burn Area (Million Acres)

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

Figure 1. Acreage of Burned Wildland Vegetation Area*.

4.5 4.08

4

3.5

3

2.5

2

1.59

1.5

1.35

1.34

0.94

1.04

1

0.72

0.75

0.79

0.49 0.5 0.24 0.23

0.27 0.22

0.43

0.56 0.53 0.55

0.09 0.20

0.28

0

* These acreages do not include areas where wildland vegetation data for model inputs are not available, e.g., developed areas and croplands. Figure 2. Estimates of Wildfire CO2 Emissions.

120 106.7

100

80

60

41.7

39.1

40

31.3

20

18.3 13.5

19.9 12.6

5.4 6.2

5.2 2.0

8.8

11.3 14.7 17.2 19.2 10.5

1.3 3.1

4.8

0

CO2 Emissions (Million Metric Tons)

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

3

PM10 Emissions (thousand Short tons)

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

Figure 3. Estimates of Wildfire PM10 Emissions.

1,400

1,393

1,200

1,000

800

596 600

497

398 400

234 246

200

167 137

137 171

71 81

50 15

152 176 84

13 34

122

56

0

Figure 4. Estimates of Wildfire PM2.5 Emissions.

1,400

1,200

1,181

1,000

800

600

505

421

400

337

199 208

200

141 116

116 145

60 69

42 12

129 149 71

11 29

104

48

0

PM2.5 Emissions (thousand Short tons)

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020

4

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