A Decade of California Wildfire
Total acres burned over 10 years: 13.1 million. The variation is extreme — 2020 burned 4.3 million acres while 2023 burned just 57,000. A fire season is not a predictable event; it is a draw from a fat-tailed distribution.
| Year | Acres | Fires | Severity |
|---|---|---|---|
| 2020 | 4,257,863 | 9,917 | Unprecedented |
| 2021 | 2,569,009 | 8,835 | Catastrophic |
| 2018 | 1,893,913 | 7,948 | Catastrophic |
| 2017 | 1,548,429 | 7,117 | Catastrophic |
| 2015 | 893,362 | 6,186 | Severe |
| 2016 | 669,534 | 6,959 | Moderate |
| 2014 | 625,540 | 5,620 | Moderate |
| 2022 | 362,455 | 7,667 | Moderate |
| 2019 | 253,321 | 7,860 | Mild |
| 2023 | 56,601 | 5,606 | Mild |
Trend: +43,323 acres/year over the decade. Worst-to-best ratio: 75:1. Mean: 1.31M acres/yr.
Who Gets Smoked the Most?
| Region | Avg Smoke Days/yr | Peak Year | Peak Days | Mean PM2.5 (smoke) | Trend (days/decade) |
|---|---|---|---|---|---|
| San Joaquin Valley | 22 | 2020 | 55 | 48.5 µg/m³ | +5.8 |
| Sacramento | 18 | 2021 | 45 | 47.8 µg/m³ | +5.1 |
| LA Basin | 15 | 2020 | 42 | 47.7 µg/m³ | +4.2 |
| Bay Area | 12 | 2020 | 38 | 48.4 µg/m³ | +3.5 |
| Rest of CA | 10 | 2020 | 30 | 47.2 µg/m³ | +2.8 |
San Joaquin Valley is the most vulnerable region: 22 smoke days per year on average, reaching 55 days in 2020. It also hosts 35% of California’s solar capacity (14 GW), making it the nexus of smoke exposure and solar vulnerability. The trend of +5.8 days per decade means SJV could see 32 smoke days by 2035.
From Mild to Catastrophic
The ratio between extreme and mild is 11.5:1 for solar losses. An extreme year generates 99 short tons of NOx from peaker dispatch alone. The solar penalty scales nonlinearly with fire severity because extreme events affect a larger fraction of the state simultaneously.
Smoke Is Getting Worse
Every region shows a positive trend in smoke days per decade. Combined with the solar buildout in the CEC’s SB 100 implementation pathway (~40 GW → ~100 GW by 2045 — SB 100 is technology-neutral; the solar trajectory is the CEC’s lowest-cost pathway assumption, not statutory language), the future annual solar loss is compounding:
| Year | Projected Smoke Days | Solar (GW) | Lost (GWh/yr) | Lost Revenue |
|---|---|---|---|---|
| 2025 | 18 | 40 | 148 | $7M |
| 2030 | 20 | 55 | 227 | $11M |
| 2035 | 23 | 70 | 319 | $16M |
| 2045 | 27 | 100 | 543 | $27M |
By 2045, the combination of more smoke days and more solar capacity means annual smoke losses reach $27M/yr — 4.5 times today’s level. This is still dwarfed by the health cost trajectory, but it is a grid reliability problem during fire season.
Fidelity: L1 literature synthesis. The inputs are published Cal Fire statistics and peer-reviewed smoke climatology (Liu et al. 2016, Aguilera et al. 2021, Jaffe et al. 2020). The smoke penalty sits at $6M–$22M/yr against a $0.229B transport-policy EVPI ceiling — two orders of magnitude below the decision it feeds, so L1 resolves it. An L2 satellite upgrade (MODIS MAIAC AOD, 50–100 GB) only pays off if solar-penalty stakes cross into billions, and Inv 14 shows they do not.
Cal Fire 2014–2023 · Liu et al. 2016 (smoke day trends) · Aguilera et al. 2021 (CA smoke exposure) · Jaffe et al. 2020 (smoke climatology) · Gao et al. 2021 (GHI-PM2.5) · Peters et al. 2018 (solar soiling) · CEC 2024 SB 100 projections