Fig. 4.

Monetized economic and health impacts of drought-induced fossil fuel generation. (A) Monetized damages from extra CO₂ emissions, CH₄ leakage, and PM_2.5-related mortalities, due to runoff changes (relative to the 1980 to 2021 average). Monetized values are calculated using a social cost of carbon value of $117 per ton, a social cost of methane value of $1,257 per ton (year 2020 dollars) from US EPA (34), and a value of statistical life of $10.95 million per mortality (year 2019 dollars). (B) Declines in annual monetized damages over time are a result of declining emissions factors (i.e., emissions per unit energy production) over the western United States (2021 values are normalized to 1). (C) Total damages of the 2012 to 2016 drought in California, compared to estimates of the direct economic impacts from the prior literature due to reductions in hydropower and the increased electricity demand (27, 28). CO₂ damages are calculated using two SCC values, $117 per ton as in A and $193 per ton (under a 2% discount rate following ref. 43). In C, we only calculate the impacts originating from fossil fuel plants in CA and impacts in other regions due to the runoff changes in CA.