Weather and climate phenomena have outsized impacts on society when they are particularly extreme. Extreme Event Attribution (EEA) seeks to quantify the extent to which extreme weather and climate phenomena are the result of anthropogenic climate change (ACC), and thus it has implications for many pertinent climate change discussions, including those on potential legal claims of loss and damages and calculations of the social cost of carbon. The Fraction of Attributable Risk (FAR) is one metric that is used to quantify the proportion of an extreme weather or climate “event” associated with ACC. The FAR is typically applied to changes in the likelihood of exceeding some geophysical value chosen, post hoc, to represent the “event” (e.g., i.e., rainfall amounts, flood depths, drought measures, temperature values, etc.). The FAR has further been used to estimate the fraction of observed impacts (e.g., lives lost or economic damage) that can be associated with ACC by multiplying realized impacts by the FAR (IFAR = Impact×FAR). Here, we illustrate with a few stylized examples that this IFAR calculation only produces reliably useful results when the weather or climate phenomena in question can be easily conceived of as a discrete binary “event” (i.e., the entirety of the event either occurs or it does not). We show that the IFAR calculation can produce misleading results when the weather or climate phenomena in question are on a continuum, and ACC can be thought of as altering the intensity of the geophysical value that is used in the eventhood definition. Specifically, we show that the IFAR calculation inflates the impacts associated with ACC in these circumstances because it inaccurately assumes that there would have been zero impact had the geophysical value chosen to define eventhood not been exceeded. We illustrate that for weather and climate phenomena on a continuum (e.g., floods, droughts, temperatures, etc.), a clearer way of conceptualizing the impacts associated with ACC is to compare the expected value of the impact between the ACC and preindustrial conditions across the full continuum.
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Allen M (2003) Liability for climate change. Nature 421:891–892
Brown PT (2016) Reporting on global warming: a study in headlines. Physics Today 69(10):10–11
Clarke BJ, FEL O, Jones RG (2021) Inventories of extreme weather events and impacts: implications for loss and damage from and adaptation to climate extremes. Clim Risk Manag 32:100285
Danabasoglu G, Lamarque JF, Bacmeister J, Bailey DA, DuVivier AK, Edwards J, Emmons LK, Fasullo J, Garcia R, Gettelman A, Hannay C, Holland MM, Large WG, Lauritzen PH, Lawrence DM, Lenaerts JTM, Lindsay K, Lipscomb WH, Mills MJ, Neale R (2020) The Community Earth System Model Version 2 (CESM2). J Adv Model Earth Syst 12
Easterling DR, Kunkel KE, Wehner MF, Sun L (2016) Detection and attribution of climate extremes in the observed record. Weather Clim Extremes 11:17–27
Frame D, Rosier S, Noy I, Harrington L (2020a) Cost of extreme weather due to climate change is severely underestimated. Carbon Brief. 6/12/2020. https://www.carbonbrief.org/guest-post-cost-ofextreme-weather-due-to-climate-change-is-severely-underestimated/. Accessed 7/1/2022
Frame DJ, Rosier SM, Noy I, Harrington LJ, Carey-Smith T, Sparrow SN, Stone DA, Dean SM (2020b) Climate change attribution and the economic costs of extreme weather events: a study on damages from extreme rainfall and drought. Climatic Change 162:781–797
Frame DJ, Wehner MF, Noy I, Rosier SM (2020c) The economic costs of Hurricane Harvey attributable to climate change. Climatic Change 160:271–281
Harrington LJ, Gibson PB, Dean SM, Mitchell D, Rosier SM, Frame DJ (2016) Investigating event-specific drought attribution using self-organizing maps. J Geophys Res Atmos 121(12):766–712,780
Hsiang SM (2016) Climate econometrics. National Bureau of Economic Research Working Paper Series No. 22181
Levin ML (1953) The occurrence of lung cancer in man. Acta Unio Int Contra Cancrum 9:531–541
Li S, Otto FEL (2022) The role of human-induced climate change in heavy rainfall events such as the one associated with Typhoon Hagibis. Climatic Change 172
Mitchell D, Heaviside C, Vardoulakis S, Huntingford C, Masato G, Guillod BP, Frumhoff P, Bowery A, Wallom D, Allen M (2016) Attributing human mortality during extreme heat waves to anthropogenic climate change. Environ Res Lett 11
Newman R, Noy I (2022) The global costs of extreme weather that are attributable to climate change. CESifo Working Paper No. 10053 Available at SSRN: https://ssrn.com/abstract=4266618
O'Neill B et al (2022) Key risks across sectors and regions. In: Climate change 2022: impacts, adaptation, and vulnerability. In: Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
Otto FEL (2017) Attribution of weather and climate events. Ann Rev Environ Resour 42:627–646
Otto FEL, Massey N, Van Oldenborgh GJ, Jones RG, Allen MR (2012) Reconciling two approaches to attribution of the 2010 Russian heat wave. Geophys Res Lett 39(4)
Perkins-Kirkpatrick SE, Stone DA, Mitchell DM, Rosier S, King AD, Lo YTE, Pastor-Paz J, Frame D, Wehner M (2022) On the attribution of the impacts of extreme weather events to anthropogenic climate change. Environ Res Lett 17:024009
Philip S, Kew S, Van Oldenborgh GJ, Otto F, Vautard R, Van Der Wiel K, King A, Lott F, Arrighi J, Singh R, Van Aalst M (2020) A protocol for probabilistic extreme event attribution analyses. Adv Statistic Climatol, Meteorol Oceanograph 6:177–203
Ricke KL, Moreno-Cruz JB, Schewe J, Levermann A, Caldeira K (2016) Policy thresholds in mitigation. Nature Geosci 9:5–6
Seneviratne SI, Zhang X, Adnan M, Badi W, Dereczynski C, Di Luca A, Ghosh S, Iskandar I, Kossin J, Lewis S, Otto F, Pinto I, Satoh M, Vicente-Serrano SM, Wehner M, Zhou B (2021) Weather and climate extreme events in a changing climate. In: Climate change 2021: the physical science basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
Stott PA, Christidis N, Otto FEL, Sun Y, Vanderlinden J-P, van Oldenborgh GJ, Vautard R, von Storch H, Walton P, Yiou P, Zwiers FW (2016) Attribution of extreme weather and climate-related events. Wiley Interdiscip Rev Clim Chang 7(1):23–41
Stott PA, Stone DA, Allen MR (2004) Human contribution to the European heatwave of 2003. Nature 432:610–614
Wehner M, Sampson C (2021) Attributable human-induced changes in the magnitude of flooding in the Houston, Texas region during Hurricane Harvey. Climatic Change 166
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Brown, P.T. When the fraction of attributable risk does not inform the impact associated with anthropogenic climate change. Climatic Change 176, 115 (2023). https://doi.org/10.1007/s10584-023-03591-4