Cloé Garnache

• Antonioni, Alberto; Ciccone, Alice; Garnache, Cloé; Ghivarello, Sara; Halse, Askill Harkjerr & Lipari, Francesca (2026). Public support for universal road pricing. Journal of Environmental Economics and Management. ISSN 0095-0696. 139(August 2026), p. 1–22. doi: 10.1016/j.jeem.2026.103377. Full text in Research Archive Show summary

  Distance-based road pricing can internalize driving externalities and provide fiscally sustainable infrastructure financing as vehicle electrification erodes fuel tax revenues. Yet, political resistance may pose a barrier to implementation. We provide the first comprehensive analysis of preferences for universal road pricing using a stated choice experiment with nearly 4000 Norwegian respondents. Policy alternatives vary systematically across urban peak prices, off-peak prices, non-urban prices, electric vehicle prices, and revenue allocation. We document robust majority support (70% to 80%) for most universal road pricing schemes, substantially exceeding typical support for local congestion charges. Support varies by design: public transport earmarking outperforms general budget allocation by eight percentage points, while moderate pricing dominates high pricing by six points. Support varies substantially with car use, urban versus rural residence, availability of transport alternatives, and institutional trust, but shows little sensitivity to income, toll exposure, or the likelihood of benefiting financially from road pricing. Latent class analysis identifies unconditional supporters (57%), systematic opponents (22%), and a persuadable middle (21%). Randomized information treatments generate modest effects, with factual information increasing support by 6 percentage points. Political barriers to road pricing may be lower than assumed with low to moderate pricing and credible infrastructure earmarking.

• Brodeur, Abel; Mikola, Derek; Cook, Nikolai; Fiala, Lenka; Brailey, Thomas & Briggs, Ryan [Show all 347 contributors for this article] (2026). Reproducibility and robustness of economics and political science research. Nature. ISSN 0028-0836. 652, p. 151–156. doi: 10.1038/s41586-026-10251-x. Full text in Research Archive Show summary

  Science aspires to be cumulative. Reproducibility efforts strengthen science by testing the reliability of published findings, promoting self-correction, and informing policy-making1. Computational reproductions, whereby independent researchers reproduce the results of published studies, are an essential diagnostic tool2–10. Such efforts should have greater visibility11–16. However, little social science reproduction and robustness has been conducted at scale10,13,17–23. Here we reproduced original analyses and conducted robustness checks of 110 articles that were published in leading economics and political science journals with mandatory data and code sharing policies17,18. We found that more than 85% of published claims were computationally reproducible. In robustness checks, our reanalyses showed that 72% of statistically significant estimates remain significant and in the same direction, and the median reproduced effect size is nearly the same as the originally published effect size (that is, 99% of the published effect size). Additionally, 6 independent research teams examined 12 pre-specified hypotheses about determinants of robustness. Research teams with more experience found lower levels of robustness, and robustness did not correlate with author characteristics or data availability. Robustness checks and reproduction of analyses with existing and updated data based on 110 articles in economics and political science journals with data and code-sharing requirements found high levels of robustness and reproducibility and determined that robustness was not dependent on author characteristics or data availability.

• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2024). Demand-Side Management in Fully Electrified Homes. Journal of the Association of Environmental and Resource Economists. ISSN 2333-5955. 12(2), p. 257–283. doi: 10.1086/731607. Full text in Research Archive
• Tanner, Sophia; Lupi, Frank & Garnache, Cloé (2022). Estimating visitor preferences for recreation sites in wildfire prone areas. International journal of wildland fire. ISSN 1049-8001. 31(9), p. 871–885. doi: 10.1071/WF21133. Full text in Research Archive Show summary

  Development into the wildland–urban interface, combined with heat and drought, contribute to increasing wildfires in the U.S. West and a range of damages including recreation site closures and longer-term effects on recreation areas. A choice experiment survey is used to estimate visitor preferences for vegetation and the effects of past fire at recreation sites. Intercept interviews are used to randomly select visitors at national forest sites near Los Angeles. The choice model results reveal that recreation sites with waterbodies and sites with tree cover, instead of shrubs or barren areas, are highly desirable, while evidence of past fires decreases the value of a site. We find the effects of past fire depend on vegetation type, fire intensity and time since the fire ended. Older forest fires and shrub fires are undesirable, but forest fires that reach the crowns of trees are least desirable. The findings add to evidence that fire damage to recreation areas extends beyond closures and depends on vegetation, which can inform the allocation of firefighting and prevention resources.

• Garnache, Cloé & Mérel, Pierre R. (2022). Environmental Policy in General Equilibrium: New Insights from a Canonical Model. Journal of the Association of Environmental and Resource Economists. ISSN 2333-5955. 9(1), p. 113–140. doi: 10.1086/716229. Full text in Research Archive Show summary

  This paper derives the incidence of a pollution tax in a stylized general equilibrium framework, building on previous work by Fullerton and Heutel. Using the CPI as numeraire, we show that tax incidence is a simpler problem than previously thought and that general insights can be derived without the need to restrict the parameter space. In addition, the counterintuitive possibility that an increase in the tax could increase the pollution level vanishes. The choice of the CPI as numeraire is further justified by the fact that environmental taxes, notably carbon taxes, are typically indexed on inflation.

• Reeling, Carson; Horan, Richard D. & Garnache, Cloé (2020). When the Levee Breaks: Can Multi‐Pollutant Markets Break the Dam on Point–Nonpoint Market Participation? American Journal of Agricultural Economics. ISSN 0002-9092. 102(2), p. 625–640. doi: 10.1002/ajae.12005. Full text in Research Archive
• Lupi, Frank; Basso, Bruno; Garnache, Cloé; Herriges, Joseph A.; Hyndman, David & Stevenson, R. Jan (2020). Linking Agricultural Nutrient Pollution to the Value of Freshwater Ecosystem Services. Land Economics. ISSN 0023-7639. 96(4), p. 493–509. doi: 10.3368/wple.96.4.493. Full text in Research Archive
• Srivastava, Lorie; Hand, Michael; Kim, John; Sánchez, José J.; Lupi, Frank & Garnache, Cloé [Show all 8 contributors for this article] (2020). How Will Climate Change Affect the Provision and Value of Water from Public Lands in Southern California Through the 21st Century? Agricultural and Resource Economics Review (ARER). ISSN 1068-2805. 49(1), p. 117–149. doi: 10.1017/age.2020.3. Full text in Research Archive Show summary

  We estimate the ecosystem service value of water supplied by the San Bernardino National Forest in Southern California under climate change projections through the 21st century. We couple water flow projections from a dynamic vegetation model with an economic demand model for residential water originating from the San Bernardino National Forest. Application of the method demonstrates how estimates of consumer welfare changes due to variation in water supply from public lands in Southern California can inform policy and land management decisions. Results suggest variations in welfare changes over time due to alterations in the projected water supply surpluses, shifting demand limited by water supply shortages or surpluses, and price increases. Results are sensitive to future climate projections—in some cases large decreases in welfare due to supply shortages—and to assumptions about the demand model.

• Garnache, Cloé; Reeling, Carson & Horan, Richard (2018). Efficiency gains from integrated multipollutant trading. Resource and Energy Economics. ISSN 0928-7655. 52(1), p. 124–136. doi: 10.1016/j.reseneeco.2018.01.005. Full text in Research Archive Show summary

  Interest in expanding market-based approaches involving intra-pollutant trading (trading “like” pollutants) to allow inter-pollutant trading (trading “dis-similar” pollutants) is growing. Because many pollutants are regulated separately, designing inter-pollutant markets requires considering pre-existing regulatory constraints. We examine the optimal choices of inter- and intra-pollutant trade ratios when (i) some firms generate multiple pollutants affecting different media and (ii) permit caps are sub-optimal, having been exogenously specified by prior regulations. While the first-best outcome is unobtainable in this setting, we find inter-pollutant trading enhances efficiency by offering an additional policy instrument: the inter-pollutant trade ratio. Moreover, adjustments to intra-pollutant trade ratios reflecting the joint production of dis-similar pollutants can enhance efficiency. We also find realistic cases where inter-pollutant trading may universally improve environmental quality, easing concerns that trading across environmental media may harm one medium. An example of nitrogen trading in Pennsylvania’s Susquehanna River Basin illustrates our results.

• Garnache, Cloé; Mérel, Pierre R.; Howitt, Richard & Lee, Juhwan (2017). Calibration of Shadow Values in Constrained Optimisation Models of Agricultural Supply. European Review of Agricultural Economics. ISSN 0165-1587. 44(3), p. 363–397. doi: 10.1093/erae/jbx005. Full text in Research Archive
• Klaiman, Kimberly; Oretga, David L. & Garnache, Cloé (2017). Perceived Barriers to Food Packaging Recycling: Evidence From a Choice Experiment of US Consumers. Food Control. ISSN 0956-7135. 73(B), p. 291–299. doi: 10.1016/j.foodcont.2016.08.017. Full text in Research Archive
• Garnache, Cloé; Mérel, Pierre R.; Lee, Juhwan & Six, Johan (2017). The Social Costs of Second-Best Policies: Evidence from Agricultural GHG Mitigation. Journal of Environmental Economics and Management. ISSN 0095-0696. 82, p. 39–73. doi: 10.1016/j.jeem.2016.10.004. Full text in Research Archive
• Garnache, Cloé & Mérel, Pierre R. (2017). The Social Costs of Environmental Goods Provision: A Cautionary Guide to the Revealed-Preference Approach. Journal of the Association of Environmental and Resource Economists. ISSN 2333-5955. 4(4), p. 1025–1052. doi: 10.1086/692915. Full text in Research Archive
• Garnache, Cloé; Swinton, Scott M.; Herriges, Joseph A.; Lupi, Frank & Stevenson, R. Jan (2016). Solving the Phosphorus Pollution Puzzle: Synthesis and Directions for Future Research. American Journal of Agricultural Economics. ISSN 0002-9092. 98, p. 1334–1359. doi: 10.1093/ajae/aaw027. Full text in Research Archive
• Klaiman, Kimberly; Oretga, David L. & Garnache, Cloé (2016). Consumer Preferences and Demand for Packaging Material and Recyclability. Resources, Conservation and Recycling. ISSN 0921-3449. 115, p. 1–8. doi: 10.1016/j.resconrec.2016.08.021. Full text in Research Archive
• Garnache, Cloé (2015). Fish, Farmers, and Floods: Coordinating Institutions to Optimize the Provision of Ecosystem Services. Journal of the Association of Environmental and Resource Economists. ISSN 2333-5955. 2(3), p. 367–399. doi: 10.1086/682167. Full text in Research Archive
• Garnache, Cloé & Mérel, Pierre R. (2015). What Can Acreage Allocations Say About Supply Elasticities? A Convex Programming Approach to Supply Response Disaggregation. Journal of Agricultural Economics (JAE). ISSN 0021-857X. 66(1), p. 236–256. doi: 10.1111/1477-9552.12074. Full text in Research Archive

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• Garnache, Cloé; Srivastava, Lorie; Sánchez, José J. & Lupi, Frank (2018). Recreation Ecosystem Services from Chaparral Dominated Landscapes: A Baseline Assessment from National Forests in Southern California. Springer. ISBN 9783319683027. 23 p. Full text in Research Archive

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• Halse, Askill Harkjerr; Ciccone, Alice; Garnache, Cloé; Lipari, Francesca; Ghivarello, Sara & Antonioni, Alberto (2025). Public Support for Universal Road Pricing. SSRN pre print. doi: 10.2139/ssrn.5984069. Full text in Research Archive Show summary

  Distance-based road pricing can internalize driving externalities and provide fiscally sustainable infrastructure financing as vehicle electrification erodes fuel tax revenues. Yet, political resistance may pose a barrier to implementation. We provide the first comprehensive analysis of preferences for universal road pricing using a stated choice experiment with nearly 4,000 Norwegian respondents. Policy alternatives vary systematically across urban peak prices, off-peak prices, nonurban prices, electric vehicle prices, and revenue allocation. We document robust majority support (70% to 80%) for most universal road pricing schemes, substantially exceeding typical support for local congestion charges. Support varies by design: public transport earmarking outperforms general budget allocation by 8 percentage points, while moderate pricing dominates high pricing by 5 to 7 points. Support varies substantially with car use, availability of transport alternatives, and institutional trust, but shows little sensitivity to income, urban residence, or toll exposure. Latent class analysis identifies unconditional supporters (57%), systematic opponents (22%), and a persuadable middle (21%). Randomized information treatments generate modest effects, with factual information increasing support by 6 percentage points. Political barriers to road pricing may be lower than assumed with moderate pricing and credible infrastructure earmarking.

• Eriksen, Andreas Eidspjeld & Garnache, Cloé (2025). Cloudy Judgments: The Timing of Weather-Induced Biases. Full text in Research Archive
• Garnache, Cloé; Ciccone, Alice & Andreassen, Gøril Louise (2025). Time- and Location-Specific Road Pricing: Effects on Travel Behavior and Public Support. doi: https:/ethz.ch/content/dam/ethz/special-interest/mtec/cepe/cepe-dam/documents/publications/policy-brief/Cloe_policy_brief_final.pdf. Full text in Research Archive Show summary

  • Urban congestion and environmental damage from car use impose substantial social costs. • First-best road pricing (distance-, time- and location-specific pricing) offers a promising approach to internalize these costs as technological development allows for precise monitoring. • A large-scale Randomized Controlled Trial (RCT) in Oslo tested road pricing with and without subsidies for active transport (walking and cycling). • Road pricing reduced external driving costs by 5.3%, mainly through a decrease in kilometers driven by non-electric vehicle (non-BEV) users. • Battery-electric vehicle (BEV) users showed minimal response to road pricing, suggesting that differentiated pricing based on vehicle type may weaken overall effectiveness. • A follow up experiment with an information treatment explaining the long-term benefits of road pricing on congestion and pollution increased public support by 4.4%, while experience with the road pricing scheme alone had little effect. • Combining road pricing with subsidies for cycling did not have large additional effects.

• Ciccone, Alice; Andreassen, Gøril Louise & Garnache, Cloé (2025). Presentasjon for Cicero: Road Pricing: Travel Behavior and Public Support. Full text in Research Archive
• Ciccone, Alice; Garnache, Cloé & Andreassen, Gøril Louise (2025). Road Pricing: Travel Behavior and Public Support. CESifo Working Papers. ISSN 1617-9595. doi: 10.2139/ssrn.5252587. Full text in Research Archive Show summary

  Using a large-scale randomized field experiment, we study behavioral responses to and public support for Pigouvian road pricing. Leveraging financial incentives, we find that drivers subject to distance-based charges reflecting external costs of driving—varying by location, time, and vehicle type—reduce their driving-related externalities by 5.3%, corresponding to a price elasticity between –0.07 and –0.15, with much weaker effects among users of battery-electric vehicles (BEVs). Furthermore, providing information on the expected benefits of road pricing enhances public support for such policies, whereas experience with road pricing has little impact.

• Garnache, Cloé (2025). Road Pricing: Travel Behavior and Public Support. Full text in Research Archive
• Garnache, Cloé (2024). Road Pricing: Travel Behavior and Public Support. Full text in Research Archive
• Garnache, Cloé (2024). A road pricing and subsidy field experiment: The role of policy packaging. Full text in Research Archive
• Halse, Askill Harkjerr; Ciccone, Alice & Garnache, Cloé (2024). Public support for universal road pricing: A stated choice experiment. Full text in Research Archive
• Garnache, Cloé (2023). Does the Salience of Climate-Related Risk Affect Asset Prices? Full text in Research Archive
• Jack, Lee & Garnache, Cloé (2023). Same forces driving insurers out of California have already taken toll on home prices. [Journal]. San Francisco Chronicle. Full text in Research Archive
• Garnache, Cloé (2023). Does the Salience of Climate-Related Risk Affect Asset Prices? Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2022). Hvilke husholdninger reagerer på høye strømpriser? Bevis fra et storstilt felteksperiment. Full text in Research Archive
• Isaksen, Elisabeth Thuestad; Garnache, Cloé & Nareklishvili, Maria (2022). From brown to green: Employment dynamics and skill demand in a low-carbon transition. Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2022). Norske husholdninger er svært sensitive for endringer i strømprisen. Full text in Research Archive
• Garnache, Cloé (2022). The Effect of Climate-Related Risks on the Residential Real Estate Market. Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2022). Stabilizing Electricity Demand with Peak Pricing: A Large-Scale Field Experiment. Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2021). Grid Transmission Critical Peak Pricing: A Large-Scale Field Experiment with Default Enrollment. Full text in Research Archive
• Garnache, Cloé (2021). Does the Salience of Risk Affect Large, Risky Asset Prices? Full text in Research Archive
• Hernæs, Øystein Marianssønn; Garnache, Cloé & Imenes, Anders Gravir (2021). Grid transmission critical peak pricing: A large-scale field experiment with default enrollment. Full text in Research Archive
• Garnache, Cloé (2020). Does the Salience of Risk Affect Large, Risky Asset Purchases? Full text in Research Archive
• Garnache, Cloé & Mérel, Pierre R. (2020). Environmental Policy in General Equilibrium: New Insights from a Canonical Model. Full text in Research Archive
• Garnache, Cloé (2020). Does the Salience of Risk Affect Large, Risky Asset Purchases? Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2020). Peak pricing in Norway: A large-scale field experiment. Full text in Research Archive
• Garnache, Cloé (2020). Does the Salience of Risk Affect Large, Risky Asset Purchases? Full text in Research Archive
• Garnache, Cloé; Hernæs, Øystein Marianssønn & Imenes, Anders Gravir (2020). Peak pricing in Norway: A large-scale field experiment. Full text in Research Archive
• Garnache, Cloé & Mérel, Pierre (2019). Taxation of non-market goods in general equilibrium. Full text in Research Archive
• Garnache, Cloé (2019). The Effect of Risk Salience on Asset Prices. Full text in Research Archive
• Garnache, Cloé & Guilfoos, Todd (2019). A City on Fire: Effect of Salience on Risk Perceptions. Full text in Research Archive
• Garnache, Cloé (2019). Does the Salience of Risk Affect Large, Risky Asset Purchases? Full text in Research Archive
• Garnache, Cloé (2019). Does the Salience of Risk Affect Large, Risky Asset Purchases? Full text in Research Archive
• Garnache, Cloé & Guilfoos, Todd (2019). The Effect of Risk Salience on Asset Prices. Full text in Research Archive
• Garnache, Cloé (2016). Book Review of "Handbook of Water Economics". Water Economics and Policy. ISSN 2382-624X. 2(2). doi: 10.1142/S2382624X16800035. Full text in Research Archive
• Ciccone, Alice; Halse, Askill Harkjerr; Andreassen, Gøril Louise; Garnache, Cloé & Wangsness, Paal Brevik (2026). Aksept for veiprising : Evidens fra en nasjonal spørreundersøkelse og et randomisert feltforsøk i Oslo-regionen. Transportøkonomisk institutt . ISSN 9788248018131. Full text in Research Archive Show summary

  Støtten til veiprising i befolkningen er høyere enn den politiske debatten ofte gir inntrykk av, men den er ikke uavhengig av hvordan ordningen er utformet. Støtten øker når prisene er lavere, inntektene brukes til transport¬formål, og innbyggerne får konkret informasjon om hvordan veiprising skiller seg fra dagens bompenger og drivstoffavgifter. Informasjon om kø og luftforurensning øker støtten i mindre grad og kun blant bilister. Inntekt og forventet privatøkonomisk gevinst eller tap har liten betydning. Erfaring med veiprising gjennom et forsøk ga bare begrensede endringer i holdninger, trolig fordi deltakerne opplevde kostnadene ved ordningen uten å oppleve de fulle gevinstene, som redusert kø.

• Garnache, Cloé; Isaksen, Elisabeth Thuestad & Nareklishvili, Maria (2025). Labor Market Impacts of the Green Transition: Evidence from a Contraction in the Oil Industry. CESifo network. doi: https:/www.ifo.de/DocDL/cesifo1_wp12057.pdf. Full text in Research Archive Show summary

  The transition to a low-carbon economy requires a contraction of fossil fuel sectors, raising questions about the labor market costs of reallocation. We study the 2014 oil price shock as a natural experiment to examine the contraction of Norway’s oil industry. Using matched employer–employee data, we estimate long-run effects on earnings and employment using two complementary approaches. A differencein-differences design shows moderate losses for all oil workers, while an event study reveals substantially larger and more persistent losses among displaced workers—up to 10% in earnings and 5% in employment nine years after displacement, especially for those with lower educational attainment. Although few displaced workers transition into green jobs, they are equally likely to enter green and brown (non-oil) sectors when accounting for the size of each destination sector. Earnings losses are larger for those entering green jobs rather than brown (non-oil) jobs, but smaller than for those entering other sectors. Decomposition results indicate that differences in establishment wage premiums—rather than skill mismatch—explain most of the observed gaps.

• Sommervoll, Dag Einar; Garnache, Cloé; Benedictow, Andreas & Barth, Nini (2025). On the supply side of the housing market. Norges miljø- og biovitenskapelige universitet (NMBU). ISSN 9788257522292. Full text in Research Archive Show summary

  Artiklene i denne avhandlingen omhandler boligmarkedet, med fokus på hvordan regulering på boligutvikling og markedsforhold påvirker boligtilbudet i storbyområder. Med høye og stigende boligpriser som en stadig mer presserende utfordring, har rollen til tilbudsbegrensninger fått økende oppmerksomhet. Å forstå forholdet mellom etterspørsel, tilbudsrespons og prisdynamikk er avgjørende for å adressere utfordringene i boligmarkedet. Den første artikkelen utforsker hvordan tilbudselastisiteter varierer under ulike reguleringsregimer og markedsforhold. Jeg kombinerer prisdata med igangsatte og ferdigstilte boliger, lokal sysselsetting og lokal byggeutvikling for de 25 største kommunene i Norge mellom 2003 og 2021 og estimerer tilbudselastisiteter. Resultatene viser en gjennomsnittlig tilbudselastisitet på 1,9 prosent, med Oslo som har en betydelig lavere elastisitet på 0,4 prosent. Leiligheter viser høyere elastisitet sammenlignet med eneboliger, tomannsboliger og rekkehus. Dette samsvarer med fortettingsstrategier i mange byer. Den andre artikkelen undersøker forholdet mellom boligpriser og gjenanskaffelseskostnader i seks norske byer. Vi estimerer også tomtepriser og fortjenestemarginer for å identifisere hvem som tjener på priser som overstiger minimumskostnadene for lønnsom produksjon. Den tredje artikkelen studerer virkningen av Leilighetsnormen som ble introdusert i 2008 i Oslo. Normen satte størrelsesbegrensninger på nybygde leiligheter, og vi estimerer effektene på priser i ulike størrelsessegmenter. Den siste artikkelen i avhandlingen beregner fundamentale boligprismodeller for 14 kommuner for å undersøke geografiske variasjoner i boligmarkedssykluser. Vi bruker også gapet mellom faktiske priser og fundamentale priser for å forutsi sannsynligheten for vendepunkter i boligprisutviklingen. Samlet bidrar artiklene til en bedre forståelse av drivere og begrensninger i boligtilbudet, og gir verdifull innsikt i mekanismene som påvirker boligmarkedets tilbud og utvikling.

• Hernæs, Øystein Marianssønn; Garnache, Cloé & Imenes, Anders Gravir (2022). Which Households Respond to Electricity Peak Pricing amid High Levels of Electrification? IZA discussion paper 15194; CESifo Working Paper No. 9657. Full text in Research Archive
• Garnache, Cloé & Mérel, Pierre R. (2020). Environmental Policy in General Equilibrium: New Insights from a Canonical Model. CESifo Working Paper Series 8354. Full text in Research Archive
• Garnache, Cloé (2020). Does the Salience of Risk Affect Large, Risky Asset Prices? SSRN. Full text in Research Archive
• Garnache, Cloé; Sandberg, Eli; Strømø, Ellen-Birgitte; Bjørkvoll, Thor; Bjelle, Eivind Lekve & Werner, Adrian [Show all 8 contributors for this article] (2020). Trondheim Spektrum under vann - Samfunnsøkonomiske konsekvenser av flom, stormflo og havstigning. Universitetet i Oslo. Full text in Research Archive Show summary

  Ved hjelp av aktsomhetskart og skadeberegninger analyseres flomrisiko som følge klimaendringer for Trondheim Spektrum i et hydrologisk og samfunnsøkonomisk perspektiv. Trondheim Spektrum er en arena for sport, næringsliv og kultur, plassert på Øya i Trondheim nær Nidelva. Spektrum sin plassering gjør den utsatt for flom, stormflo og havstigning. Flom og stormflo kan påføre Trondheim Spektrum, Trondheim kommune og Norge generelt store private og samfunnsøkonomiske kostnader. I fremtiden vil havstigning øke effekten av stormflo og flom i elveløpsmunningen. Covid-19-pandemien har hatt påvirkning på oppgavens analyse. Spektrum har måttet stenge og en planlagt befaring ble avlyst, flere møter og intervjuer har måttet bli gjennomført per telefon. Pandemien har gjort datainnhenting vanskelig. Hovedinnholdet i oppgaven starter i kapittel 6. Her beskrives metoden som er brukt i analysen. Kapittel 7 presenterer 50-, 100-, 200- og 500-årsflom, og 20-, 200- og 1000-års stormflo med 2017 og 2090 havnivå. Det er deretter gjort en konsekvensanalyse av scenariene som berører Trondheim Spektrum. Konsekvensanalysen er utføret ved bruk av aktsomhetskartene og erfaringstall fra andre rapporter og samtaler med bedrifter. Dette gir grunnlaget for beregning av skadekostnadene og den årlige risikokostnaden. Oppgavens sensitivitetsanalyse (kapittel 8) legger til grunn en høyere risiko for ekstremvær fremover enn de historiske tallene angir. Resultatene presentert som årlige risikokostnader viser økningen av årlig risikokostnad for de samme scenariene som analysert i kapittel 7. I kapittel 12 beskrives samfunnsøkonomiske konsekvenser ved å ikke klimatilpasse. Observasjoner viser at klimarelaterte hendelser øker i frekvens og intensitet. Dette øker risikoen for private og samfunnsøkonomiske tap. På lang sikt er det samfunnsøkonomisk lønnsomt å klimatilpasse kommunene. Historiske tall kan føre til underestimerte framskrivinger av fremtidig klimaendring. Det trengs mer nøyaktige fremskrivingsmodeller. Funnene viser at klimatilpasning burde skje etter lokale forhold, med mer ressursallokering til klimatilpasning fra kommuner og staten. Det er mer lønnsomt å være proaktiv enn reaktiv i klimatilpasningstiltak for å unngå store samfunnsøkonomiske tap i form av personskade, bygningsskade, nedsatt samfunnsfunksjon, nedsatt velferd og tapt tiltro til statens håndteringsevne av et klima i endring. Under en 1000-års stormflo med 2090 havnivå er skadekostnaden tilknyttet Spektrum beregnet til 8 543 381 kr og en årlig risikokostnad på 8 543 kr. Denne hendelsen ga størst total skadekostnad etterfulgt av 500-årsflom som viser 6 405 952 kr med 12 812 kr i årlige risikokostnader. I tillegg følger det kostnader tilknyttet produksjonstap, opprydning og avfukting. Med tanke på havstigning vil flom i elveløp nær munningen og stormflo forekomme oftere og med mer omfattende påvirkningskraft. Det er i slike områder også en liten sannsynlighet for at flom og stormflo forekommer samtidig.

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