Overall, strengthening infrastructure assets seem a very robust solutions that is very likely to be cost‐ effective, has a high likelihood to generate very large benefits, and cannot generate massive losses, even in the worst‐case scenarios.

The urgency of designing better infrastructure is also evident in the simulations (Figure 4). The cost of delaying action to 2030 is positive in 93 percent of the scenarios. The only scenarios in which delaying action is preferable are scenarios in which strengthening infrastructure assets has a benefit‐cost ratio below or very close to one. This happens when the cost of strengthening is very high (close to 5 percent), asset losses due to disaster are small, few infrastructure disruptions are explained by natural hazards, and climate change does not increase the frequency and magnitude of hazard impacts on infrastructure assets. The median cost of delaying action to 2030 is $1 trillion.

# Conclusion

While it appears out of reach to estimate the precise benefit‐cost ratio of strengthening infrastructure assets, it is possible to show that (1) this is a very robust option, which is very unlikely not to reveal cost‐ effective, and (2) acting earlier if preferable to delaying action. Moreover, the desirability of investing in the options to make infrastructure assets more resilient is underestimated in this analysis, since only the disruptions due to natural hazards are considered. In practice, more robust assets are also likely to resist better to other failures (including voluntary ones), leading to larger benefits than those estimated here.

# References

Braese, Johannes, Jun Rentschler, and Stéphane Hallegatte. 2019. “Resilient Infrastructure for Thriving Firms: A Review of the Evidence.” _World Bank Policy Research Working Paper_ .

- Field, Christopher B., and Vicente R. Barros. 2014. “Climate Change 2014 Impacts, Adaptation, and Vulnerability | Part A: Global and Sectoral Aspects.” Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma,. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. http://www.ipcc.ch/pdf/assessment‐report/ar5/wg2/WGIIAR5‐PartA_FINAL.pdf.

- Koks, E.E., J. Rozenberg, C. Zorn, M. Tariverdi, M. Vousdoukas, S.A. Fraser, J.W. Hall, and S Hallegatte. 2019. “A Global Multi‐Hazard Risk Analysis of Road and Railway Infrastructure Assets.”

- Lempert, Robert J., David G. Groves, Steven W. Popper, and Steve C. Bankes. 2006. “A General, Analytic Method for Generating Robust Strategies and Narrative Scenarios.” _Management Science_ 52 (4): 514–28. https://doi.org/10.1287/mnsc.1050.0472.

- Miyamoto. 2019. “Overview of Engineering Options for Increasing Infrastructure Resilience.” Washington DC: World Bank.

Nicolas, Claire. 2019. “Energy Paper.” Background Paper prepared for this report.

Obolensky, Marguerite, Alvina Erman, Julie Rozenberg, Paolo Avner, Jun Rentschler, and Stéphane Hallegatte. 2019. “Infrastructure Disruptions: Impacts on Households.” _World Bank Policy Research Working Paper_ .

- Rentschler, J, M Kornejew, S Hallegatte, M Obolensky, and J Braese. 2019. “Underutilized Potential: The Business Costs of Unreliable Infrastructure in Developing Countries.” World Bank Policy Research

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