Editing IPCC:AR6/SROCC/Chapter-4 (section)

===== 4.4.2.5.7 Economic-efficiency of accommodation =====

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There is ''high confidence'' that many accommodation measures are very cost-efficient. Flood EWS coupled with precautionary measures have been shown to produce significant economic benefits (Parker, 2017). Elevating areas at high risk and retrofitting buildings in Ho Chi Minh City, for example, have benefit-cost ratios of 15 under SLR of 180 cm and a discount rate of 5% during the 21st century (Scussolini et al., 2017). In the context of the National Flood Insurance Program in the USA, it has been estimated that elevating new houses by 60 cm might raise mortgage payments by 240 USD yr <sup>-1</sup> , but reduce flood insurance by 1000–2000 USD yr <sup>-1</sup> depending on the flood zone (FEMA, 2018), although this only addresses present extremes and ignores future SLR (Zhu et al., 2010). In Europe, the benefits of installing a cross-border continental-scale flood EWS are estimated at 400 EUR per EUR invested (Pappenberger et al., 2015).

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