Climate change adaptation cost in the US: what do we know?

Abstract

Researchers and policy makers increasingly recognize the need to adapt to future changes in climate, given that past emissions of greenhouse gases have already committed the world to some level of climate change. However, the current understanding of the costs and benefits of adaptation measures is still fairly rudimentary, and far from comprehensive. An assessment is presented of the current state of knowledge on the magnitude of adaptation costs in the United States. While incomplete, the studies suggest that adaptation cost could be as high as tens or hundreds of billions of dollars per year by the middle of this century. Key studies are identified in each sector, and the cost estimates and approaches to cost estimation are surveyed. Methodological issues are highlighted in interpreting, comparing, and aggregating adaptation cost estimates. Policy recommendations are made along with appropriate steps to make future adaptation cost studies more comparable within and across sectors and more accessible and relevant to policy and decision makers.

Policy relevance

Designing and implementing climate change adaptation policy requires good information about the effectiveness and cost of available adaptive options. The current state of knowledge on adaptation costs in the United States is assessed and significant gaps in the literature are highlighted – particularly in terms of sectoral and geographic coverage – as well as inconsistencies in methodologies and assumptions that hamper comparison across studies. Critical steps are identified that can be taken to make adaptation cost studies more accessible and useful to decision makers. The findings and recommendations are relevant to adaptation cost studies globally, not just in the United States.

Keywords:

• adaptation
• climate change
• cost estimates
• economic cost
• United States

Acknowledgements

Research assistance was provided by Rubab Banghu, Wendy Jaglom, Thuy Phung, and Cassandra Snow of ICF International. Editorial assistance was provided by Brad Hurley of ICF International. The authors also thank the following individuals for reviewing an early draft and providing constructive comments: Allison Crimmins, Reid Harvey, Mike Kolian, Jeremy Martinich, Sara Ohrel, Marcus Sarofim, Jim Titus, and Stephanie Waldhoff. We would also like to thank an anonymous reviewer and editor for their insights and suggestions. This work was supported by the U.S. Environmental Protection Agency's Office of Air and Radiation, under contract EP-W-07-068. The views expressed in this document are solely those of the authors and do not necessarily reflect those of the Agency.

Notes

1. Because there is only one, the regional study of recreation and tourism is discussed in Section 4, along with the state and local studies.

2. The methodology for projecting sea-level rise is an area of active research. Researchers currently project a relatively wide range for the expected rise in global sea level by the end of the century – between 18 cm and 201 cm compared with 1990 levels (NRC, 2010) – with IPCC (2007a) providing the lower end of the range. Estimates of sea-level rise used by studies in this section generally fall within this range.

3. Alaska is generally included as a separate region in US national climate assessments (see e.g. Karl et al., 2009).

4. In the US, expenditures on health care in 2010 were split roughly 45% and 55% between public and private entities, respectively. Of the public-sector portion of health care expenditures, the federal government shouldered 64% and state and local governments 36% (Martin, Lassman, Washington, & Catlin, 2012).

5. Climate sensitivity is the equilibrium global mean surface temperature change projected by a climate model run with a doubling of CO₂ concentration. Climate models with high equilibrium climate sensitivity project a warmer climate.

6. Precipitation is particularly difficult to model given its very localized behaviour.