Infrastructure provides a broad range of human, environmental, and economic services including buildings, transportation, waste removal and treatment, water lines, communications, and electric power grids designed to improve and sustain our society and our quality of life (Kirshen et al., 2008b). The importance of infrastructure to an industrialized economy is reflected in the magnitude of its investments: in 2007, for example, the U.S. Bureau of Economic Analysis valued the stock of all public non-defense fixed assets in the United States at approximately $8.2 trillion (Heintz et al., 2009).

Changing risk of heat waves and droughts, storms and floods, and rising sea levels are just a few of the hazards climate change poses to infrastructure (Kraas, 2008). These extreme events confront human systems and constructs with weather conditions far outside their accustomed range (Wilbanks et al., 2007). The exposure of society and infrastructure to climate change is exacerbated by the fact that much of the world’s population growth over the next few decades is likely to occur in urban areas, as they double in size from 3 to more than 6 billion from 2007 to 2050 (UN, 2008). At the same time, however, this sector has a greater ability to adapt to changing conditions than many others, as humans created the systems being affected by climate change.

In the past, other human stressors on infrastructure—from rapidly expanding urban populations to deteriorating and aging systems, many of them operating on time scales of years rather than decades—meant that climate change was rarely considered as a key influence on infrastructure costs. However, climate changes in recent decades have increased awareness regarding the risk of significant and costly impacts to infrastructure: whether from melting permafrost in the Arctic affecting roads, pipelines, and buildings, or from storm surges in the Gulf potentially flooding and damaging homes, cities, highways, and rail lines (USGCRP, 2009; Figure 5.9).

Infrastructure response to climate change is not always continuous but can be step-wise as system failure may occur above a certain threshold: whether an underpass tends to flood when more than 2.5 inches of rain falls in a 24-hour period, for example, or train rails warp only when temperatures rise above a given threshold. Local conditions can further magnify the susceptibility of cities to climate-related impacts (Wilbanks et al., 2007). High-latitude and coastal areas are uniquely vulnerable to climate change.