Framing Climate Change Implications for Infrastructures and Urban Systems - Climate Change and Infrastructure, Urban Systems, and Vulnerabilities - page 21

interdependencies of infrastructure systems, the reduction of output in one industry or
the loss of one infrastructure can cause the reduction in the output in other industries or
other infrastructures. We also observe cascading reductions in output across industries
when key industries, such as transportation (e.g., ports), chemical (e.g., chlorine) and en-
ergy (electricity) sectors, suffer reduced output for an extended period. Figure 3 (above)
shows some of the loops of interdependence across several infrastructures. The direct
climatic impacts may include damage to productive capacity, whose stopgap repair can
increase the future sensitivity to evolving climate change, or where resiliency-improving
investments can insulate productive resources from future disruptions. The indirect im-
pacts can be process changes in other industries or the diversification of supply chains.
Interdependencies can be interregional, for example, flooding in Thailand or cyclones
in South Korea directly affect critical U.S. supply chains, e.g., computer hard drive man-
ufacturing and precision component parts (note also implications of the Fukushima nu-
clear power plant disaster). As a consequence, the ensuing effects of infrastructure response to
climate change can produce path-dependent influences on future economic conditions.
Concomitant changes in production processes can change costs and the competiveness
of local industries, leading to abandonment of facilities or the migration of the activi-
ties to other geographical areas. Some industries are more vulnerable to climate change
events than others. Floods and snowstorms can quickly affect transportation systems,
while droughts can have sizable impacts on agricultural and electrical generation sys-
tems. Assessments that neglect infrastructure vulnerability, interdependencies, and re-
silience miss fundamental elements of economic and societal risk.
Integrated assessment models (IAMs) are used extensively to evaluate climate change
scenarios. IAMs currently focus on greenhouse gas (GHG) emissions and their mitiga-
tion in the context of economic growth. Adding infrastructure simulation capabilities
would allow an assessment of adaptation as well as the quantifying risk to economies
and societies. As such, infrastructure modeling is appropriately integrated assessment
modeling because of the interaction between infrastructure adequacy and economic
growth over time. In general, the current infrastructure models operate at different
scales and have different computational requirements from most IAMs. For compati-
bility with IAMs, the analyses of infrastructure risks would need to be represented at
regional levels with global coverage. Ultimately, there will be need for a hierarchical
analytical capability that can describe the propagation of local effects to national and
international implications - and the converse.
B. Infrastructure System Services
Although considerations of infrastructure often seem totally concentrated on physical
structures, those structures are especially important because they are means to social
ends. In other words, services and not structures are what are important to users and
decision-makers.
When critical infrastructure and thus critical services are disrupted by climate effects
in a metropolitan seting, cascading impacts can occur afecting part or all of the area,
social and economic activity and the health and quality of life of the people themselves.
These impacts can be viewed as three tiers of effects: 1) direct impacts on citizens and