Background - Climate Change and Infrastructure, Urban Systems, and Vulnerabilities - page 4

varied considerably in their treatment of such issues as scenarios and confidence characteri-
zation. In most cases, in fact, the sources do not refer to climate change scenarios at
all. Second, the nature of much of the source material, often qualitative and issue-
oriented, severely limited any atempt to estimate quantitative bounds on probabilities.
And third, the highly compressed time schedule for the technical report preparation
process limited potentials for engagement and communication and made it difficult to
impose top-down strictures on report authors.
Given a body of source material that is a highly imperfect fit with the NCA guid-
ance, the report has made an effort to frame its assessment findings in broad contexts
of risk-based framing, scenarios, and confidence characterization. Assessment findings
are associated with evaluations of the degree of scientific consensus and the strength of
the available evidence. Where appropriate, findings are also associated with two general
scenario-related framings of possible future climate changes: (1) “substantial ”, which is
approximated by IPCC Special Report on Emission Scenarios (SRES) emission scenario
A2, and (2) “ moderate” , which is approximated by scenario B1.
4) ASSESSMENT FINDINGS
Assessment findings are provided at the end of each major section of the report, in-
cluding sections on risk management strategies; knowledge, uncertainties, and research
gaps; and developing a sustained capacity for continuing assessments. The complete list
of twenty assessment findings is included in the report's Executive Summary.
B. The Scope Of The Report
1) HOW “INFRASTRUCTURES” ARE DEFINED
For this study, the emphasis is on built infrastructures (as contrasted, for instance,
with social infrastructures). Such infrastructures include urban buildings and spaces,
energy systems, transportation systems, water systems, wastewater and drainage sys-
tems, communication systems, health-care systems, industrial structures, and other prod-
ucts of human design and construction that are intended to deliver services in support of
human quality of life.
Experience over the past decade has shown vividly how vulnerable such infrastruc-
tures can be to the types of extreme weather events that are projected to be more intense
and/or more frequent with future climate change. For instance, the Gulf Coast contin-
ues to be highly vulnerable to the effects of climate change despite rebuilding and new
design features for infrastructure. While additional protection has been provided in the
form of new levees and other structures; higher, stronger and beter engineered roads
and bridges; and more complete monitoring and communications equipment; the mag-
nitude of the potential impacts of sea-level rise, storm effects and heat -- in conjunction
with ongoing changes in the natural environment -- will continue to require atention
and investment for a considerable time to come.
In 2008, the U.S. Global Change Research Program issued a “Gulf Coast Study” (SAP
4.7, 2008) that detailed the impacts of climate change on the central Gulf Coast from
Houston to Mobile, AL. The study concluded that two- to four-feet of relative sea level
rise were likely to occur in the region by 2050, including the continuing subsidence of