disruptions than those of 1859. Basic to his contention are the enormous changes to the nation’s infrastructure over the past century and a half and the virtual certainty of additional changes in the future.

Today scientists have a better understanding of the technical causes and implications of space weather, and even of appropriate technical responses to it, than they did in the past. Knowledge of the social, institutional, and policy implications of space weather is growing but is still rudimentary. The disruption of the telegraph system in 1859 caused problems in communication, but because modern society is so dependent on large, complex, and interconnected technical systems—and because these systems not only are vital for the functioning of the economy but also are vulnerable to electromagnetic events–a contemporary repetition of the Carrington event would cause significantly more extensive (and possibly catastrophic) social and economic disruptions. La Porte said that understanding the consequences resulting from interdependencies of infrastructure disrupted during significant space weather is essential. Caverly stated that although systems may be well designed themselves, there is a need to consider the “system of systems” concept and to examine the associated dependencies in detail. He added that today there is growing awareness among planners, managers, and designers of this necessity.

In a parallel example, Caverly compared the effects of the 1906 San Francisco earthquake to its potential effects today. To better understand this analysis, consider three terms of art: direct impact of an event on an infrastructure, dependency of one infrastructure on another, and the interdependency of an infrastructure on the one it impacts. The 1906 earthquake had enormous direct influence on virtually all the infrastructures of San Francisco. Today such an earthquake would have direct local consequences but the disruptions would also be felt across the country because of the interconnectedness of the national infrastructures (Figure 3.1).

Caverly discussed how a space weather event could have an impact on delivery of electric power. For example, following a power outage, electrified transportation ceases for the duration of the outage. When there is a short-term power outage with rapid restoration, the impacts may be minimal. However, with a long-term outage (say,

FIGURE 3.1 Connections and interdependencies across the economy. Schematic showing the interconnected infrastructures and their qualitative dependencies and interdependencies. SOURCE: Department of Homeland Security, National Infrastructure Protection Plan, available at http://www.dhs.gov/xprevprot/programs/editorial_0827.shtm.

FIGURE 3.1 Connections and interdependencies across the economy. Schematic showing the interconnected infrastructures and their qualitative dependencies and interdependencies. SOURCE: Department of Homeland Security, National Infrastructure Protection Plan, available at http://www.dhs.gov/xprevprot/programs/editorial_0827.shtm.



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