Subregions within North America can be affected by global climate change through direct first-order effects on land and water resources and through indirect impacts that are related to reactive and proactive responses by actors within and outside the subregion. Direct effects include incremental processes and extreme weather events with long-term impact on the region's environmental, social, or economic systems. Indirect effects would include societal changes that could be set in motion, primarily by policies generated outside the region, to mitigate greenhouse warming or adapt to perceived threats.

Calculations of climate-related impacts within subregions must consider both direct and indirect effects. Actual impacts will depend on the effectiveness of adaptation. For example, changes in growing season, natural streamflow, or climate-related demand for heating and cooling energy can be calculated directly from changes in climatic parameters. However, changes in potential may not necessarily lead to a response by stakeholders. Other factors may intervene to prevent a subregion from adapting to a new climate-related opportunity or risk, including changes in market conditions, institutional arrangements, and management objectives.

Because North America includes areas of intensive urban and landscape management, as well as areas of "extensive" management, adaptation capabilities and vulnerabilities are likely to vary between subregions. There is potential for maladaptation, in part as a result of the availability of insurance and disaster relief measures (MacIver, 1998). Vulnerabilities also exist in highly developed regions with well-maintained infrastructure (e.g., dams designed for flood control) because of the growing need to manage resources to achieve multiple objectives. Would climate change ameliorate or exacerbate these risks? Analysis of case studies can provide guidance.

Table 15-5: Estimated damages from 1998 ice storm.a
Type of Loss	Canada (CDN$)	United States (US$)	Total (US$)
Insured losses	$1.44 billion	$0.2 billion	$1.2 billion
Insurance claims	696,590	139,650	835,240
Deaths	28	17	45
People (customers) without power	4,700,000 (1,673,000)	546,000	5,246,000
Electricity transmission towers/distribution poles toppled	130/30,000	unknown	unknown
Electric transmission system damage	$1 billion	unknown	unknown
Manufacturing, transportation, communications, and retail business losses	$1.6 billion	unknown	unknown
Forests damaged	unknown	17.5 million acres	unknown
Loss of worker income	$1 billion	unknown	unknown
Dairy producers experiencing business disruption	5,500	unknown	unknown
Loss of milk	$7.3 million	$12.7 million	$18 million
Agricultural sector (poultry, livestock, maple syrup)	$25 million	$10.5 million	$28 million
Quebec and Ontario governments	$1.1 billion
a Based on analysis conducted by the Canadian Institute for Catastrophic Loss Reduction and U.S.-based Institute for Business and Home Safety, both of which are insurance industry organizations (Lecomte et al., 1998). Losses as of 1 October 1998 (1 CDN$ = 0.7 US$).

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