Our impacts and adaptation assessment indicates that changing climate and changing
patterns of regional development have challenged North America and will continue
to do so. Damage costs from recent climatic events have increased, and conflicts
over climate-sensitive resources (e.g., fish) continue to occur. Future climatic
changes may exacerbate these problems and indeed create new ones. Opportunities
may arise from a warming climate, and some innovative adaptation mechanisms
(e.g., water banks) are being tested to address current problems. However, the
literature provides few cases on how adaptive strategies could be implemented
in the future as regional climates continue to change.
Recent studies in agriculture point to greater crop diversity and possibilities
for adaptation as factors in reducing estimates of future damage. Production
forestry is regarded in much the same way, except in high-latitude regions where
vulnerabilities to changing climate-related risks (pests, fire, permafrost thaw)
still are considered significant challenges for management. Estimates of future
damage to U.S. coastal zones have declined despite the recent series of high-cost
extreme events. However, studies also have documented changing vulnerabilities
of built (urban) environments to atmospheric events, risks to indigenous lifestyles,
and the challenge of managing resources within a changing climatic regime to
meet multiple objectives. Climate change along the U.S.-Mexican border
may result in social and economic problems related to transboundary water resources.
Unique natural ecosystems such as prairie wetlands, alpine tundra, and coldwater
ecosystems are at risk, and effective mitigation is unlikely.
As impact studies of North America attempt to include adaptation in a more
significant way, damage estimates in some sectors decline or become benefits.
Mendelsohn and Neumann (1999) illustrate this trend for agriculture, production
forestry, and coastal zone impacts in the United States. What also emerges,
however, is that high damage costs are still calculated for water-related activities
and summer energy demand. Most important, there are several outstanding methodological
issues related to the evolution of economic activities, adaptation assumptions,
and the value of nonmarket components, resulting in continued difficulties in
estimating the cost of impacts and the costs and benefits of adaptation responses.
If optimistic views about adaptation were realistic, North America should have
been better able to plan for extreme events. Recent experience demonstrates
high capability in emergency response, but long-term problems remain.
During recent extreme weather events, synergies between development pressures
and environmental changes have resulted in substantial damages. Examples documented
in Sections 15.2.1, 15.2.3, 15.2.7,
and 15.3.2 include water-quality problems resulting from
North Carolina hurricanes, damage from the 1998 ice storm, reductions in fish
stocks as a result of climatic shifts combined with fishing pressure, and various
impacts from recent water-level fluctuations in the Great Lakes. Unfortunately,
only a few climate change scenario studies explore these kinds of synergies.
Besides the challenge of projecting future economies, scenario studies of impacts
and adaptation also have to consider the varied demands of regional stakeholders
from the same resource and/or location. A summary of adaptation issues for North
American subregions is provided in Table 15-6.
A wide range of factorsincluding changing political and institutional
arrangements, technologies, and perceptionsmay influence regional development
futures. Concerns about development, equity, and sustainability are emerging
in international negotiations of the United Nations Framework Convention on
Climate Change and the Kyoto Protocol, and regional impacts/adaptation concerns
can play an important role in this debate (Munasinghe and Swart, 2000). How
could development paths alter a region's vulnerability to climate change? Could
incentives related to emission reduction also enhance adaptation? Or, could
management for certain environmental objectives lead to difficulties in meeting
others? The example from the Columbia basin (Section 15.3.2),
in which managing for fish protection could lead to increases in GHG emissions
(Cohen et al., 2000), illustrates the dilemma that many subregions could
face as they consider options for responding to climate change scenarios. How
can these interactions be addressed in scenario studies? How can the various
economic and social dimensions be accounted for so that there could be more
confidence in estimates of impacts damages and adaptation costs/benefits?
Additional information on alternative climate scenarios and regional development
futures will be needed in order to improve estimates of the costs of subregional
impacts of climate change and the costs and benefits of adaptation responses.
As measures associated with the Kyoto Protocol attract more attention from governments
and industries, consideration also should be directed at studies on the interplay
of mitigation and adaptation at the subregional scale.