8.4.5. Systemic Nature of the Problem
In evaluating the implications of climate change impacts on North America,
one must consider that although there are regional differences in response by
sector and by subregion, the scale of anticipated changes is such that there
may be adjustments taking place in every sector and subregion simultaneously.
Any one of the impacts (whether beneficial or detrimental) that has been discussed
for North America may appear well within the capability of existing structures
and policies to adapt. However, the fact that they are occurring simultaneously
may pose a significant challenge to resource managers and policymakers. The
systemic nature of impacts and issues raises important questions about society's
ability to manage the aggregate/cumulative risks posed by climate change.
This systemic problem also must be placed into the larger context of the multiple
stressors that are and will be acting on North American resources. Many stressors
(environmental, social, and economic) influence natural and human systems and
pose significant challenges for decisionmakers and policymakers. The challenge
of coping with the cumulative risks of climate change adds to the complexity.
What must be kept in mind is that changing climate is not the only-nor necessarily
the most important-factor that will influence these systems and that it cannot
be isolated from the combination of other factors determining their future welfare.
8.4.6. Integrated Nature of the Problem
A complete assessment of the effects of climate change on North America must
include a consideration of the potential interactions and feedbacks between
sectors and subregions. Changes in the climate system can affect natural and
human systems in a chain of consequences (see Figure 8-12).
Some of these consequences are the results of direct effects of climate change
and variability on physical, biological, and socioeconomic systems; some result
from indirect links between climate-sensitive systems and related social and
economic activities; some result from feedbacks between human activities that
affect the climate system, which in turn can lead to further impacts (e.g.,
human activities affecting the climate system-which, in turn, can lead to further
impacts on human health, the environment, and socioeconomic systems).
|Figure 8-12: Chain of consequences.
Most existing studies of potential impacts have focused on the more narrow
direct pathway between climate change and climate-sensitive systems and sectors.
These effects include direct climate impacts on human health (e.g., heat stress),
environmental processes (e.g., impacts of runoff and streamflow on the hydrological
cycle, coastal damages caused by sea-level rise, changes in biodiversity), market
activities that are linked to the environment (e.g., agriculture, commercial
timber, waterborne transport), and human behavior (e.g., changes in air conditioning
use as a result of changes in the frequency of very hot days).
Fewer studies have captured the more indirect effects of climate change, which
may take many different forms. Many of the primary determinants of human health
(adequate food, clean water, secure shelter) are related to outputs from sectors
such as agriculture, water resources, and fisheries. The potential spread of
infectious diseases is indirectly related to climate change through changes
in ecosystems and the hydrological cycle. Therefore, it is important to integrate
these relevant systems into a human health assessment.
Other indirect effects include secondary impacts on market activities that
are dependent upon sectors directly affected by climate change. For example,
climate change will directly affect crop yields and hence agricultural production
and prices. These effects, in turn, will influence the prices of goods and services
that use agricultural commodities in their production, which will feed back
to the agricultural sector and agricultural prices. Shifts in agricultural production
could have a large impact on freight transport patterns and may require adjustments
in the transportation network-with marine, road, rail, and air links potentially
needing expansion into areas not currently serviced. One study of the U.S. economy
suggests that the direct effects of climate change on U.S. agriculture, energy
use, and coastal protection activities could lead to price increases for all
economic sectors, causing a reallocation of spending and the sectoral composition
Other indirect effects include changes in nonmarket activities as a result
of projected impacts of climate change on ecosystems (e.g., changes in recreational
fishing as a result of projected impacts of climate change on aquatic ecosystems).
For example, the loss of fishing opportunities could be severe in some parts
of the region, especially at the southern boundaries of fish species' habitat
regions. The loss of fishing opportunities may result in economic losses for
the fishing industry. In turn, related industries such as the food, transportation,
and lodging industries will be affected. All of these examples illustrate how
each sector that is directly or indirectly affected by climate change can adversely
As this chain of consequences illustrates, the task of assessing various impacts
and the feedbacks among them is enormously complex and requires a number of
simplifying assumptions. Although there are complex macroeconomic models to
assess the costs and consequences of various mitigation policies, the state
of the art in impact work at present limits the insights that can be gained
from this kind of "top-down" modeling. The dominant approach has been "bottom-up"-aggregating
direct and indirect impacts into a single overall estimate, without much attention
to feedbacks among various sectors. Nevertheless, the complex, integrated nature
of the climate change problem suggests the need for integrated assessments that
incorporate many aspects of the region. Sectoral assessments alone would not
Examples of broad, integrated approaches to climate impact assessment are two
regional studies in North America: the Mackenzie Basin Impact Study and the
Great Lakes-St. Lawrence Basin Project.
Box 8-3. Mackenzie Basin Impact
The Mackenzie Basin Impact Study (MBIS) was a 6-year climate change impact
assessment focusing on northWestern Canada (supported by Environment Canada
and other sponsors) to assess the potential impacts of climate change
scenarios on the Mackenzie Basin region, its lands, its waters, and the
communities that depend on them (Cohen, 1997a). The MBIS was designed
to be a scientist-stakeholder collaborative effort, with 30 research activities
on various topics-ranging from permafrost and water levels to forest economics
and community response to floods.
The MBIS integration framework included several integration modeling
exercises-such as resource accounting, multiregional input-output modeling
and community surveys of the nonwage economy of an aboriginal community,
a multiobjective model focusing on scenarios of changing land utilization,
and a land assessment framework (ILAF) with goal programming and an analytic
hierarchy process. MBIS researchers identified six main policy issues
related to climate change as another form of "vertical integration": interjurisdictional
water management, sustainability of native lifestyles, economic development
opportunities, buildings, transportation and infrastructure, and sustainability
of ecosystems (Cohen, 1997a). Integration also was attempted through information
exchange (scenarios and data) while study components were in progress
and a series of workshops that provided opportunities for scientists and
stakeholders to express their views on how climate change might affect
the region and to react to research results (Cohen, 1997a,b).
Integration research framework for the Mackenzie
Basin Impact Study (Cohen, 1997a).
The main result of the integrated assessment was that most participating
stakeholders saw climate impacts scenarios as a new and different vision
of the future for their region, and that adaptation measures alone might
not be enough to protect the region from adverse impacts.
These two efforts have tried to account for some of the synergies and interactions
among sectors that make each region unique. Each represents a learning experience
that ultimately will lead to improvements in how regional assessments and integration
Box 8-4. Great Lakes-St. Lawrence Basin Project
|The Great Lakes-St. Lawrence Basin (GLSLB) Project on "adapting to the
impacts of climate change and variability" is a binational project initiated
in 1992 by Environment Canada to improve our understanding of the complex
interactions among climate, environment, and society so that regional adaptation
strategies could be developed in response to potential climate change and
variability (Mortsch and Mills, 1996). The GLSLB Project identified four
climate-sensitive theme areas upon which to focus the research: water use
and management, land use and management, ecosystem health, and human health.
Another prime focus of the GLSLB Project is adaptation, which provides the
conceptual framework for integrating research efforts. GLSLB Project studies
contain common components that will facilitate the integration of research
findings, including study objectives; policy issue foci; a multidisciplinary
approach; scenarios tested; impact and adaptation assessment methods; the
concept of adaptation; and scales of time, space, and human activity (Mortsch
and Mills, 1996). A number of more pragmatic integration concepts also have
been incorporated into the GLSLB Project, including the use of "end-to-end
studies" assessing biophysical and socioeconomic impacts and developing
and evaluating potential adaptation strategies, economic modeling (LINK
model), the use of Geographic Information Systems (GIS), and common communication
goals (Mortsch and Mills, 1996).