|
1.1. Scope of the Assessment
Worldwide concern about possible climate change and acceleration of sea-level
rise resulting from increasing concentrations of greenhouse gases has led governments
to consider international action to address the issue, particularly through
the development of the United Nations Framework Convention on Climate Change
(UNFCCC). Because the extent and urgency of action required to mitigate the
source of the problem-namely the emission of greenhouse gases by human activities-depends
on the level of vulnerability, a key question for the Conference of the Parties
(COP) to the Convention, and for policymakers in general, is the degree to which
human conditions and the natural environment are vulnerable to the potential
effects of climate change. Impact assessments are needed to establish the costs
and benefits of climatic change as a guide to what adaptation and mitigation
measures might be justified. Without such assessments, we run the risk of making
uninformed, unwise, and perhaps unnecessarily costly decisions.
The foundation for policy formulation for the climate change problem is scientific
information on greenhouse gas emissions, the climate system and how it may change,
and the likely impacts on human activities and the environment. To provide the
best available base of scientific information for policymakers and public use,
governments have requested that the Intergovernmental Panel on Climate Change
(IPCC) periodically assess and summarize the current scientific literature related
to climate change. The most recent assessment is the Second Assessment Report
(SAR), a comprehensive three-volume report completed in 1995 and published in
1996. This assessment involved extensive inputs from thousands of scientists
and was reviewed by governments and leading experts. The SAR takes a global
view of the impacts of climate change, organizing chapters by ecosystem type
or socioeconomic sector (e.g., forests, grasslands, agriculture, and industry).
In making use of the SAR, the UNFCCC negotiators found a need for more explicit
information on how different regions of the world might be affected, to better
assess their degrees of vulnerability. Accordingly, the Subsidiary Body for
Scientific and Technological Advice (SBSTA) of the UNFCCC requested that the
IPCC prepare a report that provided a geographically explicit view of the problem,
particularly the vulnerabilities for each region. Initially, a Technical Paper
was planned (which, under the IPCC rules of procedure, limited the authors to
citing only material included in the SAR), but in September 1996 the IPCC XIIth
Plenary at Mexico City decided that a Special Report should be produced. This
decision was taken to allow the inclusion and proper review of new material
post-dating the SAR-especially new work emerging from several country studies
programs, as well as regional studies which were not included in the SAR due
to its global scope.
The present report is the result of this process. This report provides assessments
of vulnerability of climate change for 10 regions of the globe: Africa, the
Arctic and the Antarctic (Polar Regions), Australasia, Europe, Latin America,
Middle East and Arid Asia (Arid Western Asia), North America, Small Island States,
Temperate Asia, and Tropical Asia. It also includes several annexes that provide
information about climate observations, climate projections, vegetation distribution
projections, and socioeconomic baseline assumptions used in the report.
1.2. Approach of the Assessment
This report should be read as an assessment of the scientific and technical
literature related to the sensitivity, adaptability, and vulnerability of ecosystems
and social and economic sectors in the 10 regions-not as a quantitative integrated
assessment of impacts. The approach used in preparing the assessment was agreed
by the lead authors at a series of scoping meetings held in Washington, DC,
in May and September 1996, which set the direction of the assessment when it
was being prepared as a technical paper. These meetings were used to review
materials from the sectoral assessments of the SAR and organize them into regional
analyses, and to identify common issues across the regions and standardize approaches
to addressing them. After the paper was reprogrammed as a special report, a
series of chapter-specific regional consultations and meetings of lead authors
and other experts was held to refine the scope of each regional assessment and
to identify studies and methods to use in addition to those used in the SAR.
These meetings were held in Toronto, Canada (13-15 January 1997); New Delhi,
India (23-25 January 1997); Harare, Zimbabwe (27-29 January 1997); Tarawa, Kiribati
(10-13 February 1997); Montevideo, Uruguay (11-13 February 1997); and Amsterdam,
The Netherlands (19-21 March 1997).
On the basis of these meetings, the lead authors set about preparing each chapter
to provide an assessment of the vulnerability of natural ecosystems, socioeconomic
sectors, and human health in the region. The definition of vulnerability used
in the SAR was adopted for use by the lead authors in this report: "Vulnerability"
is the extent to which climate change may damage or harm a system; it is a function
of both the "sensitivity" of a system or structure to climate and the opportunities
for "adaptation" to new conditions. Sensitivity is defined as the degree to
which a system will respond to a change in climatic conditions (e.g., the extent
of change in ecosystem composition, structure, and functioning, including primary
productivity, resulting from a given change in temperature or precipitation).
The responses may result in either beneficial or harmful effects. Adaptation
is defined as adjustments in practices, processes, or structures in response
to projected or actual changes in climate. Adjustments can be either spontaneous
or planned, reactive or anticipatory. In some cases (e.g., for many ecosystems),
options for planned or anticipatory adaptation may not exist. Adaptations can
reduce negative impacts or take advantage of new opportunities presented by
changing climate conditions. It is in part because of the uncertainties associated
with regional projections of climate change (these uncertainties are summarized
in Section 1.3.2. and described more fully in Annex
B) that this report takes the approach of assessing vulnerabilities, rather
than quantitatively assessing expected impacts of climate change.
This report is based upon evidence found in the published literature, which
uses a diverse range of methods and models. This diversity reflects current
uncertainties regarding the functioning of complex natural and social systems
and how they respond to changes in climate. The assessment did not include the
performance of new research or computer model simulations by the authors to
estimate impacts under common scenarios of greenhouse gas emissions or climate
change. Such work was beyond the scope of the report. Because the available
studies have not employed a common set of climate scenarios, and because of
uncertainties regarding the sensitivity and adaptability of natural and social
systems, the assessment of regional vulnerabilities is necessarily qualitative.
Often only very general conclusions can be supported by the currently available
evidence. In a number of instances, quantitative estimates of impacts of climate
change are cited in the report. Such estimates are strongly dependent upon the
specific assumptions made and models used. These estimates should not be interpreted
as predictions of the most likely impacts, but rather as illustrations of the
potential character and magnitude of impacts that may result from specific scenarios
of climate change.
Many impacts studies use model simulations for the equilibrium climatic response
to a carbon dioxide (CO2) doubling, rather than more recent model simulations
of climate change resulting from gradually increasing CO2 concentrations and
changing concentrations of aerosols and stratospheric ozone. Thus the level
of warming used in many of the impacts studies may not be reached until several
decades after 2100, rather than by that date. However, this does not necessarily
mean that all impacts will be slowed; for example, the transient simulations
exhibit larger land-sea temperature change contrasts, and this would be expected
to alter atmospheric circulation and weather patterns in ways not predicted
in the equilibrium simulations. Historical observations of the impacts of weather
patterns-including droughts, floods, storms, and other extreme weather events-suggest
that changes in climate variability could have important impacts on natural
and social systems.
Some readers of the special report will be interested only in a particular
region, whereas others will be interested in comparing information from different
regions. To facilitate such comparison, a common structure, or template, for
each regional chapter was developed. The main elements of this chapter template
follow:
Executive Summary
Regional Characteristics
- Biogeography (countries, ecosystems, socioeconomic activities covered)
- Trends (key socioeconomic and resource-use information based on data from
existing international sources, compiled by the Technical Support Unit in
cooperation with World Resources Institute)
- Major climatic zones
- Observed trends for temperature and precipitation (based on IPCC, 1996,
WG I, Chapter 3, extended and updated to cover a broader number of contiguous
regions)
- Summary of available information on projections of future climate (based
on IPCC, 1996, WG I, Chapter 6) and including updated material specific to
the region used in regional impact assessments
Sensitivity, Adaptability, and Vulnerability
- Coverage of topics in this section will vary by region, depending on the
most important sectors for each region; however, chapters organize the information
into the following categories:
- Ecosystems (including biodiversity)
- Hydrology/water supply
- Food and fiber for human consumption (agriculture, forestry, and fisheries)
- Coastal systems
- Human settlements and urbanization
- Human health
- Other topics particularly relevant to each region (e.g., energy, transport,
tourism)
Integrated Assessment of Potential Impacts
- Assessments of illustrative case examples related to ecosystems, water supply/basin
management, and socioeconomic activities
- Integrated model results, if available
- Lessons from past fluctuations/variability
This approach is broadly consistent with the seven-step method outlined by
the IPCC in its Technical Guidelines for Assessing Climate Change Impacts and
Adaptations (IPCC, 1994b). These steps are: 1) defining the problem; 2) selecting
the method; 3) testing the method/sensitivity; 4) selecting scenarios; 5) assessing
biophysical/socioeconomic impacts; 6) assessing autonomous adjustments; and
7) evaluating adaptation strategies.
|