8. Information Needs
Although progress has been made, considerable gaps in knowledge remain regarding
exposure, sensitivity, adaptability, and vulnerability of physical, ecological,
and social systems to climate change. Advances in these areas are priorities
for advancing understanding of potential consequences of climate change for
human society and the natural world, as well as to support analyses of possible
responses.
Exposure. Advances in methods for projecting exposures to climate stimuli
and other nonclimate stresses at finer spatial scales are needed to improve
understanding of potential consequences of climate change, including regional
differences, and stimuli to which systems may need to adapt. Work in this area
should draw on results from research on system sensitivity, adaptability, and
vulnerability to identify the types of climate stimuli and nonclimate stresses
that affect systems most. This research is particularly needed in developing
countries, many of which lack historical data, adequate monitoring systems,
and research and development capabilities. Developing local capacity in environmental
assessment and management will increase investment effectiveness. Methods of
investigating possible changes in the frequency and intensity of extreme climate
events, climate variability, and large-scale, abrupt changes in the Earth system
such as slowing or shutdown of thermohaline circulation of oceans are priorities.
Work also is needed to advance understanding of how social and economic factors
influence the exposures of different populations.
Sensitivity. Sensitivity to climate stimuli is still poorly quantified
for many natural and human systems. Responses of systems to climate change are
expected to include strong nonlinearities, discontinuous or abrupt responses,
time-varying responses, and complex interactions with other systems. However,
quantification of the curvature, thresholds, and interactions of system responses
is poorly developed for many systems. Work is needed to develop and improve
process-based, dynamic models of natural, social, and economic systems; to estimate
model parameters of system responses to climate variables; and to validate model
simulation results. This work should include use of observational evidence,
paleo-observations where applicable, and long-term monitoring of systems and
forces acting on them. Continued efforts to detect impacts of observed climate
change is a priority for further investigation that can provide empirical information
for understanding of system sensitivity to climate change
Adaptability. Progress has been made in the investigation of adaptive
measures and adaptive capacity. However, work is needed to better understand
the applicability of adaptation experiences with climate variability to climate
change, to use this information to develop empirically based estimates of the
effectiveness and costs of adaptation, and to develop predictive models of adaptive
behavior that take into account decision making under uncertainty. Work also
is needed to better understand the determinants of adaptive capacity and to
use this information to advance understanding of differences in adaptive capacity
across regions, nations, and socioeconomic groups, as well as how capacity may
change through time. Advances in these areas are expected to be useful for identifying
successful strategies for enhancing adaptation capacity in ways that can be
complementary to climate change mitigation, sustainable development, and equity
goals.
Vulnerability. Assessments of vulnerability to climate change are largely
qualitative and address the sources and character of vulnerability. Further
work is needed to integrate information about exposures, sensitivity, and adaptability
to provide more detailed and quantitative information about the potential impacts
of climate change and the relative degree of vulnerability of different regions,
nations, and socioeconomic groups. Advances will require development and refinement
of multiple measures or indices of vulnerability such as the number or percentage
of persons, species, systems or land area negatively or positively affected;
changes in productivity of systems; the monetary value of economic welfare change
in absolute and relative terms; and measures of distributional inequities.
Uncertainty. Large gaps remain in refining and applying methods for
treating uncertainties, particularly with respect to providing scientific information
for decisionmaking. Improvements are required in ways of expressing the likelihood,
confidence, and range of uncertainty for estimates of outcomes, as well as how
such estimates fit into broader ranges of uncertainty. Methods for providing
"traceable accounts" of how any aggregated estimate is made from disaggregated
information must be refined. More effort is needed to translate judgments into
probability distributions in integrated assessment models.
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