Populations that inhabit small islands and low-lying
coastal areas are at particular risk of severe social and economic effects
from sea-level rise and storm surges. Tens of millions of people
living in deltas, low-lying coastal areas, and on small islands will face
risk of displacement. Further negative impacts will be increased by saltwater
intrusion and flooding due to storm surges and loss of coastal wetlands
and slowing down of river discharges.
Key uncertainties in the identification and quantification
of impacts arise from the lack of reliable local or regional detail in
climate change, especially in the projection of extremes, inadequate accounting
in impacts assessments for the effects of changes in extremes and disasters,
limited knowledge of some non-linear processes and feedbacks, uncertainties
in the costing of the damage due to climate impacts, lack of both relevant
data and understanding of key processes in different regions, and uncertainties
in assessing and predicting the response of ecological and social (e.g.,
impact of vector- and water-borne diseases), and economic systems to the
combined effect of climate change and other stresses such as land-use
change, local pollution, etc.
||Costs and Benefits
of Adaptation and Mitigation Options
||Adaptation is a necessity;
its cost can be reduced by anticipation, analysis, and planning.
|| Adaptation is no longer an option, it
is a necessity, given that climate changes and related impacts are already
occurring. Anticipatory and reactive adaptation, which will vary with location
and sector, has the potential to reduce adverse impacts of climate change,
to enhance beneficial impacts, and to produce many immediate ancillary benefits,
but will not prevent all damages. However,
its potential is much more limited for natural systems than for human systems.
The capacity of different regions to adapt to climate change depends highly
upon their current
and future states of socio-economic development and their exposure to climate
stress. Therefore the potential for adaptation is more limited for developing
countries, which are projected to be the most adversely affected. Adaptation
appears to be easier if the climate changes are modest and/or gradual rather
than large and/or abrupt. If climate changes more rapidly than expected
in any region, especially with respect to climate extremes, then the potential
of adaptation to diminish vulnerability of human systems will be lessened.
Q3.26-28 & Q3.33
||The costs of adaptation can be reduced
by anticipation and planned action, and many costs may be relatively small,
especially when adaptation policies and measures contribute to other goals
of sustainable development.
Q3.31 & Q3.36-37
||Key uncertainties regarding adaptations relate
to the inadequate representation by models of local changes, lack of foresight,
inadequate knowledge of benefits and costs, possible side effects including
acceptability and speed of implementation, various barriers to adaptation,
and more limited opportunities and capacities for adaptation in developing