4.8.3. Adapting to Climate Change
Water managers are beginning to consider adapting to climate change. Somebut
not allwater management plans and infrastructure have long lead times
and long design lives. Improved understanding of the science of
climate change impacts in the water sector is important but is not in itself
enough to enable efficient adaptation. This is because it will never be feasible
to base decisions on just one future climate scenario, particularly for time
horizons greater than a decade. This is partly a result of incomplete knowledge
but largely because of inherent uncertainty in future emissions of GHGs. Therefore,
water managers always will be dealing with a range of scenarios, and research
aimed at enabling efficient adaptation consequently must focus largely on appropriate
analytical and management tools to cope with uncertainty and change rather than
on improving climate change science and scenarios per se. In some
aspects of water managementparticularly associated with water qualityscientific
research into processes is fundamental to allowing efficient adaptation.
Efficient adaptation to climate change in the water sector requires effort
in five main areas:
- Data for monitoring. Adaptive water management requires reliable data on
which to make decisions, calibrate models, and develop projections for the
future. These data should cover not just hydrological characteristics but
also indicators of water use.
- Understanding patterns of variability. An understanding of patterns of variabilityin
particular, the stability of a baseline climateis important
for medium-term water management. It is increasingly recognized that even
in the absence of climate change, the recent past may not be a reliable guide
to the hydrological resource base of the near future.
- Analytical tools. Effective water management requires numerous tools to
assess options and the future. These tools include scenario analysis and risk
analysis, which are used in some parts of water management but currently are
by no means widespread.
- Decision tools. Scenario and risk analysis provides information on possible
futures and their consequences. They must be supplemented with tools such
as Bayesian and other decisionmaking tools to make decisions on the basis
of the information provided. Again, techniques for decisionmaking under uncertainty
are not widely used in water management at present, and some of the approaches
being used are not very sophisticated.
- Management techniques. These are the techniques that are actually implemented
to meet management objectives. The broad spectrum of techniques (such as building
a reservoir or managing demand) is well known, but there is a need for research
into specific aspects of many demand-side approaches in particular, as well
as into opportunities for seasonal flow forecasting and innovative water supply
and treatment technologies (such as desalination). It also is necessary to
undertake research to determine how to enhance the range of techniques considered
by water managers.
Note that the above efforts are needed to improve water management even in
the absence of climate change, and there is an overarching need to improve the
exchange of information between hydrological science and water managers.
Water managers have long been accustomed to dealing with change, although until
recently this has been primarily change resulting from changes in demand and
altered legislative or statutory requirements. Climate change does not in itself
stimulate development of new adaptive strategies, but it encourages a more adaptive,
incremental, risk-based approach to water management. More precisely, it provides
further encouragement for a trend that already is gathering pace.