Options for Improving Climate Modeling to Assist Water Utility ...

Water Utility Climate Alliance White Paper
Options for Improving Climate Modeling to Assist Water Utility Planning for Climate Change
created additional CMIP3 archives, containing data suitable for RCMs and statistical
downscaling.
4. Reduce the range of climate projections where possible.
5. Address the climate information needed for water utilities planning; however, DS-1 may
have a much wider impact so long as decision-makers and experts from other fields were
involved early in its implementation.
Following are three standalone investment options for improving the actionability of downscaled
climate change projections. Although the expected benefits of investment in each option are not
dependent on investment in other options, synergistic benefits may be incurred if more than one
investment option is pursued. It should also be recognized that some of the activities described in
the investment options are ongoing, and that additional investments primarily affect the scale of
the effort, which should accelerate the ongoing work.
DS-1. Develop regional and local climate change ensembles
This option will produce large ensembles of local projections by combining the strengths of
statistical and dynamical downscaling, using RCMs at a resolution that is both scientifically
justifiable and relevant to water utility planning and statistical downscaling techniques for
relevant variables. Although some improvement in representing regional climate processes is
expected by reducing RCM resolution, this investment option addresses primarily the lack of
infrastructure to perform the simulations, coordinate the work, and distribute the results. The
main benefit will be a vast improvement in understanding how uncertainty arises in local
projections, what confidence can be placed in them, and how uncertainty and confidence can be
effectively articulated to water utilities. All of the components needed to produce this dataset are
in existence.
It should also be noted that the cost of this option can be trimmed considerably, particularly in
the costs for computing facilities and external grant programs, by focusing only on the statistical
downscaling portion.
Perform RCM simulations that conform to the evaluation strategy in Section 3.2.5
(baseline climate simulation, alternative baseline climate simulation, historic simulation,
future projection) using multiple RCMs with grid spacing in the range of 10–20 km.
Ideally, this would be coupled with investment option GCM-1, and the framework of
COREDEX would be used as guidance. An alternative approach is to build on existing
programs through an expansion of the NARCCAP.
Page 4-16