10.4122/1.1000000555
Ahlfeld, David
David
Ahlfeld
ahlfeld@ecs.umass.edu
Ahlfeld, David
David
Ahlfeld
ahlfeld@ecs.umass.edu
Can Global Climate Models be Used for Water Resource Planning?
XVI International Conference on Computational Methods in Water Resources
2006
2006
Water resources planning is needed to adapt to a changing climate. As precipitation,
wind and temperature patterns shift, water availability and demand by humans and
other ecosystems will change. These shifts have the potential to impact water
supply, agriculture, forestry and all non-human natural systems. Many large scale
water resource projects, such as reservoirs, distribution systems, groundwater
recharge facilities and desalinization systems can take many years to plan and
construct. Shifting the location of agricultural activities may also require large
lead times. Models are needed to predict climate one or more decades into the future
to assist in rational planning of water resource systems as water needs change. It
is important that these models predict trends at the decadal time scale, but also
provide an indication of the permanence of these changes to distinguish changes which
are permanent rather temporary excursions from the climate under which industrial
civilization has evolved.
Global Climate Models (GCM) and Regional Climate Models (RCM) have the potential to
be useful tools for water resource planning under a changing climate. GCMs have been
under development for many years with a primary goal of quantifying the long-term
impact, on climate, of emissions of greenhouse gases. The focus has been on global
average conditions. RCMs are a more recent development that seek to model climate at
finer grid scales and shorter time frames. Several major RCM projects are under
development including those that focus on North America and Europe.
In the present study, an intercomparison study is conducted of the ability of GCMs to
replicate observed 20th century climate. In addition, the GCMs are examined for
their ability to provide meaningful results at different spatial scales. Comparisons
are made with the CMAP observed precipitation data set which covers the period
1979-2000. GCM results are acquired from the IPCC database maintained by the Program
for Climate Model Diagnosis and Intercomparison at LLNL. A comparison is made in
three regions of North America. An additional comparison is conducted over a series
of successively smaller averaging regions in portions of eastern North America.
Precipitation and temperature averaged over monthly, seasonal and annual time periods
is considered. Most models compare well with observed precipitation for the central
and eastern regions at all time scales. For the western region, all models
over-predict precipitation at most time scales both for the entire averaging region
and for subdivisions of the region.