Using the simple anomaly method (modifying a historical baseline with
differences or ratios projected by General Circulation Models),
scientists from the California Academy of Sciences downscaled monthly
total precipitation from 16 different global circulation models
(GCMs). The GCMs were described in the latest Intergovernmental Panel
for Climate Change (IPCC 2007) and archived at the WCRP PCMDI (
http://www-pcmdi.llnl.gov/ipcc/about_ipcc.php).
Monthly total precipitation was downscaled using the ratio between
each 20 year-period in the future (e.g. 2040-2059) and the simulated
historical average (1950-2000) from each GCM. Each layer was then
interpolated to a spatial grain of 10x10 km2 using the regularized
spline function of Spatial Analyst tool in ArcGIS 9.3, and then
multiplied by the baseline historical climate (Wordclim 1.4) to create
future projected precipitation: Pdw=((Pf/Pc )*Pobs )
Monthly
precipitation was averaged seasonally over 20 year periods of GCM
simulations from 2000 through 2099. Seasonal climate means were
generated by averaging values for three months (ex. winter
conditions correspond to the average climate for
December,
January,
February). Two
sets of future climate projections are available, corresponding to
either the regional economic A2 or the global environmental and
equitable B1 greenhouse gas emissions scenarios. Every data layer has
a corresponding layer representing the standard deviation across GCMs,
which gives an estimate of the variability of the climate across the
various GCMs (16 for precipitation) used to calculate the average.
Related datasets and documentation can be found in the Databasin gallery at: http://app.databasin.org/app/pages/galleryPage.jsp?id=2a47360040364876b37a52657793faa6
I am a biodiversity scientist interested in understanding and conserving the diversity of life at multiple evolutionary and spatial scales. As Chief Scientist at Natureserve, I lead a talented and dedicated team of ecologists, taxonomists, and biodiversity information scientists in the application...