A comparison of statistical downscaling and climate change factor methods: Impacts on low flows in the River Thames, United Kingdom

Strategic-scale assessments of climate change impacts are often undertaken using the change factor (CF) methodology whereby future changes in climate projected by General Circulation Models (GCMs) are applied to a baseline climatology. Alternatively, statistical downscaling (SD) methods apply climat...

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Bibliographic Details
Published in:Climatic change 2005-04, Vol.69 (2-3), p.245-268
Main Authors: DIAZ-NIETO, Jacqueline, WILBY, Robert L
Format: Article
Language:English
Subjects:
Case studies
Climate change
Climate science
Climatic conditions
Climatology
Climatology. Bioclimatology. Climate change
Comparative analysis
Earth sciences
Earth, ocean, space
Environmental assessment
Environmental impact
Evaporation
Evaporation rate
Exact sciences and technology
External geophysics
Freshwater
General circulation models
Hydrology
Hydrology. Hydrogeology
Local precipitation
Low flow
Meteorology
Methods
Precipitation
Realism
Rivers
Statistical methods
Summer
Temperature
Variables
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Summary:Strategic-scale assessments of climate change impacts are often undertaken using the change factor (CF) methodology whereby future changes in climate projected by General Circulation Models (GCMs) are applied to a baseline climatology. Alternatively, statistical downscaling (SD) methods apply climate variables from GCMs to statistical transfer functions to estimate point-scale meteorological series. This paper explores the relative merits of the CF and SD methods using a case study of low flows in the River Thames under baseline (1961-1990) and climate change conditions (centred on the 2020s, 2050s and 2080s). Archived model outputs for the UK Climate Impacts Programme (UKCIP02) scenarios are used to generate daily precipitation and potential evaporation (PE) for two climate change scenarios via the CF and SD methods. Both signal substantial reductions in summer precipitation accompanied by increased PE throughout the year, leading to reduced flows in the Thames in late summer and autumn. However, changes in flow associated with the SD scenarios are generally more conservative and complex than that arising from CFs. These departures are explained in terms of the different treatment of multidecadal natural variability, temporal structuring of daily climate variables and large-scale forcing of local precipitation and PE by the two downscaling methods. [PUBLICATION ABSTRACT]
ISSN:0165-0009
1573-1480
DOI:10.1007/s10584-005-1157-6