Articles | Volume 4, issue 2
Earth Syst. Dynam., 4, 359–374, 2013

Special issue: Intersectoral Impact Model Intercomparison Project (ISI-MIP)

Earth Syst. Dynam., 4, 359–374, 2013

Research article 10 Oct 2013

Research article | 10 Oct 2013

Comparing projections of future changes in runoff from hydrological and biome models in ISI-MIP

J. C. S. Davie1, P. D. Falloon1, R. Kahana1, R. Dankers1, R. Betts1, F. T. Portmann2,9, D. Wisser3, D. B. Clark4, A. Ito5, Y. Masaki5, K. Nishina5, B. Fekete6, Z. Tessler6, Y. Wada7, X. Liu8, Q. Tang8, S. Hagemann10, T. Stacke10, R. Pavlick11, S. Schaphoff12, S. N. Gosling13, W. Franssen14, and N. Arnell15 J. C. S. Davie et al.
  • 1Met Office Hadley Centre, Exeter, UK
  • 2Biodiversity and Climate Research Centre (LOEWE BiK-F) & Senckenberg Research Institute and Natural History Museum, Frankfurt am Main, Germany
  • 3Center for Development Research, University of Bonn, Germany
  • 4Centre for Ecology and Hydrology, Wallingford, UK
  • 5Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan
  • 6Civil Engineering Department, The City College of New York CUNY, New York, USA
  • 7Department of Physical Geography, Faculty of Geosciences, Utrecht University, the Netherlands
  • 8Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
  • 9Institute of Physical Geography, Goethe University Frankfurt, Frankfurt am Main, Germany
  • 10Max Planck Institute for Meteorology, Hamburg, Germany
  • 11Max Planck Institute for Biogeochemistry, Jena, Germany
  • 12Potsdam Institute for Climate Impact Research, Potsdam, Germany
  • 13School of Geography, University of Nottingham, Nottingham, UK
  • 14Wageningen University and Research Centre, Wageningen, the Netherlands
  • 15Walker Institute, University of Reading, UK

Abstract. Future changes in runoff can have important implications for water resources and flooding. In this study, runoff projections from ISI-MIP (Inter-sectoral Impact Model Intercomparison Project) simulations forced with HadGEM2-ES bias-corrected climate data under the Representative Concentration Pathway 8.5 have been analysed for differences between impact models. Projections of change from a baseline period (1981–2010) to the future (2070–2099) from 12 impacts models which contributed to the hydrological and biomes sectors of ISI-MIP were studied. The biome models differed from the hydrological models by the inclusion of CO2 impacts and most also included a dynamic vegetation distribution. The biome and hydrological models agreed on the sign of runoff change for most regions of the world. However, in West Africa, the hydrological models projected drying, and the biome models a moistening. The biome models tended to produce larger increases and smaller decreases in regionally averaged runoff than the hydrological models, although there is large inter-model spread. The timing of runoff change was similar, but there were differences in magnitude, particularly at peak runoff. The impact of vegetation distribution change was much smaller than the projected change over time, while elevated CO2 had an effect as large as the magnitude of change over time projected by some models in some regions. The effect of CO2 on runoff was not consistent across the models, with two models showing increases and two decreases. There was also more spread in projections from the runs with elevated CO2 than with constant CO2. The biome models which gave increased runoff from elevated CO2 were also those which differed most from the hydrological models. Spatially, regions with most difference between model types tended to be projected to have most effect from elevated CO2, and seasonal differences were also similar, so elevated CO2 can partly explain the differences between hydrological and biome model runoff change projections. Therefore, this shows that a range of impact models should be considered to give the full range of uncertainty in impacts studies.

Final-revised paper