final_program_abstracts[1]

11 IMSC Session Program
Uncertainty propagation from climate change projections to
impacts assessments: Water resource assessments in South
America
Wednesday - Parallel Session 2
Hideo Shiogama 1 , Seita Emori 1,2 , Naota Hanasaki 1 , Manabu Abe 1 , Yuji
Masutomi 3 , Kiyoshi Takahashi 1 and Toru Nozawa 1
1
National Institute for Environmental Studies, Tsukuba, Japan.
2 Center for Climate System Research, University of Tokyo, Kashiwa, Japan
3 Center for Environmental Science in Saitama, Kisai Town, Japan.
Generally, climate change impact assessments are based on climate change
projections from coupled Atmosphere Ocean General Circulation Models
(AOGCMs). Therefore, uncertainties of climate change projections propagate to
impact assessments, and affect subsequent policy decisions. This study examined
uncertainty propagation from climate change projections to water resource
assessments in South America (SA). We applied Maximum Covariance Analysis
(dubbed Singular Value Decomposition analysis) to examine relationships between
global-scale uncertainties of climate changes and continental-scale uncertainties of
impact assessments. It was found that annual mean runoff in SA are sensitive to
changes in the Walker circulation (1st mode) and the Hadley circulation (2nd mode).
The 1st and 2nd modes of runoff changes are associated with intensities of the Walker
circulation and the Hadley circulation in the present climate simulations, respectively.
We also proposed a method to determine metrics associated with the leading runoff
modes. It was suggested that the ensemble mean water resource assessment (wetting
in the most of SA) is not the best estimate. Drying in the Amazon basin and wetting in
the La Plata basin are more reliable. Our finding may have great implications for
likelihood assessments of the dieback of the Amazon rainforest. This study would be
a good practice of interdisciplinary studies between IPCC WG1 and WG2.
Abstracts 186