THE ABSENCE OF A ROLE OF CLIMATE CHANGE IN THE 2011 THAILAND FLOODS
Geert Jan van Oldenborgh—KNMINMINMI, De Bilt, Netherlands; Anne van Urk—CoDeWa, Reeuwuwijkjk, Netherlands; Myles Allen—Atmospheric, Oceanic and Planetary Physics, Department of Physics, and Environmental Change Instituttuttute, School of Geography and the Environment, University of Oxford, Oxford, United Kingdom
Thailand experienced severe flooding in 2011. During and after an unusually wet monsoon (July–September) in northern Thailand, rivers on the flood plains in the center and the south flooded their banks and inundated large parts of the country, including the former capital Ayuttha and neighborhoods of the present capital Bangkok. Large-scale industrial estates were submerged by 2.5 m of water for nearly 2 months and the economic damage was considerable. The reinsurer SwissRe estimated an insured damage between 8 and 11 billion U.S. dollars (USD) (SwissRe 2011). The total damage is much more uncertain, the World Bank estimates a value of 45 billion USD (World Bank 2011).
Flooding events are not uncommon in Thailand. However, the scale of the 2011 event was unprecedented. In this article we perform a first analysis of the meteorological component of the flood: how unusual was the rainfall in the catchment of the Chao Phraya river in northwestern Thailand, and are future monsoon rainfall trends expected due to climate change? It should be emphasized, however, that nonmeteorological factors were much more important in setting the scale of the disaster. Examples are the changing hydrography of the river (the levels of the Chao Phraya were in some places more than 0.5 m higher than in 1995 for even a slightly lower discharge), conversion of agricultural land to much more vulnerable industrial usage, and reservoir operation policies.
AMERICAN METEOROLOGICAL SOCIETY JULY 2012
