For the Lower Mekong Basin (LMB), defining and application of future climate change scenarios are one of the most critical steps in climate change impact assessment and adaptation planning. Related to the LMB, numerous climate change impact studies have been undertaken. These studies have employed different climate change scenarios and estimate climate change impacts for either the wider region that the LMB is located within, the LMB as a whole or the countries, regions or catchments within the LMB. The Mekong River Commission (MRC) previously used results from one GCM (ECHAM4 from the Max Planck Institute for Meteorology, Germany) and two emission scenarios A2 and B2 (of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES)) in a first assessment of projected changes to flow regimes in the Mekong (MRC, 2010). The PRECIS (Providing REgional Climates for Impacts Studies) was used to obtain dynamically downscaled climate projections. In a follow up study (MRC, 2011) the MRC Information and Knowledge Management Programme (IKMP) built on the MRC (2010) work by also taking into account sea level rise of 17 cm by 2030 and 30 cm by 2060. Other non-MRC studies used different GCMs and different emission scenarios (CCAI, 2015).