Model Uncertainty in the Projected Indian Summer Monsoon Precipitation Change under Low-Emission Scenarios

The projected ISM precipitation changes under low-emission scenarios, Representative Concentration Pathway 2.6 (RCP2.6) and Shared Socioeconomic 1-2.6 (SSP1-2.6), are investigated by outputs from models participating in phases 5 6 of the Coupled Model Intercomparison Project (CMIP5 CMIP6). Based on high-emission scenarios like RCP8.5, Intergovernmental Panel Climate Change Fifth Assessment Report suggests a wetter Indian summer monsoon (ISM) end 21st century. Although multi-model ensemble mean (MME) RCP2.6 SSP1-2.6 is still to increase over 2050–2099 referenced 1900–1949, intermodel spread change tremendous both CMIPs. Indeed, signal-to-noise ratio (SNR) change, defined as MME divided its standard deviation, even below 1 scenarios. This casts doubts future warmer climate. Moisture budget analyses further show that most model uncertainty caused dynamical component atmospheric circulation change. As expected, interhemispheric surface warming contrast essential causing differences In addition, prominently enhanced CMIP5 CMIP6, along with reduced uncertainty. However, resultant increased SNR CMIP6 low regions. results imply highly uncertain which greatly challenges decisions-making adaptation policies for densely populated South Asian countries.