What the study found
The study found that an eight-member ensemble, called AMME8, gave the best overall match to observed precipitation extremes in the Kosi River Basin. It also found that future precipitation extremes are projected to intensify under both SSP245 and SSP585, with the strongest increases in the far future under SSP585.
Why the authors say this matters
The authors conclude that reliable regional climate projections are important for water resource planning and climate adaptation strategies. The study suggests that evaluating climate models by precipitation index and forming an optimal ensemble can improve confidence in regional projections.
What the researchers tested
The researchers evaluated thirteen statistically downscaled and bias-corrected CMIP6 Global Climate Models, which are climate models used in the Coupled Model Intercomparison Project. They tested the models against eight ETCCDI precipitation indices using eight statistical indicators, weighted by the CRITIC method, and then ranked them with TOPSIS, VIKOR, EDAS, and PROMETHEE-II.
What worked and what didn't
MPI-ESM1-2-HR, INM-CM5-0, and BCC-CSM2-MR consistently performed better than the other models. ACCESS-CM2 and NorESM2 variants showed weaker agreement, and AMME8 produced the best balance of accuracy and uncertainty reduction, closely reproducing observed relationships among precipitation extremes and achieving the optimal symmetric uncertainty.
What to keep in mind
The summary does not describe limitations beyond noting uncertainty among CMIP6 models. The projection results are specific to the Kosi River Basin and to the models, indices, and ensemble choices used in this study.
- Thirteen downscaled, bias-corrected CMIP6 models were assessed for precipitation extremes in the Kosi River Basin.
- AMME8, an eight-member ensemble, gave the best overall balance of accuracy and uncertainty reduction.
- MPI-ESM1-2-HR, INM-CM5-0, and BCC-CSM2-MR performed best; ACCESS-CM2 and NorESM2 variants performed more weakly.
- Future projections indicated intensified precipitation extremes under both SSP245 and SSP585.
- Under SSP585 in 2061–2100, increases were projected of up to 47% in annual precipitation, 60% in heavy rainfall days, and nearly 79% in extremely wet days.