Temperature and precipitation projections over Bangladesh and the upstream Ganges, Brahmaputra and Meghna systems

Abstract

South Asia is a region of complex atmospheric dynamics and therefore changes resulting from increasing greenhouse gas concentrations, combined with existing vulnerability to extreme weather events such as flooding, could put the region at particular risk from climate change. However, current climate projections for the region show a range of uncertainty, particularly in terms of changes in the variability and extremes of precipitation. Focusing on Bangladesh and the region encompassing parts of the Ganges, Brahmaputra and Meghna river basins, we aim to explore and quantify climate model uncertainty in climate change projections for the 21(st) century. We use results from a 17-member perturbed physics ensemble of projections from a global climate model which have been used to drive a higher resolution (25 km) regional climate model over the south Asia region from 1971 to 2099. The range of temperature and precipitation responses across the ensemble are assessed including representation of the annual cycle, trends, and changes in precipitation extremes. The 17 ensemble members consistently simulate increasing annual mean temperatures by 2100 compared with present day, ranging between 2.6 °C and 4.8 °C. Additionally, all ensemble members indicate increasing annual precipitation by 2100 of between around 8% and 28%, though with interdecadal variability which results in one ensemble member showing a slight decrease in precipitation in the mid-century period. The frequency of light precipitation events is projected to decrease in the future, but with an increase in the frequency of heavy events. Three members of the climate model ensemble, representing a range of projected climate outcomes, have been selected for use in further impacts modelling for the region.

Modeling daily soil salinity dynamics in response to agricultural and environmental changes in coastal Bangladesh

“…In this work, we have used three different climate ensemble named Q0, Q8, and Q16. Daily precipitation and temperature values for 1981–2098 were provided by each ensemble of simulations of the HadRM3P (PRECIS) regional climate model developed by the Met Office Hadley Centre [ Caesar et al ., ]. The model is based on the HadCM3 global climate model and dynamically downscaled to assess regional climate variability.…”

Modelling the increased frequency of extreme sea levels in the Ganges–Brahmaputra–Meghna delta due to sea level rise and other effects of climate change

“…Three members of a 17-member perturbed physics ensemble (PPE) 27,28,29 were used, where these were selected to give a range of climate outcomes for the Bangladesh area. In the ESPA Deltas projct these have been used as three alternative scenarios of climate change, denoted as the Q0, Q8 and Q16 scenarios after their ensemble member names 14 . Q0 represents the unperturbed version of the model and Q8 and Q16 represent model versions which have increasingly higher global climate sensitivity, but none should be considered the most plausible and neither should they be considered as equally likely.…”

Total Basin Discharge From GRACE and Water Balance Method for the Yarlung Tsangpo River Basin, Southwestern China

“…The climate of YTR basin is dominated by the South Asia monsoon, which is the most prominent monsoon system of the world (Caesar et al, ; Dong et al, ; Song et al, ). As shown in Figure a, the precipitation exhibits clear seasonal variations under the influence of South Asia monsoon.…”