Projected precipitation changes over the south Asian region for every 0.5 °C increase in global warming

Abstract

Using all ensemble members of NCAR CCSM4 for historical natural, RCP4.5 and RCP8.5 scenarios from CMIP5, we analyse changes in mean and extreme precipitation over the south Asian region for every 0.5 o C increase in global warming. An increase in mean annual precipitation is projected over majority of the south Asian region with increased levels of warming. Over Indian land, the spatiallyaveraged annual mean precipitation shows an increase in the range of~2-14 % based on the RCP scenario and level of warming. However, a decrease in mean annual precipitation is projected over northwest parts of the Indian sub-continent and the equatorial Indian Ocean with increased levels of warming. In general, we find multifold increase in the frequency of occurrence of daily precipitation extremes over the Indian subcontinent and surrounding oceans. Over Indian land, frequency of occurrence of daily precipitation extremes show up to three-fold increase under both RCP scenarios for global warming levels in the range of 1.5 o C-2.5 o C. With further increase in warming we find that the frequency of occurrence of daily precipitation extremes could show a massive four-to six-fold increase over majority of Indian land. Notably, unlike the projected increase in the frequency of occurrence of daily precipitation extremes, the projected change in annual mean precipitation is found to be insignificant in a 1.5 o C warmer world, over majority of the south Asian region, under both RCP scenarios. Given the projected large increase in frequency of daily precipitation extremes with increased levels of warming, our study provides scientific support to the recommendations of the Paris Agreement of 2015.

Intensification characteristics of hydroclimatic extremes in the Asian monsoon region under 1.5 and 2.0 °C of global warming

“…Consequently, the high-runoff extremes (i.e., MDF) are expected to increase by 3.4 % (0.3 %) under RCP4.5 (RCP8.5), which is likely to result in a risk of more intensified flooding. In contrast, the changes in the low-runoff extremes (DWF07 and DWF30) show low robust change signals in these regions as a result of small changes under a further 0.5 • C of global warming and substantial uncertainty in the GCM projections; this finding agrees with previous results (e.g., Chen et al, 2017;Donnelly et al, 2017;Marx et al, 2018). However, the change behavior in the hydroclimatic extremes (except for the low-runoff extremes) tends to be amplified at 2.0 • C of warming compared with 1.5 • C of warming regardless of the RCP.…”

“…On the other hand, RCP8.5 is a very high emission scenario with radiative forcing of approximately 8.5 W m −2 in 2100. Although the global warming process under RCP4.5, which is based on a mediumlow GHG emission pathway, is relatively slow compared to higher GHG emissions (e.g., RCP8.5), many studies have suggested that the global warming climate under RCP4.5 exerts impacts on hydroclimatic phenomena (Chen et al, 2017;Donnelly et al, 2017;Kim et al, 2020). However, global warming impacts under different RCPs on the regional changes in hydroclimatic extremes are not simple.…”

Synergistic impacts of anthropogenic fires and aridity on plant diversity in the Western Ghats: Implications for management of ancient social-ecological systems

“…those ignited by small-scale farmers who typically burn fallow land very locally, can spread over wide areas during exceptionally hot and dry years (Kodandapani et al, 2004;Cochrane, 2011;Silvério et al, 2019). The intensification of fires is particularly alarming in light of the projected weakening of the Indian Summer Monsoon (henceforth, monsoon), which is expected to excarbate rainfall extremeties in the Indian Subcontinent, extending the length of hot-dry months (Sinha et al, 2011;Roxy et al, 2015;Mishra et al, 2020 but see Bhowmick et al, 2019). Such enhanced regional aridity could mean drier fuel loads, resulting in more frequent spread of fires beyond agricultural lands.…”

Impacts of 1.5 °C and 2 °C global warming on regional rainfall and temperature change across India

“…Other than monsoon, South East India mostly receives it's rainfall from North East monsoon (October-December) and North West region also get significant rainfall during winters (Rajeevan et al (2012)). Even though the impact of global warming have been analyzed at all India level (Bhowmick et al 2019), there is not much information regarding specific 2°C and 1.5°C temperature rise on the regional climate change of India at the state level. Most of the climate change and adaptation plans are prepared at the state level and it would be relevant to understand the impacts of 2°C and 1.5°C global warming across the different states in India.…”