In 2015, with the signing of the BParis Agreement^, 195 countries committed to limiting the increase in global temperature to less than 2°C with respect to pre-industrial levels and to aim at limiting the increase to 1.5°C by 2100. The regional ramifications of those thresholds remain however largely unknown and variability in the magnitude of change and the associated impacts are yet to be quantified. We provide a regional quantitative assessment of the impacts of a 1.5 versus a 2°C global warming for a major global climate change hotspot: the Indus, Ganges, and Brahmaputra river basins (IGB) in South Asia, by analyzing changes in climate change indicators based on 1.5 and 2°C global warming scenarios. In the analyzed ensemble of general circulation models, a global temperature increase of 1.5°C implies a temperature increase of 1.4-2.6 (μ = 2.1)°C for the IGB. For the 2.0°C scenario, the increase would be 2.0-3.4 (μ = 2.7)°C. We show that climate change impacts are more adverse under 2°C versus 1.5°C warming and that changes in the indicators' values are in general linearly correlated to average temperature increase. We also show that for climate projections following Representative Concentration Pathways 4.5 and 8.5, which may be more realistic, the regional temperature increases and changes in climate change indicators are much stronger than for the 1.5 and 2°C scenarios.

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Direct selection for yield under drought has resulted in the release of a number of drought-tolerant rice varieties across Asia. In this study, we characterized physiological traits affected by that strategy in breeding trials across sites in Bangladesh, India, and Nepal. The drought breeding lines and drought-tolerant varieties showed consistently longer flag leaves and lower stomatal density than the drought-susceptible check, IR64. The influence of environmental parameters other than drought treatments on leaf traits was evidenced by the close grouping of treatments within a site. Flag leaf length and width appeared to be regulated by different environmental parameters. In separate trials in the Philippines, the same breeding lines studied in South Asia showed that canopy temperature under drought and harvest index across treatments were most correlated with grain yield. Both atmospheric and soil stress increased the relationship between leaf traits and yield. The stable expression of leaf traits among genotypes and the identification of the environmental conditions in which they contribute to yield, as well as the observation that some breeding lines showed longer time to flowering and higher canopy temperature than IR64, suggest that selection for additional physiological traits may result in further improvement of this breeding pool.

Bangladesh has been experiencing increased temperature and change in precipitation regime, which might adversely affect the important ecosystems in the country differentially. The river flows and groundwater recharge over space and time are determined by changes in temperature, evaporation and crucially precipitation. These again have a spatio-temporal dimension. This geospatial modeling research aimed at investigating spatial patterns and changing trends of temperature and rainfall within the geographical boundary of Bangladesh. This would facilitate better understanding the change pattern and their probable impacts on the ecosystem. The southeastern region, which is one of the most important forest ecosystem zones in the country, is experiencing early onset and withdrawal of rain but increasing trends in total rainfall except in the Monsoon season. This means that the region is experiencing a lower number of rainy days. However, total rainfall has not changed significantly. The differential between maximum and minimum showed an increasing trend. This changing pattern in average max and min temperature along with precipitation might cause a situation in which the species that are growing now may shift to suitable habitats elsewhere in the future. Consequently, the biodiversity, watersheds and fisheries, productivity of land, agriculture and food security in the region will be affected by these observed changes in climate.

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