The global food system faces challenges from climate change and air pollution. Here, we examined their effects on rice yield in the North Indian plain (NIP), one of the principal rice-growing areas of the world. Combining satellite-based biophysical data products and spectral indices with soil moisture and fertilizer usage, we mapped high-resolution rice yield indiscriminately for both irrigated and rainfed systems in the NIP during the summer monsoon from 2004 to 2019. The footprints of meteorology and air pollution on the changing patterns of rice yield were isolated through multivariate linear models. The forced components of these models led to the estimation of relative yield change (RYC), the course of which was later simulated for the future climate change scenarios using CMIP6 data up to 2035. The largest effect on rice yield was estimated due to the variability of maximum temperature (−35 kg ha−1 to 212 kg ha−1) in the meteorological model, followed by aerosol loading (−80 kg ha−1 to 7 kg ha−1) in the air pollution model. The analysis of the RYC and its sensitivity using the CMIP6 climate change scenarios (SSP2 and SSP5) shows that among all agroclimatic regions, the Lower Gangetic Plain in the eastern NIP is resilient to the variability of meteorology and air pollution, while other agroclimatic regions – in the central and western NIP – show a remarkable reduction in their projected yields by 2035. The findings have serious implications for the supply chain and may increase pressure on the grain import due to climate change-driven future states of meteorology and air pollution.
Tag: aerosols
Wintertime characteristics of aerosols over middle Indo-Gangetic Plain: Vertical profile, transport and radiative forcing
Winter-specific characteristics of airborne particulates over middle Indo-Gangetic Plain (IGP) were evaluated in terms of aerosol chemical and micro-physical properties under three-dimensional domain. Emphases were made for the first time to identify intra-seasonal variations of aerosols sources, horizontal and vertical transport, effects of regional meteorology and estimating composite aerosol short-wave radiative forcing over an urban region (25°10–25°19N; 82°54–83°4E) at middle-IGP. Space-borne passive (Aqua and Terra MODIS, Aura OMI) and active sensor (CALIPSO-CALIOP) based observations were concurrently used with ground based aerosol mass measurement for entire winter and pre-summer months (December, 1, 2014 to March, 31, 2015). Exceptionally high aerosol mass loading was recorded for both PM10 (267.6 ± 107.0 g m 3) and PM2.5 (150.2 ± 89.4 g m 3) typically exceeding national standard. Aerosol type was mostly dominated by fine particulates (particulate ratio: 0.61) during pre to mid-winter episodes before being converted to mixed aerosol types (ratio: 0.41–0.53). Time series analysis of aerosols mass typically identified three dissimilar aerosol loading episodes with varying attributes, well resemble to that of previous year’s observation representing its persisting nature. Black carbon (9.4 ± 3.7 g m 3) was found to constitute significant proportion of fine particulates (2–27%) with a strong diurnal profile. Secondary inorganic ions also accounted a fraction of particulates (PM2.5: 22.5%; PM10: 26.9%) having SO4 2, NO3 and NH4+ constituting major proportion. Satellite retrieved MODIS-AOD (0.01–2.30) and fine mode fractions (FMF: 0.01–1.00) identified intra-seasonal variation with transport of aerosols from upper to middle-IGP through continental westerly. Varying statistical association of columnar and surface aerosol loading both in terms of fine (r; PM2.5: MODIS-AOD: 0.51) and coarse particulates (PM10: MODIS-AOD: 0.53) was found influenced by local meteorology (boundary layer and humidity) and aerosol vertical profile. A gradual increase in aerosol vertical profile (surface to 4.9 km) was evident with dominance of polluted continental, polluted dust and smoke at lower altitude. Presence of mineral dusts in higher altitude during later phase was linked with its transboundary transport, originating from western dry regions. Conclusively, winter-specific short-wave aerosol radiative forcing revealed an ATM warming effect (31–47 W m 2) while cooling both at TOA ( 20 to 32 W m 2) and SUF ( 51 to 80 W m 2) with significant level of intra-seasonal variations in heating rates (0.86–1.32 K day 1).
Assessing the spatial distribution of aerosols and air quality over the Ganga River basin during COVID-19 lockdown phase-1
The present study aims to analyze the variations in aerosol optical depth (AOD), black carbon (BC), organic carbon (OC), sulfate (SO4), dust, sea salt, fine mode dust and sea salt, and air quality over the Ganga River basin (GB), during the nation-wise lockdown phase-1 due to the outbreak of COVID-19. The aerosol data have been obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) and Modern-Era Retrospective analysis for Research and Applications (MERRA-2) for the lockdown phase-1 (March 25 – April 15, 2020) and its corresponding average of the reference period (2001-2019). The total PM2.5 has been modeled over the GB based on the inputs from MERRA-2. The in-situ air quality index (AQI) values from cities across the GB have been obtained during pre-lockdown (February, 29 – March 20, 2020) and lockdown phase-1 period to evaluate changes. Non-parametric pairwise comparison is performed to evaluate the significant change in the pollutants including AOD, and quantile regression is used to explore the effect of meteorology on AOD and other pollutants. The results show a significant reduction (p ≤ 0.05) in AOD, BC, OC, SO4, dust, dust particulate matter (PM2.5), sea salt, sea salt PM2.5, and estimated total PM2.5 during the lockdown phase-1 with respect to the reference period. The analysis also reveals that meteorological factors do not play a vital role in the reduction of AOD during the lockdown phase-1 period. The estimated reductions for AOD, BC, OC, SO4, dust, dust PM2.5, sea salt, and sea salt PM2.5 are 33%, 21%, 24%, 20%, 18%, 17%, 64%, and 61%, respectively due to imposition of lockdown measures. As many as 28 cities in the GB have shown substantial improvement in the air quality during the lockdown phase-1 period. The reduction in the emission quantity and subsequent improvement in AQI has opened up a new discourse for combatting the persistent air quality issues for million-plus cities in particular and for the north Indian plain in general. The findings of this study thus provide insightful views to the environmentalists and policymakers for framing better emission policy to deal with the air quality issue.