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In this paper, changes in the long and short spells of different rain intensities are statistically analyzed using daily gridded rainfall data prepared by the India Meteorological Department for the period 1951-2008. In order to study regional changes, analyses have been conducted over nine selected agro-meteorological (agro-met) divisions, five homogeneous zones, and also over the whole of India. Rain events of different intensities with continuous rainfall of more than or equal to 4 days are classified here as long spells. Those with less than 4 days are termed as short spells. Those results which are statistically significant at 95% confidence level are discussed in this paper. Trend analysis shows that during the summer monsoon months of June to September, short spell rain events with heavy intensity have increased over India as a whole. On the other hand, long spell rain events with moderate and low intensities have decreased in numbers. Results further show that the contributions of long spell moderate and short spell low-intensity rain events to the total rainfall have decreased whereas the contributions of short spell heavy and moderate-intensity rain events to the total seasonal rainfall have increased. Percentage changes in various categories of long and short spells in the decade 1991-2000 compared with the earlier decade 1951-1960, highlight the maximum increase in heavy-intensity short spell category and decrease in moderate-intensity long spell category in India as a whole and in most of the homogeneous zones and agro-met divisions. The changes in different types of rain events differ in the six homogeneous zones and nine selected agro-met divisions. However, in three homogeneous zones and three agro-met divisions, the short spell heavy-intensity rain events dominate as in the entire country. There are also changes observed in the monthly occurrences of above categories of rain events during the 4 months of summer monsoon. Such results with details of changes in rain categories in different parts of India have important implications in agriculture sector in the country. [ABSTRACT FROM AUTHOR]

Climate variability is directly or indirectly affecting crop production and threatens the food security of livelihood. The Cauvery delta region (CDR) is the agricultural protective zone of Tamil Nadu state, the crop production in this region is vulnerable to climate change impacts. In this study, the future climate change impact of black gram yield has been assessed using the DSSAT-CROPGRO model in the CDR. The model was calibrated during the 2018 sowing period and validated during 2019 cultivation practices for determining the genetic coefficient of the black gram cultivar VBN6. The RMSE values of observed and simulated yield were 910 and 890 kg ha−1 respectively. RegCM4 model is used for the simulation of Vigna mungo yield under RCP 4.5 and 8.5 scenarios during the 1985–2015 (baseline), 2020–2039 (near-century), 2040–2069 (mid-century), and 2070–2099 (end-century). The results reveal that simulation of black gram yield change could be around 34%, 52%, and 25% during the near-century, mid-century, and end-century respectively for RCP 4.5 based on the baseline period. Adjusting the sowing date is evaluated as an adaptation option in future climate change scenarios, and results revealed that early sowing in the winter season could be the best suitable growing period for better yield in this region. [ABSTRACT FROM AUTHOR]

The present study assessed climate change vulnerability in agricultural sector of low-lying Sagar Island of Bay of Bengal. Vulnerability indices were estimated using spatially aggregated biophysical and socio-economic parameters by applying principal component analysis and equal weight method. The similarities and differences of outputs of these two methods were analysed across the island. From the integration of outputs and based on the severity of vulnerability, explicit vulnerable zones were demarcated spatially. Results revealed that life subsistence agriculture in 11.8% geographical area (2829 ha) of the island along the western coast falls under very high vulnerable zone (VHVZ VI of 84-99%) to climate change. Comparatively higher values of exposure (0.53 ± 0.26) and sensitivity (0.78 ± 0.14) subindices affirmed that the VHV zone is highly exposed to climate stressor with very low adaptive capacity (ADI= 0.24 ± 0.16) to combat vulnerability to climate change. Hence, food security for a population of >22 thousands comprising >3.7 thousand agrarian households are highly exposed to climate change. Another 17% area comprising 17.5% population covering 20% villages in north-western and eastern parts of the island also falls under high vulnerable (VI= 61%--77%) zone. Findings revealed large spatial heterogeneity in the degree of vulnerability across the island and thus, demands devising area specific planning (adaptation and mitigation strategies) to address the climate change impact implications both at macro and micro levels. [ABSTRACT FROM AUTHOR]

Production of the principal paddy crop in West Bengal state of India is vulnerable to climate change due to limited water resources and strong dependence on surface irrigation. Therefore, assessment of impact of temperature scenarios on crop evapotranspiration (ET) is essential for irrigation management in Kangsabati command (West Bengal). In the present study, impact of the projected temperatures on ET was studied under climate change scenarios. Further, the performance of the bias correction and spatial downscaling (BCSD) technique was compared with the two well-known downscaling techniques, namely, multiple linear regression (MLR) and Kernel regression (KR), for the projections of daily maximum and minimum air temperatures for four stations, namely, Purulia, Bankura, Jhargram, and Kharagpur. In National Centers for Environmental Prediction (NCEP) and General Circulation Model (GCM), 14 predictors were used in MLR and KR techniques, whereas maximum and minimum surface air temperature predictor of CanESM2 GCM was used in BCSD technique. The comparison results indicated that the performance of the BCSD technique was better than the MLR and KR techniques. Therefore, the BCSD technique was used to project the future temperatures of study locations with three Representative Concentration Pathway (RCP) scenarios for the period of 2006-2100. The warming tendencies of maximum and minimum temperatures over the Kangsabati command area were projected as 0.013 and 0.014 °C/year under RCP 2.6, 0.015 and 0.023 °C/year under RCP 4.5, and 0.056 and 0.061 °C/year under RCP 8.5 for 2011-2100 period, respectively. As a result, kharif (monsoon) crop evapotranspiration demand of Kangsabati reservoir command (project area) will increase by approximately 10, 8, and 18 % over historical demand under RCP 2.6, 4.5, and 8.5 scenarios, respectively. [ABSTRACT FROM AUTHOR]

This study has been undertaken to examine the occurrence of climate change in Tamil Nadu, the southernmost state of India and its impact on rainfall pattern which is a primary constraint for agricultural production. Among the five sample stations examined across the state, the minimum temperature has increased significantly in Coimbatore while the same has decreased significantly in Vellore whereas both minimum and maximum temperatures have increased significantly in Madurai since 1969 with climate change occurring between late 1980s and early 1990s. As a result, the south-west monsoon has been disturbed with August rainfall increasing with more dispersion while September rainfall decreasing with less dispersion. Thus, September, the peak rainfall month of south-west monsoon before climate change, has become the monsoon receding month after climate change. Though there has been no change in the trend of the north-east monsoon, the quantity of October and November rainfall has considerably increased with increased dispersion after climate change. On the whole, south-west monsoon has decreased with decreased dispersion while north-east monsoon has increased with increased dispersion. Consequently, the season window for south-west monsoon crops has shortened while the north-east monsoon crops are left to fend against flood risk during their initial stages. Further, the incoherence in warming, climate change and rainfall impact seen across the state necessitates devising different indigenous and institutional adaptation strategies for different regions to overcome the adverse impacts of climate change on agriculture. [ABSTRACT FROM AUTHOR]