Impact of climate change on Punjab Agriculture

Climate change is a change in the state of the climate that can be identified (e.g., using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be related with natural processes or external forcings (as for example volcanic eruptions, modulation of the solar cycles, etc.) or with persistent anthropogenic changes in land use or composition of the atmosphere. The impact of climate change will pose one of the greatest challenges to humanities in the 21st century. The increase in global mean temperature is strictly linked with human activities emitting high quantities of greenhouse gasses in the atmosphere. Agriculture will be the sector most affected by climate change. Ensuring food security in a context where temperature will rise and precipitation patterns will be shifted is a key challenge for the future. This is particularly true in countries such as India, where agriculture still plays a crucial role in ensuring access to food to many people. In India the annual mean land surface air temperature in 2018 was +0.41°C higher than the 1981-2010 average, making 2018 the sixth warmest year on record since 1901. 2019 was the seventh warmest year on record, with annual mean surface air temperature +0.36°C higher than the 1981-2010 period average. In order, the five warmest years on record were 2016 (+0.71°C), 2009 (+0.54°C), 2017, (+0.54°C), 2010, (+0.54°C), and 2015 (+0.42°C). It should be noted that eleven of the fifteen warmest years have occurred in the last fifteen years (2005-2019) according to the Third biennial report to the United Nations Framework Convention on Climate change. During the National Innovations in Climate Resilient Agriculture program, the effects of climate change on Indian agriculture were investigated. In India, it is foreseen that irrigated rice yields will increase by 7% in 2050 and 10% in 2080 scenarios, while rainfed rice yields will decrease somewhat (2.5% in each scenario). Moreover, maize yields are predicted to drop by 18–23% and wheat yields by 6-25% in 2100. Thus, investigating the effect of temperature increase on crop productivity is the first step to plan for future adaptation strategies. This thesis focuses its attention on the impact of temperature increase on wheat cultivation in Punjab, more specifically in the top three wheat producing counties of Punjab (Barnala, Faridkot and Sangrur) since Punjab is the major wheat producer of India. The wheat yield reduction with respect to the 2009-2018 period in the near, medium and long-term and in three Shared Socioeconomic Pathways (SSPs) of the IPCC (Intergovernmental Panel on Climate Change) was evaluated. The three SSPs are SSP1 (focused more on human well-being than on economic growth), SSP2 (in which global population growth is moderate and environmental systems are facing a certain degradation) and SSP5 (the worst scenario, in which the social and economic development is based on an intensified exploitation of fossil fuel resources with a high percentage of coal and an energy-intensive lifestyle worldwide). The APSIM (Agricultural Production System Simulator) crop model was used to simulate future yields in the three SSPs and in near, medium and long-term. ASPIM was initialized with weather data (daily rainfall, solar radiation, maximum and minimum temperature) retrieved from the ERA5 reanalysis dataset, soil texture information derived from the Soil Grids dataset and crop management practices (sowing date, sowing density, etc.) suggested to farmers by the Ministry of Agriculture of Punjab. The weather and soil texture data were processed through the use of geographic information systems (GIS) and a software to manage gridded data in the NetCDF format. Once the model was initialized, it was calibrated and validated thanks to the use of observed wheat yield data retrieved from the Government of Punjab.