This book is the result of a conversation among peers about climate change mitigation strategies in various disciplines within agriculture. We found the discussion intriguing and realized that such comprehensive literature was lacking. Thus, we conceptualized this book to bridge that gap and serve as a souvenir for our Ph.D. batch. Our primary goal was to gather information on the effects of climate change on agriculture and its mitigation strategies. The book provides detailed insights into how different disciplines tackle the threat of climate change. While this is an earnest attempt, we acknowledge that it is impossible to cover the entirety of such a vast subject in a single book. We welcome constructive criticism and suggestions from respected teachers, students, and all concerned individuals, as this will help us improve and refine the book in the future. We extend our deepest gratitude to the researchers who have dedicated their lives to understanding the effects of climate change. Their invaluable contributions form the foundation of our work. Additionally, we thank our peers for their collaboration, support, and insightful discussions that have greatly enriched this book.

Introduction The foundation of agricultural productivity lies in the realm of weather and climate, a reality unaltered by technological progress. The consequences of climate change on agriculture represent a worldwide apprehension, particularly significant for India. Around 54.6% of the Indian population is engaged in agriculture and allied activities, contributing to 17.4% of the country’s total gross value added. The agriculture sector is battling a multitude of challenges, such as increasing food demand, depletion of agricultural lands and water resources, and the devastating effects of climate change. It is high time that we acknowledge and address these issues to safeguard the future of our food systems and ensure food security for all. Climate change refers to the long-term variations in weather patterns and temperature over extended periods. Climate change occurs when earth’s climate system experiences variations in weather patterns that can last for decades or millions of years. These changes can arise naturally due to phenomena like volcanic eruptions or changes in solar activity. However, since the 1800s, human activities accelerate the natural pace of climate change, primarily due to the combustion of fossil fuels like coal, oil, and gas. These activities release greenhouse gases like carbon dioxide (CO2 ), methane (CH4 ), and nitrous oxide (N2 O) into the atmosphere, trapping heat and leading to a gradual increase in global temperatures. One of the most remarkable characteristics of climate change is the increase in temperature, which is widely referred to as global warming (Houghton, 2009). According to the report of Intergovernmental Panel for Climate Change, the release of greenhouse gases caused by human actions has contributed to around 1.1°C of warming since the period between1850-1900. The report also predicts that the global temperature will likely increase to 1.5°C or more in the next 20 years (IPCC, 2021).

Introduction Soil is a silent foundation and a dynamic part of Earth’s complex ecosystem. It sustains life, influences plant growth and is involved in various environmental processes. However, the balance of this vital resource is increasingly threatened by the pervasive effects of climate change, manifested by rising temperatures, changing rainfall patterns and changes in atmospheric conditions. As global temperatures rise and weather patterns change, the relationship between soil and climate poses transformative challenges with far-reaching consequences. This research addresses the complexity of this interaction and examines how climate change affects agriculture, soil health, composition and functionality. Soil health, a holistic concept that includes physical, chemical and biological aspects of soils, is closely linked to climate change. A notable consequence of climate change is the increasing frequency and intensity of extreme weather events such as droughts and floods. These events disrupt the delicate balance of soil ecosystems and lead to erosion, loss of topsoil and reduced fertility. Additionally, increased temperatures contribute to soil moisture depletion, reducing water availability for plants and microorganisms and further compromising soil health. A central issue at the interface between soil science and climate change is the role of soil as a carbon sink. Soils store large amounts of carbon in the form of organic material, thereby influencing the environment.

Introduction Climate plays a crucial role in shaping the agricultural landscape of a region, and the changing climatic conditions pose a significant threat to global food security. In developing countries in Asia and Africa, the primary challenges to realizing optimal crop yields are declining soil fertility, particularly soil organic carbon and drought. The unchecked emission of greenhouse gases is expected to lead to a considerable rise in the average global temperature by 6°C in the next century, primarily driven by activities such as fossil burning and urbanization. Over the past centuries, there has been a noticeable increase in the concentration of CO2 and CH4 , with up to a 35% expected rise in nitrous oxide due to the improper use of nitrogenous fertilizers. Climate models predict a substantial impact on agricultural productivity in the 21st century, with rising temperatures and more frequent extreme weather events (NASA, 2022). To maintain agricultural productivity, it is imperative to understand the effects of increasing temperatures, shifting precipitation patterns, and rising CO2 levels on soil health. It is noteworthy that climate is one of the key factors influencing soil formation, alongside four other factors. Temperature and precipitation directly affect soil formation by providing the necessary conditions for weathering and biomass production. The sum of active temperature and precipitation evaporation ratio are critical parameters that determine energy consumption for soil formation, water balances in soil, organic-mineral interactions, and the transformation processes within the soil. However, human activities such as population growth, deforestation, disruption of marine ecosystems, and the greenhouse effect contribute to climate change, leading to denudation, depletion of soil organic matter, destruction of soil structure, erosion, and desertification, ultimately causing a decline in soil health and environmental degradation (IMD, 2021). Despite being a gradual process, climate change, characterized by small, long-term changes in temperature and precipitation, significantly influences various soil processes, particularly those related to soil fertility. The anticipated effects of climate change on soils primarily involve alterations in soil moisture conditions, increased soil temperature, and elevated CO2 levels. Understanding the consequences of climate change on soil health is crucial, as it has far-reaching impacts on agriculture, biodiversity, carbon cycling, and ecosystem resilience in the face of an evolving climate (Nunez et al., 2019).

Introduction Climate change has significant adverse implications on the physiological processes and metabolic machinery of plants, potentially affecting growth, development, and overall crop productivity. The rapid increase in global population exacerbates the threat to global food security, which is further impacted by changing climate conditions. The Intergovernmental Panel on Climate Change (IPCC) estimates that between 1850 and 1900 and 2011 and 2020, the global mean land surface air temperature increased by 1.6 °C. Predictions by the United Nations indicate that the global human population could reach 8.5 billion by 2023 and 9.7 billion by 2050, up from the current 8 billion. The National Centers for Environmental Information (NCEI) reported that 2022 was 0.86°C warmer than the average of the 20th century, making it the 6th warmest year on record. These data suggest an increased probability of unpredictable climate changes and harsh growing conditions, manifesting as various abiotic stresses on major cultivable lands. Climate change impacts CO2 concentration, temperature, precipitation, pollutants, and nutrient availability and uptake, leading to drought, salinity, irregular rainfall, f looding, high temperatures, and nutrient deficiencies in staple food crops, thereby threatening global food security. This review focuses on the effect of elevated CO2 and temperature on fundamental plant metabolic processes such as photosynthesis, respiration, transpiration, and nitrogen metabolism.

Introduction The world’s food and nutritional security are under serious threat from climate change. Climate changes have significant effects on agriculture by affecting insect pests, their natural enemies, and pollinators as illustrated in Fig 1 (Eigenbrode and Adhikari, 2023). According to Benedict (2003), 13.6% of annual crop loss worldwide is attributed to insect pest attack. Crops, crop pests, natural enemies and pollinators are directly and indirectly impacted by erratic climate. The continuous and anticipated alterations in these insects vary across species, systems, and geographical areas, impeding the development of strong generalizations and forecasts. Moreover, the implementation of “climate-smart” agricultural methods, may have additional effects on ideal management of these insects. Direct effects on insect pests Temperature: The most reliable, well-researched, and easily modelled component of climate change is warming. Warming affects physiology, phenology, dispersal, reproduction, development, and survival of insect pests (Bale et al., 2002) as illustrated in Fig 2 (Skendži? et al., 2021). It can be inferred that increased herbivory would be associated with rising temperatures in many cases. High temperature and high humidity are key reasons for whitefly population increase (Pathania et al., 2020). Warming can alter the number of insect generations in Helicoverpa armigera (Lepidoptera: Noctuidae) in China (Huang and Hao, 2020).

Introduction The “plant disease triangle” is a fundamental concept in plant pathology that illustrates the interaction between three essential components necessary for the development of a plant disease. Firstly, the host plant which refers to the plant species or cultivar that is susceptible to the pathogen. Host plants provide the necessary environment and resources for the pathogen to establish, grow, and reproduce. Secondly, the pathogen which is any organism (such as fungi, bacteria, viruses, nematodes, or other microorganisms) that can cause disease in plants. Pathogens can infect host plants through various means, including direct contact, airborne spores, soil-borne organisms, or vectors such as insects. And thirdly, the environment which encompasses all external factors that influence the interaction between the host plant and the pathogen. This includes abiotic factors such as temperature, humidity, soil moisture, light, and nutrient availability, as well as biotic factors such as the presence of other organisms (competitors, predators, symbionts) that may affect disease development. The plant disease triangle illustrates that the occurrence of a disease requires the presence and interaction of all three components: a susceptible host, a virulent pathogen, and a conducive environment. If any of these components is missing or unfavourable, disease development may be inhibited or prevented. Any change in ecosystem can affect plant diseases, because plant disease is the result of interaction between a susceptible host, virulent pathogen and favourable environment. If any of the three factors are altered, the progress of any one disease can change. Although interactions among the three factors must be matched, weather is an important variable due to its dynamic behaviour.

Introduction Rising temperature, decreasing precipitation, increased frequency in drought and flooding, etc. is making us realize climate change is not some cooked up story. Still there are people who believes climate change is not real. By definition, Climate change is a long-term shift in global or regional climate patterns. This will affect the life of people in many forms: health, food, water, etc. (Table 1). Agriculture is a highly vulnerable field to such weather and climate changes, they can have significant direct and indirect impacts on farm productivity and profitability. Climate change will have adverse effect on crop physiology, growth and chemistry and thus it will cause negative impact on agricultural production. Because of the variation in climate, moisture availability may change, which limits vegetation activity/plant growth, increase in drought/ heat/flooding will the crop growth and yield. Elevated CO2 does not have a profound effect on C4 plants. On the contrary, tissue nitrogen concentrations are higher for C3 species under increased CO2 . Intergovernmental Panel on Climate Change (IPCC) estimates that climate change and elevated CO2 is expected to increase competitiveness of invasive weed. IPCC also estimates that with 1°C rise in global temperature, 5 to 10 per cent yield reduction of major food and cash crops (Pachauri et al., 2014).

Introduction Climate change is a deadliest hazard to life on Earth. Global temperature is rising due to greenhouse gas emissions from the usage of fossil fuels, this result in widespread agricultural and fisheries failure, the extinction of hundreds of thousands of species, and whole towns becoming uninhabitable (Lindwall, 2022). Rising global temperatures are severely killing humans and trees, forcing half of all species to move, worsening water-borne and respiratory ailments in people, and jeopardising millions’ food and water security (Isaacs-Thomas, 2022). Addressing these concerns necessitates a worldwide collaboration to minimise greenhouse gas emissions and promote sustainable behaviours. Climate change affects agriculture production, lowers crop nutritional value, and increases the frequency of extreme weather events. These interruptions jeopardise food production, availability, and access, especially in vulnerable countries. Microbes play an important role in soil health, nitrogen cycling, and ecosystem stability. They impact a variety of soil activities, such as organic matter breakdown, nutrient mobilisation, and plant growth stimulation. However, climate change poses a substantial danger to microbial communities, possibly changing their activities and altering ecosystem dynamics (Wang et al., 2022). Transitioning to a low-carbon economy requires a global effort. Mitigation strategies include enhancing energy efficiency, adopting renewable energy sources, electrifying industrial processes, implementing efficient transportation systems, and introducing carbon taxes or emissions markets.

Introduction Climate change is widely acknowledged as the most significant contemporary challenge facing humanity. According to a recent report from the Intergovernmental Panel on Climate Change (IPCC, 2022), the situation has deteriorated further, with 3.3 billion people worldwide highly susceptible to climate change. Current unsustainable development practices are escalating the exposure of ecosystems and populations to climate-related risks. Human activities and their impact on the climate and environment are leading to unprecedented extinctions of animals and plants, resulting in a loss of biodiversity and posing a threat to life on Earth. The diversity of microorganisms is fundamental to maintaining a healthy global ecosystem, as the microbial world serves as the life support system of the biosphere. Although the influence of human activities on microorganisms is less conspicuous and less well understood, a significant concern is that changes in microbial biodiversity and functions will impact the resilience of other organisms, affecting their ability to adapt to climate change. Microorganisms play crucial roles in carbon and nutrient cycling, as well as in the health of animals (including humans), plants, agriculture, and the global food web. Microorganisms inhabit all environments on Earth occupied by larger organisms and are the exclusive life forms in certain environments such as the deep subsurface and extreme habitats. Dating back to the origin of life on Earth at least 3.8 billion years ago, microorganisms are likely to persist well beyond any future extinction events. Despite their vital role in regulating climate change, microorganisms are seldom the focal point of climate change studies and are typically overlooked in policy development. The challenge lies in understanding their intricate role in the ecosystem due to their vast diversity and varied responses to environmental changes.

Introduction Climate change may advance more rapidly than anticipated, introducing novel environmental conditions for cultivating horticultural crops. The rise in atmospheric CO2 levels from non-renewable energy sources combustion drives global average temperatures, altering weather patterns worldwide with regional variations (Stocker et al., 2013). Currently, certain regions are already experiencing the effects of extreme weather events such as heat waves or frost, while prolonged droughts pose a growing threat to global food security elsewhere. Climate changes may yield both positive and negative outcomes, but they will undoubtedly alter production conditions and product quality (Kaufmann and Blanke, 2017). Elevated temperatures can enhance the ability of air to hold water vapor, leading to increased water demand. This process can elevate evapotranspiration rates, potentially depleting soil water reserves and causing water stress in plants during dry periods. Fruit production is particularly vulnerable to water stress, especially in regions where trees lack irrigation. Numerous studies indicate that water stress diminishes crop yields and hastens fruit ripening (Henson, 2008).  

Introduction Agriculture is the backbone of every country. It largely depends on climate and its changes. Over the last few years climate change has affected crops, cropping systems, patterns and the ecosystem hugely. Climate change is caused by greenhouse gases in the atmosphere, which results in global warming (Aydinalp and Cresser, 2008). The rising temperature, melting of glaciers, loss in vegetation cover, frequent occurrences of drought and floods are some of the issues that have raised concern among the environmentalists. The change in temperature and precipitation patterns alters the traditional growing seasons. Climate change is expected to influence crop and livestock production, hydrologic balances, input supplies and other components of agricultural systems (Adams et. al., 1998). Vulnerability of climate change depends on physical, biological and socio-economic characteristics. Low income populations dependent on isolated agricultural systems are particularly vulnerable to hunger and severe hardship. These populations are already barely food-sufficient, even the slightest decline in yields could be very harmful in these areas. The most negative effects are foreseen in dry land areas at lower latitudes and in arid and semi-arid areas, especially for those reliant on rain fed, non-irrigated agriculture (Aydinalp and Cresser, 2008). The rise in temperature cause stress in crops and reduce yields and productivity. Crops that are sensitive to temperature during the growth stages are affected a lot. A shift in growing season is being seen due change in temperature. Irregular and altered patterns of rainfall are severely affecting the crops and water supplies for livestock, which in turn has increased the occurrence of floods and drought, causing soil erosion, disrupting harvesting schedules. Occurrence of new pests and diseases are seen in the places having warmer temperature. Altered temperature has altered the life cycle of pests and intensity of infestations. Rising of sea water level and increased evaporation leads to intrusion of salt water into fresh water making irrigation water more saline harmful to crops. Livestock are sensitive to heat stresses which in turn reduce livestock productivity and increase mortality rates.