Climate change may be amplified, including heat (since urban areas are usually warmer than their surroundings), flooding from heavy precipitation events and sea level rise in coastal cities
(IPCC, 2021). It causes increase in temperature, variation in rainfall pattern, sea level rise, extreme weather activity, generation of floods and droughts etc
(Shetty et al., 2013; Pathak et al., 2012). Climate change is not harmful for all place or territory and the problem that arise of extreme events are not predict easily
(FAO, 2001). More variability in rainfall and unpredictable high temperature spell will consequently reduce the crops productivity. The anthropogenic activities are responsible for an increase in gases,
viz. carbon dioxide (CO
2), methane (CH
4), nitrous oxide (N
2O) and chlorofluorocarbons (CFCs) popularly known as the “greenhouse gases”. Drastically increase in concentration of CO
2 in 2019 was 409.8 ppm wit a range of uncertainty of plus or minus 0.1 ppm (
NOAA Climate.govt, 2020). Climate change highly impact on agriculture, horticulture, environment and health all over the world. Soil organic matter decomposition, nutrient recycling, nutrient availability and water availability stresses impact on growth of plant due to environmental stresses. It is predicted that by 2080 the cereal production could be reduced by 2%-4%, meanwhile the price will increase by 13%-45%, and about 36%-50% of the population will be affected by hunger
(FAO, 2009). In fact, the average temperature of the planet has increased by 0.8° Celsius (33.4° Fahrenheit) compared to the end of the 19
th century. Each of the last three decades has been warmer than all previous decades since the beginning of the statistical surveys in 1850. At the pace of current CO
2 emissions, scientists expect an increase of between 1.5° and 5.3°C (34.7° to 41.5°F) in average temperature by 2100. If no action is taken, it would have harmful consequences to humanity and the biosphere. Agriculture is one of the basic activity by which humans live and survive on the earth. Assessment of the impact of climate change on agriculture is a vital task. In both developed and developing countries, the influence of climate on crops despite irrigation, improved plant and animal hybrids and the growing use of chemical fertilizers. Anthropogenic warming has resulted in shifts of climate zones, primarily as an increase in dry climates and decrease of polar climates (high confidence). Ongoing warming is projected to result in new, hot climates in tropical regions and to shift climate zones poleward in the mid- to high latitudes and upward in regions of higher elevation (high confidence). Globally, greening trends (trends of increased photosynthetic activity in vegetation) have increased over the last 2-3 decades by 22-33%, particularly over China, India, many parts of Europe, central North America, southeast Brazil and southeast Australia (high confidence). Climate change impact the ecosystem in all over the world as showed in Fig 2. The frequency and intensity of some extreme weather and climate events have increased as a consequence of global warming and will continue to increase under medium and high emission scenarios (high confidence). The total net land-atmosphere flux of CO
2 on both managed and unmanaged lands very likely provided a global net removal from 2007 to 2016 according to models (-6.0±3.7 GtCO2 yr
-1, likely range). These regions differ significantly in their biophysical characteristics of climate and soil, and in the vulnerability of their agricultural systems and people to climate change.
In Fig 1 shows that change in surface air temperature over land has risen considerably more than global mean surface (land and ocean) since pre-industrial period (1850-1900). From 1850-1900 to 2006-2015 mean land surface air temperature has increased by 1.53°C (very likely range from 1.38°C to 1.68°C) while GMST increased by 0.87°C (likely range from 0.75°C to 0.99°C).
Climate change impact on soil
Climate change impact is continuously watching on the weather phenomena by meteorologists and climatologists around the world. And the impact is huge: more droughts and heatwaves, more precipitations, more natural disasters like floods, hurricanes, storms and wildfires, frost-free season,
etc. Climate impacts on agriculture lies the biophysical processes are highly dependent on climate variables such as radiation, temperature, and moisture that vary regionally. For example, rates of plant photosynthesis depend on the amount of photosynthetically active radiation and levels of atmospheric carbon dioxide (CO
2).
Climate change will also have an impact on the soil. Higher air temperatures will cause higher soil temperatures, which should generally increase solution chemical reaction rates and diffusion-controlled reactions as showed in Fig 3. Furthermore, higher temperatures will accelerate the decay of soil organic matter, resulting in release of CO
2 to the atmosphere and decrease in carbon/nitrogen ratios
(Buol et al., 1990). The largest producer of GHG emissions are China and United States (accounting for around 42%) (http://cdiac.ornl.gov/trends/emis/tre_coun.html) and the third is India where agriculture is responsible for 18% of total national emissions. Soil organic matter decomposition is temperature sensitive and loss of SOC due to changes in C and N dynamics, altered nutrient bioavailability and reduction in soil biodiversity as result of climate change. This would result in poor soil health and in turn soil fertility. Few studies on the effect of top soil warming on SOC stocks for example in grassland, grazed pasture and forest
(Ross et al., 2013; Dawes et al., 2013). Kirschbaum, (1995) reported that loss of SOC will be 10% due to increase in temperature as an annual mean temperature of 58°C.
Zhou et al., (2018) revealed that old SOC decomposition is more sensitive to temperature than younger components.
Mitran et al., (2018) reported that the total carbon is stored in large amounts in Alfisols (0.49 Pg C) followed by Inceptisols (0.35 Pg C) and Entisols (0.27 Pg C) in the southern states of India.
Guo et al., (2019) showed that soil structure is strongly influenced by the OC status in soil, so, any practice that leads to decline in OC will decrease in soil aggregate stability, infiltration rate and increase in susceptibility to compaction, runoff. In the ultisols of south-eastern China, with farmyard manure. Climate change causes changes in the intensity and volume of rainfall as so increase the erosive power to detach and carry soil particles and the prediction of average global soil erosion to increase by 9% for 2090
(Yang et al., 2003).
Impact of climate change on crops
Parry et al., (1988a) report on integrated agricultural sector studies in high-latitude regions in Canada, Iceland, Finland, USSR and Japan, concluding that warmer temperatures may aid crop production by lengthening the growing season, but that potential for higher evapotranspiration and drought conditions may be detrimental.
Parry et al., (1988b) studies the impact of climate changes on agriculture in Kenya, Brazil, Ecuador, India, and Australia.Tthe impacts of past climatic variations, rather than projections of future climate, to provide insights into the sensitivity of agriculture to climate change.
Liverman and OBrien (1991) have described how global warming may affect Mexican agriculture, using GCM output to project declines in moisture availability and maize yields at several sites in Mexico.
Kumar and Parikh (2001) showed that rice and wheat yield reduction, which in turn would adversely impact on production by 2060 and may affect the food security of more than one billion people in India, projected on large-scale changes in climate. Different study was conducted in yield reduction by drought in different growth stages in field crops as shown in Table 1,2.
Wheat, barley, sorghum, arhar and maize food grain crops get negatively affected due climate sensitivity or the fluctuations in temperature and rainfall pattern and thus it may threaten food security in India
(Kar and Kar, 2008;
Ranuzziand Srivastava, 2012).
Singh, (2012) showed that climatic change have negatively affect on cash crop production and empirical result showed that increments in maximum temperature have a negative impact on non food grain (commercial) and statistically significant on sugarcane, cotton and sesamum crop. Any variation in minimum temperature from normal has a negative and statistically significant impact on and linseed productivity and any fluctuation in rainfall from average has negatively affected the sugarcane productivity.
Kumar et al., (2011) mentioned that decline in the irrigated area for maize, wheat, and mustard in northeastern and coastal regions and for rice, sorghum and maize in Western Ghats of India may cause loss of production due to climate change.
Hundal and Kaur (2007) concluded that rice and wheat productivity declining upto 3% and 10% due to increase in minimum temperature up to 1.0°C to 3.0°C above normal respectively, in Punjab.
Kaul and Ram (2009) found that excessive rains and extreme variation in temperature have adversely affected the productivity of Jowar crop, thereby this has affected the incomes as well as food security of farming families in Karnataka (India).
Geethalakshmi et al., (2011) concluded that rice productivity has declined up to 41% with a 40°C increase in temperature in Tamil Nadu.
Saseendran et al., (2000) analyzed the projected result showed that increment in temperature up to 50°C could lead to a continuous decline in the yield of rice and every 10°C increment in temperature will lead up to 6% decline in yield for duration 1980-2049 in Kerala (India).
Srivastava et al., (2010) found that climate change will reduce monsoon sorghum productivity up to 14% in the central zone and up to 2% in the south central zone by 2020. Climate change has shifted and shortened crop the ration in major crops the ice and sugarcane, and it has significantly affected cane productivity in Uttar Pradesh and Uttarakhand
(Boopen and Vinesh, 2011). The impact of rainfall is not significant for sugarcane crop in Andhra Pradesh
(Ramulu, 1996). In India, projected surface warming and shift in rainfall may decrease crop yields by 30% by the mid of 21
st century; due to this reason, there may be a reduction in arable land resulting into pressures on agriculture production
(Kapur et al., 2009).
Climate change impact on horticulture crop
Climate change is directly related to change in weather pattern and arises of abiotic stress. Its directly impact on plant architecture and growth. Abiotic stress is the primary causes of low production for most of the fruit crops and vegetables on all over the world as shown in Table 3.
High temperature causes an array of morpho-anatomical changes in plants which affect on seed germination, growth, flower shedding, pollen viability, fruit setting, fruit size, weight and quality
etc. heat stress on fruit crops causes physiological disorders and their associated problems. In many crops like sweet corn, lettuce, carrot, cucurbits, tomato etc. is poor pollination under low humidity and high temperature with the reduction of the number of pollination insect species
(Deuter, 2008). In tomato, pollen germination is affected by temperatures above 27°C or causes reduced fruit set, smaller size and lower quality fruits
(Stevens, 1978) Floral abortion will occur in capsicum when temperatures exceed 30°C
(Erickson and Markhart, 2002). In beans, high temperature delays flowering because they enhance the short day photoperiod
(Davis, 1997). Drought-stress causes an increase in solute concentration in the environment (soil), leading to an osmotic flow of water out of plant cells. This leads to an increase in the solute concentration in plant cells, thereby lowering the water potential and disrupting membranes and cell processes such as photosynthesis. Water-stress condition affects the plants in terms of narrow leaf orientation, lesser germination, delayed maturity, small and delayed flowering, decline in chlorophyll content, reduced rate of transpiration, less uptake of nutrients, and severe reduction in yield
(Bhardwaj, 2012). Under saline condition, pea shows poor seed germination
(Kumar et al., 2012). In coconut, arecanut and cocoa, increased CO
2 led to higher biomass production and total dry matter content
(Singh et al., 2010).
High temperature has big influence on fruit growth, a large number of furit crops production timing will change including mango, citrus, banana and guava crops will develop more rapidly and mature earlier due to rise in temperature
(Malhotra, 2017). High temperature with moisture deficit causes cracking and sun burning in apple
(Rai et al., 2005) and increase in temperature during maturity stage will cause cracking in litchi
(Kumar and Kumar, 2007). Low temperature (4-11°C), high humidity (80%) and cloudy weather during the month of January caused delayed panicle emergence in mango. Strong wind and cyclone during mango fruit season reduced yield by shedding of fruits and also affect the fruit size and quality
(Chadha, 2015).
Adaptation and mitigation strategies
Adaptations to climate change exist at the various levels of agricultural organization. At farm-level adaptations include changes in planting and harvest dates, tillage and rotation practices, substitution of crop varieties or species in contrast to the changing climate regime, increased fertilizer or pesticide applications and improved irrigation and drainage systems. Governments can facilitate policy to adaptations climate change through water development projects, agricultural extension activities, incentives, subsidies, regulations, and provision of insurance.