Effects of Climate Change on Crop Production and its Mitigation

Climate change has been the topic of conversation for decades, with activists like Greta Thunberg and David Attenborough being preceded by those that are destroying art in order to bring about action on climate change. While many believe that these new forms of protest are counter-productive to the cause, these attempts do force one to think through the never ending list of impacts climate change has on our daily lives; food security being at the forefront of the said risk. 

Just Stop Oil climate protesters after throwing soup on Vincent Van Gogh's Sunflowers at the National Gallery in London. Photo: Just Stop Oil / Handout/Anadolu Agency via Getty Images

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Climate change is defined as the changes in the average conditions such as rainfall and temperature in a region over an extended period of time. Some of these changes include: warming temperatures and variations in precipitation, as well as the consequent effects of Earth’s warming, i.e. rising sea levels, melting mountain glaciers and the loss of precious plant and animal species such as the Blind Indus dolphin in Pakistan. 

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These environmental changes have the potential to impact the location, timing and the subsequent productivity of crops and livestock. The consequences for the agriculture sector are integral because the agricultural sector in Pakistan contributes about around 20 percent of gross domestic product, accounts for half of the employed labor force, and is the largest source of foreign exchange earnings according to the Pakistan Bureau of Statistics.

Photo: Agencies

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Effect of Climate Change On Crop Production:

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Climate change poses a major challenge to agriculture systems owing to the acute interdependence of the two. According to a consensus of the Intergovernmental Panel for Climate Change (IPCC), global mean surface air temperature will predictably increase by 0.4 to 2.6°C in the second half of this century. While many would assume that these gradual increases in temperature as well as carbon dioxide would result in higher crop yield - that is unfortunately not the case. This is because these changes will restrict any possible yield increases by bringing along extreme climate events like the recent Pakistan floods or the all encompassing heat waves across Europe in the summer of 2022. 

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These acute disruptions in environmental conditions have a knock on effect on yield especially during crop flowering. The following figure summarizes average crop production showing decreases in yield during the 21st century owing to climatic changes. 

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Summary of projected changes in crop yields, due to climate change over the 21st century. The figure includes projections for different emission scenarios, for tropical and temperate regions, and for adaptation and no-adaptation cases combined.

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Rising temperatures result in heat waves i.e. periods of extremely high temperature, which  are likely to become more frequent in the future. Heat waves impact crop growth and development at various levels like soil moisture uptake, root and shoot growth, photosynthesis, respiration, plant water uptake and final yield. These intense temperatures increase the contenders for soil moisture by hastening evaporation and transpiration, leaving little to no moisture for uptake by plants. More importantly, these record breaking temperatures are especially detrimental when plants are flowering as the disruption of this single critical stage leaves minimal seeds for future sowing.  

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In the context of Pakistan, a 2020 report of Global Climate Risk Index asserts that Pakistan is the fifth among the countries most vulnerable to global warming and climate change. Many studies suggested that temperature increases will shift Pakistan’s cropping seasons and could potentially permanently eliminate the viability of growing some

cash crops like wheat, maize, cotton, rice, and sugarcane.

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Along with these frequent periods of intense heat, there is an increase in drought incidences which are likely to exacerbate existing issues around food security. However, projected changes in climate are not limited to the rising mercury and heat waves only - significant variations in rainfall patterns are also occurring where some regions will be suffering due to droughts and others will be washed along due to torrential rains and heavy floods. 

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Climate change is currently the biggest unmitigated external risk to the water sector in Pakistan. The phenomenon is not expected to significantly alter average water availability for times to come, but what it will do is produce great variations in water availability, multiplying the severity of floods and droughts - as was seen during the environmental strain laden year of 2022.

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Pakistan was suffering from a water shortage throughout the early summer of 2022: in May the Sindh Chamber of Agriculture demanded that the province be declared drought-hit because water shortage had left agricultural land barren, so much so that when winter crops were being sown, there was 70 percent water scarcity in the province - shrinking the area that could be used for growing crops. However, a few weeks later the said province was under more than 8 feet of flood water. 

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Sindh: Changes in yield and farmed area of four major crops.

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What this unreliability of water access and availability pendulating between two very serious extremes does is make the lives of Pakistani farmers even more difficult. Agriculture in Pakistan is heavily dependent upon the Indus Basin and the rainwater that flows through it. During the first wet season of Pakistan i.e. February till March, water scarcity was immense to an extent where dams such as The Tarbela Dam reached dead level on Feb 22, while the Mangla Dam held less than 1 percent of its total capacity. Consequently, the Kharif season had to begin with a 40 percent water shortage, where farmers had no water for the last irrigation of wheat and similar conditions prevailed at the start of cotton season i.e. there was no water for soil preparation and for 1st irrigation of the crucial crop. 

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A worker loads raw cotton onto a truck in Sindh’s Sanghar district in July 2022. So far, 45% of the monsoon season’s cotton crop has been lost in the southeastern province of Pakistan.

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The situation was at the opposite extreme for the second wet season for Pakistan. The intense heat during the summer resulted in torrential rains and deluges leading to country wide losses of crops covering 2.7 million hectares of land, that is how big Sweden in its entirety is! The saddest part is, Pakistan is not equipped structurally and/or non structurally to control and save this water for future uses - Pakistan and its people have already paid such a hefty price for.

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What Can be Done to Mitigate:

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The problems mentioned above are not alien to Pakistan as the 2010 floods are a painful reminder of destruction and lessons that were not learnt. However, we still have time to adapt and mitigate the rapidly appearing challenges in the face of climate change via climate smart agriculture and its 3 principles that dictate the following: sustainably increasing productivity and income, increasing adaptation, and reducing greenhouse gas emissions.

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The adoption of heat and drought resistant varieties (climate resilient agriculture) can help make our food sources more dependable and the yield predictable, especially when the environment is anything but that. Furthermore, the utilization of cover crops offers agricultural producers a natural and relatively inexpensive climate solution via the crop’s ability to fix atmospheric carbon dioxide and nitrogen into soil. This ability of cover crops such as mustard, alfalfa, rye, clovers, buckwheat etc. helps prevent the leaching of nitrogen into ground and river water which would otherwise cause eutrophication and subsequent habitat destruction. This practice also saves capital on inputs like water and fertilizer making crops more resilient to the changing climate. Cover crops and their fixation property leads to healthier soil which is better equipped with water infiltration and water holding capacity and is less susceptible to erosion from wind and water.

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Similarly, Genetically modified crops can help reduce agricultural greenhouse gas emissions. Genetically modified yield gains also mitigate land-use change and related emissions. Some agronomic measures that can be adopted immediately and independently by farmers include: not burning rice and/or wheat straw after harvesting, and instead layering it over soil as a mulching to prevent the loss of soil moisture. These wheat and rice

straws also increase the soil fertility.

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Genetically Modified maize varieties.

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Structural modifications in the form of small dams and barrages are essential to regulate water supply to farmlands as well as to help reduce the instances of floods. For more sustainable water use, modern techniques of irrigation like sprinkler irrigation, rain gun, drip irrigation etc. should be adopted in place of conventional flooding techniques, to be able to better conserve water and soil health.  

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Furthermore, deep ploughing should be done before monsoon in barani areas to conserve water for future consumption. To minimize the negative consequences of high temperatures; the use of windbreakers, mulching, proper nutrition supply and timely irrigation will be most appropriate. Conversely, at lower temperatures frost injury is the major source of crop and orchard losses where the appointment of  wind breakers and light irrigation will be particularly beneficial. 

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