Food systems have been changing since the beginnings of human history, during most of which humans hunted and gathered for food nomadically. Today’s food systems are by contrast complex and globally interconnected, as food products may be grown in the United States, processed in China, and then distributed in South America. Throughout history, parts of the world have often experienced continuous periods of hunger, which have often come about because of war, plague, or hostile weather. The past 70 years’ technological advancements counteract this, and increasing global cooperation has begun to suggest the possibility for nations to significantly reduce hunger throughout the world. Despite such progress, the United Nations World Food Programme reports that over 800 million people lack the food to support a healthy, active life.
Efforts to end hunger improve each year, but climate change stands as an obstacle to this goal which may worsen global hunger. Changes in the earth’s climate, temperature, and weather patterns have been occurring for millions of years. World climate has undergone changes which disrupt these more normal, epochal changes. These changes consequently abet trends that will in turn cause scenarios threatening to human life and behavior.
One of these threats is to food security. Four major parts comprise the food system: production, stability, access, and utilization. Agricultural determinants of food security are broadly defined as all effects of climate change on food production and its process. These effects include increased temperatures and frequency of storms and severe weather. I believe that these effects and their associated case studies afford understanding of food security within the context of their impacts on crops and livestock, thus allowing the public to understand climate change directly from the perspectives of agricultural industries.
Climate Change Impacts on Agriculture Production and Crop Stability
Agriculture and its related industries depend immensely on climate. Crop production and livestock are the largest global food industries and are highly sensitive to climactic shifts. Increases in temperature, changes in precipitation patterns, and changes in storm frequency and severity often significantly affect food production. Though effects vary across regions, climate change presents troubles and uncertainty to countries across the globe. Climate scientists anticipate that climate change will cause short-run increases in agricultural productivity in some high-income, high-latitude countries, but these scientists expect the effects in equatorial countries to be devastating. Low-income countries primarily in sub-Saharan Africa and Latin America already suffer from poor agricultural productivity and food insecurity, conditions which climate change is expected to exacerbate.
Climate change is expected to impact crop production and growth through four primary, interrelated mechanisms: increasing temperature; frequenter extreme weather events; distribution changes of arable land; and increasing carbon dioxide levels. Each mechanism’s impact varies based on its severity, region, and affected crops’ adaptations.
Temperature plays a significant role in agricultural crop development and preservation. Biologically, temperature profoundly affect plant physiology, such as high temperatures altering plant cells to lessen crop yields. High temperatures also cause severer weather and rising sea levels, both of which are explicit risks to farming and other agricultural industries throughout the world. Because temperature determines plant growth cycles, seasonal variations and temperature extremes pose dangers to crop production. Crops only tolerate specific temperatures which, if exceeded, result in lessened crop productivity.i Many rain-fed crops in Africa and South America for example currently near their temperature tolerances, which means that even a modest temperature increase will lead to drastic reductions in crop yields. This is because temperature and heat stress directly influence on plant composition. Likewise, temperature shifts disrupt seasonal biomass growth, because critical windows in crop development, such as pollination, are obstructed or delayed.ii Increases in temperature also speed up crop maturation, shortening the seeding and harvesting period. Consequently, this increases the rate of senescence, which is the aging and deterioration of crops. Stable temperatures are important to perennial plants, which flower and mature over Spring and Summer, then die every Autumn and Winter to return the following Spring from their rootstocks.iii Perennial plants are vulnerable to inauspicious climate changes because they require a certain number of frost days to maintain optimum yields and quality.iv Climate change threatens to damage perennial plant production because it is expected to lengthen warm seasons and shorten the cold.
Climate change is expected to increase the frequency of severe weather patterns, notably droughts and floods. Drought can destroy entire yields or can result in drastically reduced production, even for farmers who irrigate their fields. Similarly, flooding and excess precipitation damage farmland. According to a report from DuPont Pioneer, the magnitude of damage depends on several factors: the crop, its growth stage, the duration of flooding, and the temperature during flooding. Aside from rice, most crops are largely intolerant to flooding. Potatoes, dry beans, and wheat for example can endure submerged soils no longer than one to two days.v Other crops, such as corn and soybeans, may survive four days in submerged soils.vi Damage to submerged crops occurs because the soil quickly becomes deficient of oxygen, an element necessary for plants’ growth and development. Especially during the reproductive stages, such as during pollination, crops are more easily damaged by flooding than during the vegetative and flowering stages.vii
Changes in Access to Arable Land
Climate change is expected to increase the availability of arable farmland in high-latitude regions, such as in northeastern Europe and Russia, but reduce it in equatorial regions, particularly in sub-Saharan Africa and Brazil. By the end of the century, low-lying regions and islands are expected to lose a significant portion of arable farmland to rising sea levels.
In high-latitude regions, global warming will create favorable conditions for crop growth in areas previously too cold for agricultural productivity. The northern United States and northeastern Europe may benefit from the northward expansion of farmable land. There are, however, conflicting expectations for the productivity of new farmland. In Russia, for example, agronomists believe that projected future temperatures will positively affect agricultural productivity, but may cause a lack of water and an increased risk of drought.viii
Perhaps the most severe degradation of agricultural land will occur because of rising sea levels. Since 1993, the global sea level has risen between 2.6mm and 3.0mm annually and has accelerated rapidly in recent years.ix Rising temperatures globally and collectively increase sea levels by melting polar ice caps. From 2003 to 2010, over 4.3 trillion tons of ice were lost from Greenland, the Earth’s glaciers, and the North and South Poles.x Studies by the Intercontinental Panel on Climate Change (IPCC) suggest that the complete melting of Antarctica and Greenland would respectively cause a 60-meter and 7-meter rise in sea level. Melting of smaller ice concentrations and glaciers would have a much smaller effect, estimated roughly between a 2.5 and 7-meter rise in sea level.xi While Antarctic and Greenlandic ice sheets are not expected to melt entirely, the later figures (though modest in comparison) represent scenarios likely to occur within this decade. Moreover, future sea level estimates fail to consider the exponential nature of melting ice. Once ice caps melt to certain degree, water behaves as a lubricant, triggering more rapid melting.xii The IPCC reports that a significant rise in sea level would severely negative affect agriculture, primarily by submerging arable farmland, but also by reducing water and soil quality and by eroding of coasts, with transportation and food processing systems are also vulnerable to a rising sea level.
Agricultural Utilization of Carbon Dioxide
Carbon dioxide is essential to photosynthesis, as plants use energy from sunlight and water to convert the CO2 absorbed from the atmosphere into their food source, glucose. Rising CO2 concentration in the atmosphere can have both positive and negative consequences on many plant functions, with some variations between plant species. In controlled environments, a rise in CO2 has been strongly associated with increased plant growth and reproduction.xiii Studies suggest that under controlled, optimal conditions, a two-fold increase in CO2 can increase yields by as much as 36%.xiv There is, however, substantial uncertainty concerning how well these results hold given actual conditions.
Because rising CO2 stimulates crop growth, it also stimulates the growth of other plants, such as harmful weeds, fungi, pests and other unwanted plants. The expedited growth of these unwanted plants necessitates a greater use of pesticides and chemical fertilizers. Last year alone, US farmers spent over $11 billion on pesticides.xv This number is expected to increase in future years. The proliferated use of pesticides raises concerns about harmful chemicals entering food grown for human consumption. Rising CO2 has further implications on the nutritional quality of crops. According to the IPCC, crops grown in an abundance of CO2 have been shown to yield lower nutritional value. Higher CO2 levels are consistent with lower concentrations of protein and essential minerals in crops including wheat, rice, and soybeans.xvi Consequently, decreased nutritional quality may have severe implications on human health.
Climate change is expected to affect crops unevenly, as some crops are more resilient to fluctuations in their environment, while others are extremely sensitive to slight changes. The estimations of climate change’s impact on food security is well-indicated by agricultural products essential to human consumption: wheat, rice, and livestock. 729 million metric tons of wheat are produced annually and production continually increases.xvii Wheat is the most-consumed crop in the world overall, most frequently consumed in high-income countries. Conversely, rice is the most-consumed crop in the developing world, particularly in East and Southeast Asia, with rice production estimated at over 483.8 million metric tons in 2016.xviii
Case Study I: Wheat
The world currently produces more than 700 million tons of wheat annually, of which 500 million tons are converted directly into products for human consumption. A research study by Nature Climate Change (NCC) suggests that increasing temperatures are associated with significant decreases in wheat yields. This study gathered data from institutions in China, the U.S., Europe and globally to conclude that a one-degree Celsius increase in temperature may reduce global wheat productivity by 4.1 to 6.4 percent.xix To assess the impact of temperature changes on wheat production, researchers used statistical analysis reliant on historical observations of climate and global wheat yields to infer future productivity. In addition, the NCC used two different types of crop modeling simulations to integrate contextual differences between regions.
This study, though, had major limitations. As described earlier, crop growth is determined by several interrelated mechanisms, temperature being only one of these factors. The research study fails to consider increases in atmospheric CO2, which are associated with some increases in crop growth and increased efficiency in water usage. Neither is freshwater availability addressed in the study. Water availability is vital to crop growth regardless of temperature, and a drought-like conditions will dramatically reduce overall yields. Furthermore, adaptive capacity is not considered and likely has significant implications for ensuring wheat productivity. Because adaptive capacity relies on several indicators, including human resources, physical resources, financial resources, information and diversity,xx it differs considerably across regions and contexts. This makes it a reasonably difficult variable to incorporate into crop modeling. Nonetheless, it is a necessary factor to illustrate an accurate picture of future wheat yields.
Case Study II: Rice
Next, we will examine climate change effects on the most consumed crop in the developing world: rice. According to Food and Agriculture Organization (FAO), over 3 billion people are characterized as having very high dependence on rice (i.e. more than half of all calories consumed are from rice). Studies have suggested that high temperatures and other climate change effects will negatively affect rice production, since rice is most vulnerable to exposure to extreme temperatures. However, depending on the location, temperature increases may positively or negatively affect rice yields. In areas of colder, milder weather, temperature will likely have a positive effect on rice productivity, while in tropical and warmer climates—where the clear majority of rice is currently produced—modest temperature increases may significantly reduce yields. In the Philippines, a one-degree increase in growing season temperatures was linked to a 15% reduction in yield.xxi. Rice’s exposure to extremely high temperatures for just 1 to 2 hours during anthesis (roughly 9 days before heading) typically results in great damage to grain fertility.xxii
In the long-run, rice fields located in proximity to coastlines will be vulnerable to rising sea levels. Low-lying farmland, such as within Bangladesh, India, and Vietnam, will face significant reductions of rice cropland if sea levels rise as projected. In Vietnam, for example, most of the country’s rice is cultivated near the Mekong Delta. A comparatively modest rise in sea level of one meter would submerge large areas of rice paddies and likely render the country incapable of supporting its main staple and export.xxiii
Case Study III: Heat Stress on US livestock
Growth in the world economy continues to largely determine diets and food preferences. As wealth increases globally, so too does the demand for meat and livestock products. Most of the world’s meat is consumed in high-income countries, but this is quickly changing. In developing countries, the consumption of meat grows between 5-6% annually and the consumption of milk and dairy grows roughly 3.6% annually.xxiv
Climate change presents significant danger to livestock productivity. As with crop production, only appropriate environmental conditions ensure efficient production. Climate change is expected to impact animal agriculture in four major ways: feed-grain production, availability, and price; pastures and forage crop production and quality; animal health, growth, and reproduction; and disease and pest distributions.xxv Firstly, feed-grain production and forage crop production would be aggravated by climate change via the same mechanisms discussed in the previous section. Fluctuations in crop productivity will directly affect the supply of feed for livestock. Animal feed in the US, for example, is made from crops grown domestically. Secondly, livestock consumes 47% of all soy and 60% of all corn produced in the US.xxvi Decreases in the supply of feed grain may increase meat prices dramatically. Thirdly, heat stress on livestock has detrimental effects on health, productivity, and fertility. While most animals can adequately adjust to some deviations in temperature, most struggle to cope with extreme weather events. Deviations in core body temperature of greater than 4-5 degrees Fahrenheit stress livestock animals substantially, leading to severe losses in productivity and reproduction rates. Deviations in core body temperature of greater than 9 degrees Fahrenheit are often fatal.xxvii Livestock animals are far more vulnerable to temperature extremes than to increases in average temperature. And fourthly, high temperatures have been shown to decrease milk production, weaken the immune and digestive systems of animals, and increase the mortality rates of dairy cattle. On days where ambient temperatures exceed 90 degrees Fahrenheit, the risk of pig mortality doubles.xxviii
Research published by The University of Illinois and The Ohio State University analyzed the economic implications of heat stress on US livestock. The research suggested that, based on current trends, climate change is projected to increase average temperatures progressively for several years, threatening livestock productivity and by extension meat consumption. Evaluating the effects on dairy cows, beef cows, pigs, and chicken, the study uses weather data collected over a range of 68-129 years from 257 weather stations to calculate average monthly maximum and minimum temperatures and humidity for the continental United States. The researchers modeled the effects on livestock productivity and health on existing research on animal heat responses
The study found that the US livestock industries will experience severe economic losses. The researchers considered four scenarios of heat abatement adaptation ranging from minimal to intensive. With only minimum adaptive measures, estimates of economic losses averaged over $2.4 billion annually.xxix Even with exhaustive adaptive measures, losses averaged over $1.7 billion annually. In the model, the dairy and beef industries withstood the greatest losses ($897 million and $369 million respectively), likely because cows require extensive outdoor grazing and are sensitive to temperature. The poultry industry fared comparatively better ($128 million), as chickens are generally raised within indoor chicken coops. Severe economic losses to the meat and dairy industry may dramatically increase food prices. The US will likely have some of the world’s most sophisticated adaptive technology, but still suffer significant economic losses as fewer consumers purchase livestock products.
The Importance of Adaptation
Climate change threatens to aggravate food insecurity if production practices neglect making critical adjustments. In this case, adaptation, which involves adapting to changing climate, is necessary as it maximizes benefits and minimizes harms. Adaptation seeks to reduce the harmful effects of climate change on human development, and these adaptations range from as using air-conditioners to tolerate hotter temperatures, to altering consumption practices to compensate for agricultural limitations. Adaptation capacity is also closely tied to wealth. The wealthier a society, the greater its adaptability to changes in regional climate, with poorer societies having lesser adaptability and more vulnerability to the effects of climate change. Unfortunately, the poorer regions will be worst affected by climate change, while the wealthiest regions are expected to face the least harmful effects. There are three major challenges to achieving broader global food security: closing yield gaps, increasing production limits, and reducing food waste.
Firstly, “Yield gaps are the difference between the realized crop productivity of a place and what is attainable using the best genetic material, technology, and management practices”,xxx and represent a lack of productivity. Farmers in the United States, for example, typically grow over five times more corn per acre than farmers in Africa.xxxi Reducing yield gaps with modern technology and farming practices offers food-insecure populations the chance to more efficiently utilize available resources. On a global scale, yield gaps depend on fertilizer use, irrigation, and climate type. Many underperforming regions could increase production as high as 45%-70% if crops were managed better.xxxii Narrowing yield gaps is technologically feasible, since high-yielding modern crop varieties and nitrogen fertilizer demonstrate remarkable increases in productivity during the Green Revolution.1 China, India, and Pakistan transitioned from famine-plagued countries to ones that neared complete self-sufficiency.
However, considerable barriers exist to equipping Africa and other regions with the tools to close yield gaps. Providing agricultural technology and knowledge to large amounts of poor farmers requires strong political leadership and large public investments. These ambitions have been historically challenging even without the damaging effects of climate change, and future efforts may require considerably more effort to close these gaps.
Secondly, increasing agricultural production limits occurs in a variety of ways. Improved farming practices, technological advances, and alternate food source utilization catalyze new production potentials. In developed countries with low yield gaps, increasing production limits helps to maintain strong food market systems and enable the distribution of more aid to countries in need. Also, maintaining depositories of genetic material is critical to expanding yield potential. According to the USDA, maintaining large depositaries of various crop seed genotypes and genetic materials allows farmers to select optimal crop variations each season, based on soil, weather, and pest conditions. Diverse genetic material also allows scientists and agronomists to genetically engineer stronger plants to better resist pests, require less water, space, or nourishment.
Thirdly, broader global food security must be achieved by reducing food waste. Studies estimate that between 30% and 50% of food—over 1 trillion dollars’ worth—is wasted annually, with an estimated one in four calories produced agriculturally is never consumed.xxxiii In developing and low-income countries, food waste occurs because of failures in farming practices and processing. In developed countries, alternatively, most food waste occurs within households, as roughly 100kg (220 lbs.) of food per person is wasted by choosing to dispose of edible food before its expiration date or because of qualitative deficiencies.xxxiv
Because climate change influences agriculture and food security in complex and interdependent ways, many uncertainties still exist about how it will impact agriculture. The current evidence and most available research unfortunately only consider average effects and variations, not the extremes. The most intense of climate fluctuations and changes will have lasting consequences on food security. Whether food production and distribution can adapt to changes depends highly on a region’s means. Short-term predictions discuss conflicting effects of climate change on food security, for instance, that some regions may prosper because of climate change over the next 20 years. No matter fleeting benefits, though, the long-run predictions state with immense certainty that climate change will severely exacerbate global malnutrition and food insecurity. But if regions increase crop yields independent of climate change, only then can nations lessen its grim consequences.
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Footnotes & Endnotes
1 “The Green Revolution refers to a set of research and development of technology transfer initiatives occurring between the 1930s and the late 1960s that increased agricultural production worldwide, particularly in the developing world beginning most markedly in the late 1960s.” (Hazell 2009)
i Bita, 2006.
ii Hatfield, 2011.
iii Kindersley, 2008.
iv Luedeling, 2008.
v Glogoza, 2005.
vi Berglund, 2005.
vii Linkemer, 1998.
viii Kokorin, 2007.
ix Watson, 2015.
x NASA, 2012.
xi Zwally 2012.
xiii Sun, 2014.
xv Hatfield, 2014.
xvi Ziska, 2014.
xvii USDA, 2016.
xix Liu et al, 2016.
xx Defiesta et al, 2014.
xxi Nguyen, 2002.
xxiii IRRI, 2007.
xxiv Bruinsma, 2003.
xxv Rötter, 1999.
xxvi Olsen, 2006.
xxvii Gaughan 2009.
xxix St-Pierre et al, 2003.
xxx Godfray et al. 2010.
xxxi Gillis, 2011.
xxxii Mueller et al, 2012.
xxxiii Gustavsson et al., 2011; WRI, 2015.