By : Shaurya Agarwal

Abstract

Human activities are increasing atmospheric carbon dioxide levels and raising global temperatures. This has accelerated plant growth across ecosystems worldwide, a phenomenon known as the “greening of the Earth.” However, there’s a trade-off: These fast-tracked plants would contain fewer nutrients per bite. This stands to hold severe repercussions for humans dependent on cereal crops that are affected by higher concentrations of carbon in this manner. Along with animals that depend upon plant-based diets for their survival.

Introduction

The planet is warming at an alarming rate. The effects of human-caused global climate change are becoming more and more apparent as we witness more record-breaking heat waves, intense droughts, shifts in rainfall patterns and a rise in average temperatures. These environmental changes stand to affect almost every part of crop production. Carbon dioxide is the primary greenhouse gas responsible for the increase in Earth’s global temperature. Carbon dioxide by general practice is removed from the atmosphere by plants during photosynthesis, (though not in quantities sufficient enough to remove everything humans emit). However, interestingly, recent greenhouse and field experiments have shown that higher levels of carbon dioxide in the atmosphere can even act as a fertiliser and increase plant growth. The amount of benefit a crop receives depends on its type. For example, wheat, barley and rice benefit more from higher carbon dioxide concentrations than corn. More carbon dioxide in the air makes the plant more efficient at absorbing the gas, and consequently, it loses less water during the process of photosynthesis, which is better for the plant’s growth. With sufficient water and other nutrients, crop yields can increase significantly. However, those higher yields often come with major drawbacks for nutrition. Crops grow faster and bigger under higher CO2, but the protein and micronutrient content is proportionally lower. This phenomenon, known as nutrient dilution, results in reduced levels of vital micronutrients such as iron, zinc, copper, and magnesium in major food crops. More efficient CO2 absorption allows plants to lose less water during photosynthesis, increasing their growth. However, their ability to absorb and concentrate nutrients does not keep pace, leading to lower nutritional quality in the food supply.

This trend extends beyond cultivated crops to wild plant species, disrupting entire food webs. Research suggests that carbon dioxide fertilisation explains about 70% of the observed greening effect where plants grow bigger and faster with nitrogen availability and climate change impacts accounting for the rest. Regions with nutrient-poor soils, such as parts of Australia and tropical areas like the Amazon and Congo basins, remain especially vulnerable to these changes. Even marine ecosystems are experiencing nutrient declines, as warmer waters reduce the nutritional quality of critical species such as sea kelp, which forms the base of many oceanic food webs. 

Food Security and Health Concerns 

A recent international study from China, Japan, Australia, and the United States assessed the effects of rising CO2 levels on rice nutrition. The data showed for the first time that rice grown at the concentrations of atmospheric carbon dioxide scientists expect the world to reach by 2100 has lower levels of four key B vitamins. In particular, human deficiencies in iron, zinc and protein are starkly expected to increase in the coming decades because of rising carbon dioxide levels. These declines are expected to have broad impacts on human health and even survival, with the strongest effects among populations that are highly dependent on rice and wheat, typically located in East and Central Asia. Long-term records of crop nutritional values have revealed recurring declines in copper, magnesium, iron and zinc. These findings also stand to support research from other field studies showing that rice grown under such conditions contains less protein, iron and zinc, which are important in fetal and early child development. These changes stand to disproportionately impact maternal and child health in the poorest rice-dependent countries, including Bangladesh and Cambodia. According to the United Nations food security report 90% of the world’s rice is produced and consumed in Asia. Over 70% of the world’s poor are in Asia. 

Research suggests that major cereal crops – particularly rice and wheat – respond to higher CO2 concentrations by synthesising more carbohydrates (starches and sugars) and less protein hence reducing the quantity of minerals in their grains. Higher carbon concentrations in plants also reduce nitrogen amounts in critical plant tissues, which is critical for forming B vitamins. Different B vitamins are required for key bodily functions, such as regulating the nervous system, turning food into energy and fighting infections. Folate, a B vitamin, reduces the risk of birth defects when consumed by pregnant women. Insufficient dietary iron can lead to iron deficiency anaemia, a condition in which there are very few red blood cells in the body to carry oxygen. This is the most common type of anaemia. It can cause fatigue, shortness of breath or chest pain, and can lead to serious complications, such as heart failure and developmental delays in children. Hence, causing widespread health and food security concerns among countries with lower food purchase parity and that remain critically dependent on rice consumption as one of the stable food sources for their giant and ever-growing population.

The economic impacts of declining plant nutrition are vast, affecting things ranging from farm productivity to global trade. For example, regions heavily dependent on nutrient-poor staple crops like rice and wheat could see heightened rates of micronutrient deficiency in their growing populations, particularly in youth. This would exacerbate malnutrition and increase healthcare costs, particularly in low-income countries. Food processing industries may also face new challenges. As nutritional quality declines, food manufacturers may need to alter product formulations or seek alternative sources for raw materials, potentially driving up production costs. This, in turn, could lead to higher consumer prices and reduced food accessibility.

Declining plant nutrition isn’t just a human concern—it also holds serious implications for wildlife and livestock. Livestock producers report and are worried over recurring diminished weight gains, particularly in cattle feeding on protein-depleted grasses. This poses a direct challenge to agricultural productivity and profitability, further straining food security systems worldwide. The nutritional value of livestock feed is also declining. Cattle spend a lot of time eating and often have difficulty finding enough protein to meet their needs. Protein concentrations are falling in grasses across rangelands around the world. This trend threatens livestock and ranchers, reducing animals’ health, and overarching life quality and costing producers money.

 Effects on Animals

Declining plant nutrition does not only affect humans; it also threatens livestock and wildlife. These changes in plants aren’t the most visually evident, like rising seas. Nor are they sudden and imminent, like hurricanes or heat waves. But they can have important impacts over time. More than one-third of all animals on Earth, from beetles to cows to elephants, depend on plant-based diets. Due to their low-calorie count, plants pose an energy consumption challenge for animals. Climate change exacerbates this by diminishing the nutritional content of plants consumed by herbivores. Consequently, these animals spend more time foraging, increasing their vulnerability to predators and other threats. Diminished nutritional value also hinders growth, reproduction, and survival. A concerning case is that of the endangered giant panda, a species of significant cultural importance. Because they reproduce at low rates and need large, connected swaths of bamboo as habitat, they are classified as a vulnerable species whose survival is threatened by land conversion for farming and development. One notable example is the giant panda, an endangered species reliant on bamboo. The giant panda is considered an “umbrella species,” which means that conserving panda habitat benefits many other animals and plants that also live in bamboo groves. Now, rising temperatures are reducing bamboo’s nutritional value and making it harder for the plant and the pandas to survive.

In zones that are less affected by human activity, evidence suggests that changes in plant chemistry may play a role in decreasing insect numbers. Many insects are plant feeders that are likely to be affected by reduced plant nutritional value. Experiments have found that when carbon dioxide levels increase, insect populations decline, at least partly due to lower-quality food supplies. It becomes important to note here that not all insect species are declining, as not all plant-feeding insects respond in the same way to nutrient dilution. Insects that chew leaves, such as grasshoppers and caterpillars, suffer the most precarious effects, including reduced reproduction and smaller body sizes. In contrast, locusts prefer carbon-rich plants, so increasing carbon dioxide levels could cause increases in locust outbreaks. The effects on insect populations also highlight potential biodiversity loss, endangering multiple symbiotic relationships between insects and plants and hence critically damaging present-day food ecosystems.

Call for Further Investigation 

The long-term outlook for global food systems highlights the urgent need for coordinated international action. While the carbon dioxide fertilisation effect may provide temporary increases in crop yields, the accompanying nutrient dilution underscores the dire need for innovation in sustainable agriculture.  CO2 – induced alterations have substantial implications for medicinal plants, nutrition, food safety, and food allergies. Considering the potentially destructive impact, investment in research is imperative. Mitigation strategies may include developing climate-resilient crop varieties that maintain high nutrient levels, improving soil management practices, and employing precision agriculture technologies to optimise resource utilisation. Furthermore, conservation initiatives focused on protecting vulnerable ecosystems and biodiversity remain crucial for maintaining balanced food webs and synergistic ecosystems.

Author’s Bio 

Shaurya Agarwal is currently in the final year of his liberal arts program at the Jindal School of Liberal Arts and Humanities. His research interest lies in the areas of environmental economics and public policy. 

Image Source : AP