The rise in carbon dioxide leads to poor quality food on Earth

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

An article about the works of a Georgian scientist who, having arrived in the United States, in addition to mathematics, took up biology. He began to observe changes in plant life depending on the quality of air and light. The conclusion was ecological: the growth of carbon dioxide in the atmosphere accelerates the growth of plants, but deprives them of substances useful to humans.

Irakli Loladze is a mathematician by education, but it was in the biological laboratory that he faced a riddle that changed his whole life. This happened in 1998, when Loladze was receiving his doctorate from the University of Arizona. Standing by glass containers shining with bright green algae, one biologist told Loladze and half a dozen other graduate students that scientists had discovered something mysterious about zooplankton.

Zooplankton are microscopic animals that swim in the world's oceans and lakes. They feed on algae, which are essentially tiny plants. Scientists have found that by increasing the flow of light, it is possible to accelerate the growth of algae, thereby increasing the supply of food resources for zooplankton and having a positive effect on its development. But the hopes of scientists did not come true. When researchers began to cover more algae, their growth really accelerated. Tiny animals have a lot of food, but, paradoxically, at some point they were on the verge of survival. The increase in the amount of food should have led to an improvement in the quality of life of the zooplankton, and in the end turned out to be a problem. How could this happen?

Despite the fact that Loladze formally studied at the Faculty of Mathematics, he still loved biology and could not stop thinking about the results of his research. The biologists had a rough idea of what happened. More light made the algae grow faster, but ultimately decreased the nutrients needed for zooplankton to reproduce. By accelerating the growth of algae, the researchers essentially turned them into fast food. The zooplankton had more food, but it became less nutritious, and therefore the animals began to starve.

Loladze used his mathematical background to help measure and explain the dynamics depicting the dependence of zooplankton on algae. Together with colleagues, he developed a model that showed the relationship between a food source and an animal that depends on it. They published their first scientific paper on this topic in 2000. But apart from this, Loladze's attention was riveted on the more important question of the experiment: how far can this problem go?

“I was amazed at how widespread the results were,” recalled Loladze in an interview. Could grass and cows be affected by the same problem? What about rice and people? “The moment when I started thinking about human nutrition was a turning point for me,” the scientist said.

In the world beyond the ocean, the problem is not that plants are suddenly getting more light: they have been consuming more carbon dioxide for years. Both are necessary for plants to grow. And if more light leads to fast-growing but less nutritious "fast food" algae with poorly balanced sugar-to-nutrient ratios, then it would be logical to assume that increasing carbon dioxide concentration could have the same effect. And it can affect plants all over the planet. What does this mean for the plants we eat?

Science simply did not know what Loladze discovered. Yes, the fact that the level of carbon dioxide in the atmosphere increased was already well known, but the scientist was struck by how little research has been devoted to the effect of this phenomenon on edible plants. For the next 17 years, continuing his mathematical career, he carefully studied the scientific literature and data that he could find. And the results seemed to point in one direction: The effect of the fast food he learned about in Arizona was showing up in fields and forests around the world. “As CO₂ levels continue to rise, every leaf and blade of grass on Earth is producing more and more sugars,” Loladze explained. "We have witnessed the biggest injection of carbohydrates into the biosphere in history - an injection that dilutes other nutrients in our food resources."

The scientist published the data he collected just a few years ago, and it quickly attracted the attention of a small but rather concerned group of researchers who raise troubling questions about the future of our nutrition. Could carbon dioxide have an effect on human health that we have not yet studied? It seems that the answer is yes, and in search of evidence, Loladze and other scientists had to ask the most pressing scientific questions, including the following: "How difficult is it to conduct research in a field that does not yet exist?"

In agricultural research, the news that many important foods are becoming less nutritious is not new. Measurements of fruits and vegetables show that the content of minerals, vitamins and protein in them has decreased markedly over the past 50-70 years. Researchers believe the main reason is quite simple: when we breed and select crops, our top priority is higher yields, not nutritional value, while varieties that yield more yields (be it broccoli, tomatoes, or wheat) are less nutritious. …

In 2004, a thorough study of fruits and vegetables found that everything from protein and calcium to iron and vitamin C had dropped significantly in most horticultural crops since 1950. The authors concluded that this is mainly due to the choice of varieties for further breeding.

Loladze, in the company of several other scientists, suspects that this is not the end, and that perhaps the atmosphere itself is changing our food. Plants need carbon dioxide in the same way that people need oxygen. The level of CO₂ in the atmosphere continues to rise - in an increasingly polarized debate about climate science, it never occurs to anyone to dispute this fact. Before the industrial revolution, the concentration of carbon dioxide in the Earth's atmosphere was about 280 ppm (parts per million, a millionth is a unit of measurement of any relative values, equal to 1 · 10-6 of the base indicator - ed.). Last year, this value reached 400 ppm. Scientists predict that in the next half century, we will probably reach 550 ppm, which is twice as much as it was in the air when Americans first started using tractors in agriculture.

For those with a passion for plant breeding, this dynamic may seem positive. Moreover, this is how politicians used to hide behind, justifying their indifference to the consequences of climate change. Republican Lamar Smith, chairman of the US House Science Committee, recently argued that people shouldn't be so worried about rising carbon dioxide levels. According to him, it is good for plants, and what is good for plants is good for us.

"A higher concentration of carbon dioxide in our atmosphere will promote photosynthesis, which in turn will lead to an increase in the rate of plant growth," wrote a Republican from Texas. "Food products will be produced in greater volumes, and their quality will be better."

But as the zooplankton experiment has shown, more volume and better quality don't always go hand in hand. On the contrary, an inverse relationship can be established between them. Here's how the best scientists explain this phenomenon: the increasing concentration of carbon dioxide accelerates photosynthesis, a process that helps plants convert sunlight into food. As a result, their growth accelerates, but at the same time they also begin to absorb more carbohydrates (such as glucose) at the expense of other nutrients we need, such as protein, iron and zinc.

In 2002, while continuing his studies at Princeton University after defending his doctoral dissertation, Loladze published a solid research paper in the leading journal Trends in Ecology and Evolution, which argued that increasing carbon dioxide levels and human nutrition are inextricably linked to global changes in plant quality. In the article, Loladze complained about the lack of data: among thousands of publications on plants and rising carbon dioxide levels, he found only one that focused on the effect of gas on nutrient balance in rice, a crop that billions of people rely on to harvest. (An article published in 1997 deals with the drop in zinc and iron levels in rice.)

In his article, Loladze was the first to show the effect of carbon dioxide on the quality of plants and human nutrition. However, the scientist raised more questions than he found answers, rightly arguing that there are still many gaps in the study. If changes in nutritional value occur at all levels of the food chain, they need to be studied and measured.

Part of the problem, it turns out, was in the research world itself. To obtain answers, Loladze required knowledge in the field of agronomy, nutrition and plant physiology, thoroughly flavored with mathematics. The last part could be dealt with, but at that time he was just beginning his scientific career, and the departments of mathematics were not particularly interested in solving problems of agriculture and human health. Loladze struggled to secure funding for new research and at the same time continued to maniacally collect all the possible data already published by scientists from around the world. He went to the central part of the country, to the University of Nebraska-Lincoln, where he was offered the position of assistant to the department. The university was actively engaged in research in the field of agriculture, which gave good prospects, but Loladze was just a teacher of mathematics. As it was explained to him, he can continue to carry out his research, if he himself finances them. But he continued to fight. In the distribution of grants at the Department of Biology, he was refused due to the fact that his application pays too much attention to mathematics, and at the Department of Mathematics - because of biology.

“Year after year, I got rejection after rejection,” recalls Loladze. - I was desperate. I don't think people understood the importance of research."

This question was left out of the board not only in mathematics and biology. To say that the decrease in the nutritional value of staple crops due to an increase in the concentration of carbon dioxide is little studied is an understatement. This phenomenon is simply not discussed in agriculture, health and nutrition. At all.

When our reporters contacted nutrition experts to discuss the topic of the study, almost all of them were extremely surprised and asked where they can find the data. One leading scientist from Johns Hopkins University replied that the question was quite interesting, but admitted that he did not know anything about it. He referred me to another specialist who also heard about it for the first time. The Academy of Nutrition and Dietetics, an association of a large number of nutrition experts, helped me connect with nutritionist Robin Forutan, who was also unfamiliar with the study.

“It's really interesting, and you're right, few people know,” Forutan wrote after reading some papers on the topic. She also added that she would like to explore the issue more deeply. In particular, she is interested in how even a small increase in the amount of carbohydrates in plants can affect human health.

“We don’t know what a small change in carbohydrate content in food could end up with,” Forutan said, noting that the overall trend towards more starch and higher carbohydrate intake seems to have something to do with the increased incidence of disease. dietary related such as obesity and diabetes. - How much can changes in the food chain affect this? We cannot say for sure yet”.

We asked one of the most famous specialists in this field to comment on this phenomenon - Marion Nesl, professor at New York University. Nesl deals with issues of food culture and health care. At first, she was rather skeptical about everything, but promised to study in detail the available information on climate change, after which she took a different position. “You convinced me,” she wrote, also expressing concern. - It is not entirely clear whether the decrease in the nutritional value of foods caused by an increase in the concentration of carbon dioxide can significantly affect human health. We need a lot more data."

Christy Eby, a researcher at the University of Washington, is studying the link between climate change and human health. She is one of the few scientists in the United States who is interested in the possible serious consequences of changes in the amount of carbon dioxide, and she mentions this in every speech.

There are too many unknowns, Ebi is convinced. "For example, how do you know that bread no longer contains the micronutrients that were in it 20 years ago?"

The link between carbon dioxide and nutrition did not immediately become apparent to the scientific community, Ebi says, precisely because it took them a long time to seriously consider the interaction of climate and human health in general. "This is how things usually look," says Eby, "on the eve of change."

In Loladze's early work, serious questions were posed, to which it is difficult, but quite realistic, to find answers. How does an increase in atmospheric CO₂ concentration affect plant growth? What is the share of the effect of carbon dioxide on the drop in nutritional value of food in relation to the share of other factors, for example, growing conditions?

Running a farm-wide experiment to find out how carbon dioxide affects plants is also a difficult, but doable, task. Researchers use a method that turns the field into a real laboratory. An ideal example today is the free-air carbon dioxide enrichment (FACE) experiment. In the course of this experiment, scientists in the open air create large-scale devices that spray carbon dioxide onto plants in a specific area. Small sensors monitor the CO₂ level. When too much carbon dioxide leaves the field, a special device sprays a new dose to keep the level constant. Scientists can then directly compare these plants to those grown under normal conditions.

Similar experiments have shown that plants growing in conditions of increased carbon dioxide content undergo significant changes. So, in the C3 group of plants, which includes almost 95% of the Earth's plants, including those that we eat (wheat, rice, barley and potatoes), there was a decrease in the amount of important minerals - calcium, sodium, zinc and iron. According to forecasts of the reaction of plants to changes in the concentration of carbon dioxide, in the near future the amount of these minerals will decrease by an average of 8%. The same data also indicate a decrease, sometimes quite significant, in the protein content in C3 crops - in wheat and rice by 6% and 8%, respectively.

In the summer of this year, a group of scientists published the first work in which attempts were made to assess the impact of these changes on the population of the Earth. Plants are an essential source of protein for people in the developing world. Researchers estimate that 150 million people are at risk of protein shortages by 2050, especially in countries like India and Bangladesh. Scientists have also found that 138 million will be at risk due to a decrease in the amount of zinc, which is vital for the health of mothers and children. They estimate that more than 1 billion mothers and 354 million children live in countries that are predicted to decrease the amount of iron in their food, which could exacerbate the already serious risk of widespread anemia.

Such forecasts have not yet applied to the United States, where the diet of most of the population is diverse and contains enough protein. However, researchers note an increase in the amount of sugar in plants and fear that if this rate continues, then there will be even more obese and cardiovascular problems.

The USDA is also making significant contributions to research on the relationship of carbon dioxide to plant nutrition. Lewis Ziska, a plant physiologist with the Agricultural Research Service in Beltsville, Maryland, has written a number of nutritional papers that elaborate on some of the questions Loladze posed 15 years ago.

Ziska devised a simpler experiment that did not require growing plants. He decided to study the nutrition of bees.

Goldenrod is a wild flower considered by many to be a weed, but essential for bees. It blooms in late summer and its pollen is an important protein source for these insects during the harsh winter. People have never specially grown goldenrod or created new varieties, so over time it has not changed much, unlike corn or wheat. Hundreds of specimens of goldenrod are stored in the huge archives of the Smithsonian Institution, the earliest dating back to 1842. This allowed Ziska and his colleagues to trace how the plant has changed since that time.

The researchers found that since the industrial revolution, the protein content of goldenrod pollen has dropped by a third, and this drop is closely related to the rise in carbon dioxide. Scientists have long been trying to figure out the reasons for the decline in populations of bees around the world - this could have a bad effect on the crops for which they are needed to pollinate. In his work, Ziska suggested that the decrease in protein in pollen before winter may be another reason why bees find it difficult to survive in winter.

The scientist worries that the effects of carbon dioxide on plants are not being studied at a sufficient rate, given that changing agricultural practices could take a long time. “We do not yet have the opportunity to intervene and start using traditional methods to fix the situation,” Ziska said. “It will take 15-20 years for the results of laboratory tests to be put into practice”

As Loladze and his colleagues have found, new overarching, cross-cutting questions can be quite complex. There are many plant physiologists around the world who study crops, but they mostly focus on factors such as yield and pest control. It has nothing to do with nutrition. According to Loladze's experience, the departments of mathematics are not particularly interested in food products as objects of research. And the study of living plants is a long and expensive business: it will take several years and serious funding to get enough data during the FACE experiment.

Despite the difficulties, scientists are increasingly interested in these questions, and in the next few years they may be able to find answers to them. Ziska and Loladze, who teaches mathematics at Brian's College of Health Sciences in Lincoln, Nebraska, is working with a team from China, Japan, Australia, and the United States on a major study on the effects of carbon dioxide on the nutritional value of rice, one of the world's most important crops. In addition, they are studying the change in the amount of vitamins, important food components, which until now has practically not been done.

Recently, USDA researchers conducted another experiment. To find out how higher CO₂ levels affect crops, they took samples of rice, wheat, and soybeans from the 1950s and 1960s and planted them in plots where other scientists had grown the same varieties many years ago.

At the USDA research field in Maryland, scientists are experimenting with bell peppers. They want to determine how the amount of vitamin C changes with an increased concentration of carbon dioxide. They also study coffee to see if the amount of caffeine is dropping. “There are still a lot of questions,” Ziska said while showing the research facility in Beltsville. "This is just the beginning."

Lewis Ziska is part of a small group of scientists who are trying to evaluate changes and find out how they will affect people. Another key character in this story is Samuel Myers, a climatologist at Harvard University. Myers is at the head of the Planetary Health Alliance. The goal of the organization is to re-integrate climatology and health care. Myers is convinced that the scientific community is not paying enough attention to the relationship between carbon dioxide and nutrition, which is only part of a much larger picture of how these changes can affect the ecosystem. “This is just the tip of the iceberg,” Myers said. "We had a hard time getting people to understand how many questions they should have."

In 2014, Myers and a team of scientists published a major study in the journal Nature that looked at key crops grown at multiple sites in Japan, Australia and the United States. In their composition, a decrease in the amount of protein, iron and zinc was observed due to an increase in the concentration of carbon dioxide. For the first time, the publication has attracted real media attention.

“It is difficult to predict how global climate change will affect human health, but we are ready for the unexpected. One of them is the relationship between an increase in the concentration of carbon dioxide in the atmosphere and a decrease in the nutritional value of C3 crops. Now we know about it and can predict further developments,”the researchers write.

In the same year, in fact, on the same day, Loladze, at that time teaching mathematics at the Catholic University of Daegu in South Korea, published his own article - with data that he had collected for over 15 years. This is the largest study ever of increasing CO₂ concentration and its effect on plant nutrition. Loladze usually describes plant science as "noisy" - as in scientific jargon, scientists call an area in which is full of complex disparate data that seem to "make noise", and through this "noise" it is impossible to hear the signal you are looking for. His new data layer was finally large enough to recognize the desired signal through the noise and detect the "hidden shift," as the scientist called it.

Loladze found that his 2002 theory, or rather the strong suspicion he voiced at the time, turned out to be true. The study involved nearly 130 varieties of plants and more than 15,000 samples obtained in experiments over the past 30 years. The total concentration of minerals such as calcium, magnesium, sodium, zinc and iron fell by an average of 8%. The amount of carbohydrates relative to the amount of minerals increased. Plants, like algae, were becoming fast food.

It remains to be seen how this discovery will affect humans, whose main diet is plants. Scientists who dive into this topic will have to overcome various obstacles: the slow pace and obscurity of research, the world of politics, where the word "climate" is enough to stop any talk of funding. It will be necessary to build absolutely new "bridges" in the world of science - Loladze speaks about this with a grin in his work. When the article was finally published in 2014, Loladze included a list of all funding denials in the app.