More CO2 in the atmosphere hurts key plants and crops more than it helps
The familiar adage – too much of a good thing is a bad thing – applies to atmospheric carbon dioxide: In higher concentrations, it is a damaging pollutant.
YaleClimateConnections 12/2020
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"..For example, the atmosphere has a specific recipe. CO2 and other greenhouse gases are an essential part of the recipe because they trap heat in the atmosphere. With no CO2 Planet Earth would be in a perpetual ice age. But a small amount of CO2 keeps the planet in the famous “Goldilocks and the Three Bears” condition: not too hot, not too cold, but the “just right” zone that’s ideal for life as we know it. Too much CO2 overheats the planet.
By studying Earth’s history, scientists have learned that when there was a lot of CO2 in the atmosphere, the planet was hot. In fact, the last time the Earth had as much CO2 in the atmosphere as it now does was the Pliocene Epoch, more than 3 million years ago. At that time, Earth’s atmosphere was
3.6 to 7.2 degrees Fahrenheit warmer (2 to 4 degrees Celsius) than it is today. And global sea level was 50 to 80 feet (15 to 25 meters) higher.
Climate change is hard on plants.
The basics of climate change are actually easy to understand. Human activities emit around
100 million tons of CO2 every day, mostly by burning fossil fuels, which causes the atmosphere to trap more heat. As a result of that heat-trapping pollution, the atmosphere, land, and oceans have all
become warmer. The added heat triggers side effects like more intense rainstorms, floods, prolonged heat waves, and droughts. In turn, those unpleasant conditions lead to more frequent and severe wildfires, insect outbreaks, and crop failures. Sure, today’s plants have a bit more fertilizer from the extra CO2 in the air, but that additional CO2 causes many other problems, harming many plants and crops. Climate change is disrupting plant growth.
Agricultural experiments show negative effects.
Scientists have performed many experiments to see what happens when plants and agricultural crops receive extra CO2. When supplemental CO2 was pumped into the air around plants, they grew faster. For this reason, CO2 is sometimes piped into enclosed greenhouses to boost production. But greenhouse plants also have optimal amounts of water, excellent soil, and controlled temperatures. It’s usually a different story out in the real world.
To conduct a more “real world” experiment, other studies have given plants extra CO2 plus an increase in temperature. In these conditions, many plants and crops grew poorly. In most cases, the boost from CO2
was overwhelmed by the hotter conditions. These experiments demonstrate that the myth of CO2 fertilization is false, and peer-reviewed
reports find that major crops like wheat, rice, corn, and soybeans
will become less productive as the world heats up.
Likewise, a landmark
study in 2018 found that growing rice in high-CO2 conditions makes it less nutritious. As a basic grain, rice plays a critical role in feeding the world’s population. The extra CO2 caused an imbalance within the crop’s chemical makeup, which resulted in rice that had lower amounts of protein, iron, zinc, and B-vitamins. “The entire elemental balance is out of whack,” explained plant physiologist Lewis Ziska, an author of the study. This result is yet another example of how the recipe of nature is being disrupted by excess CO2.
Common Climate Misconceptions: Atmospheric Carbon Dioxide
Bad news can lead to our making needed changes.
Myths that try to “disprove” climate change can be appealing. Nobody loves the idea that human-caused pollution is now altering the chemical balance of Earth’s atmosphere. Nevertheless, climate change is happening.
But we can use our improving knowledge to prevent these problems from getting worse and maintain a healthy climate for plants and people.
The familiar adage - too much of a good thing is a bad thing - applies to atmospheric carbon dioxide: In higher concentrations, it is a damaging pollutant.
yaleclimateconnections.org
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