Earth Chat

More CO2 hurts—not help—plants




After two back-to-back record hottest years, meteorologists predict some relief for 2025. The bad news is that it will likely be the third hottest year on record.[1]

The average global temperature for 2025 is forecast to be between 1.29°C and 1.53°C (with a central estimate of 1.41°C) above the average for the pre-industrial period (1850-1900). (Image source: Met Office)

The warming influence of El Niño may have helped push temperatures up for 2023 and 2024, but the main culprit is still climate change, driven by carbon dioxide and other greenhouse gases emitted through human activities.[2] Reducing emissions and achieving carbon neutrality thusly should be important steps to limit global warming; yet you may come across the occasional sceptics claiming that since plants need CO2 to grow, climate efforts are harmful to farming and the planet.

Spoiler alert: High CO2makes plants less nutritious (Image source: Synnefa)

Reality of course is more than just grade school science. While more CO2 may increase crop yield, it worsens nutritional quality. Specifically, they were found to be starchier from absorbing more CO2, but in turn containing less proteins and minerals important to health.[3] These deficiencies negatively impact cognitive development, metabolism, obesity, diabetes, and other health outcomes, potentially influencing health and well-being throughout an individual's life course.[4]


The claim also misses the nuance that excess CO2 in the atmosphere doesn’t happen in isolation; it is driving climate change, making the world hotter, rainfall more intense, and extreme weather more frequent and severe. Coffee lovers, for instance, may soon see prices surging this year, as both Brazil and Vietnam—the world’s two largest coffee growers—have been hit by droughts and heavy rain. Other crops, such as rice and oranges, have also suffered from poor harvests due to climate-driven diseases and extreme weather.[5],[6]

A farmer collects crops in a rice field flooded by extreme rain in Jiangxi province, China (Image source: NewScientist)

Furthermore, global warming has created a dangerous cycle, where hotter and drier conditions are causing more wildfires and releasing more CO2from the Amazon and other forests.[7],[8]In the tundra, thawing permafrost is also allowing microbes to access and break down previously-frozen ancient plant matter into carbon.[9]


Fires and the climate feedback loop (Image source: World Resource Institute)

 

Agriculture is a particularly climate-vulnerable sector. Any potential yield gains that increasing atmospheric CO2 may bring are offset by the negative climate impacts in more crop failures and poorer nutritional quality. Farmers must be empowered to adopt sustainable agricultural practices to better buffer farms against current and future climate risks. Agroforestry, intercropping, and mulching are just a few examples of practices that can improve climate resilience and conserve ecosystem functions, while also maintaining crop yields.

Global warming is happening, and climate change is real. 2024 was the year the world first breached the 1.5°C warming limit temporarily. We are running out of time, but we can still prevent the worst of climate impacts by making immediate and deep cuts to greenhouse gas emissions.




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