More CO2 hurts—not help—plants
2025-01-10
| Policy Research and Advocacy Team, Friends of the Earth (HK)
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.