Arguments
Is CO2 plant food? Why are we still talking about this?
Posted on 26 February 2025 by Guest Author
This is a re-post from The Climate Brink by Andrew Dessler
Recent interviews with Trump administration officials have revived a persistent myth in climate change discussions: “CO2 is plant food”. This is one of those zombie climate-denial arguments that just never goes away because 1) it’s a simple argument and 2) it seems intuitive — after all, plants need carbon dioxide, so more of it must be good, right?
Yes, CO2 enhances photosynthesis. But crops don’t grow in a vacuum, they also need water, temperatures in a particular range, and farmers need predictable seasons. Climate change disrupts all of those.
The Earth is greening, but only partially due to enhanced CO2. The observed greening in India and China, for example, are mainly due to aggressive reforestation programs, farm subsidies, and irrigation projects designed to sustain high agricultural output — not rising CO2 levels.
If climate change aids agriculture anywhere, it’s at high latitudes, where it benefits few people. Meanwhile, the world’s major breadbaskets — places like the U.S. Midwest, India, and parts of Africa — are seeing more frequent heat waves, floods, and droughts. The reality is that climate change makes agriculture more difficult almost everywhere.
The “CO2 is plant food” myth survives because it’s a convenient lie, not because it’s true.
Here are some peer-reviewed articles on this nuanced question:
-
Anthropogenic climate change has slowed global agricultural productivity growth
-
Climate change has likely already affected global food production
-
New science of climate change impacts on agriculture implies higher social cost of carbon
I posted this about “CO2 is plant food” in June of 2023. That was right after we started the blog, so a lot of you didn’t see it. So here it is again:
I read on Twitter that “CO2 is plant food.” That didn’t seem right, so I asked David Lobell, one of the world’s experts on climate change and agriculture. He’s a professor at Stanford, a MacArthur genius grant recipient, a member of the National Academy of Sciences, and an all-around good guy.
Here’s what he said:
The bottom line:
Me: So are you worried about the climate impacts on agriculture?
David Lobell: Yes. I think the evidence is very clear that, on net, the changes going on in the atmosphere, including all the climate changes, are a risk to a lot of major production systems and to a lot of food insecure areas. So there's definitely a reason that we that we continue to work on how to adapt to these changes.
So next time someone says “CO2 is plant food,” please send them this post.
Water is also 'plant food': no water, no plant. So... more water is good, right? Just flood that garden and you'll enjoy a bountiful harvest (or maybe not).
People can't live long without water. 'Drowning' is, nevertheless, still a thing.
Technically, CO_2 is plant food. But it is just a misleading truth to state it out in the open without letting people know the drawbacks associated with the other consequences of the increase in CO_2. So I sympathize with people wanting to call it a "myth" but I don't think it is a "myth" in the strict sense.
People have many roles. A person may be a father, a brother, a son, an employee, a hunter, the list goes on and on. Nobody has just a single role.
It is likely that your boss cares more about your role as an employee than your role as a brother. The role that matters is situational.
CO2 is plant food, carbonator of drinks, key component of CO2 lasers, dry ice, greenhouse gas, the list goes on. The role we care about is situational. CO2 does not have a single role.