More CO2 in the atmosphere will ‘green the planet’

Myth:

CO₂ is good for plants, so increased levels of CO₂ will ‘green the planet’ and increase agricultural production. 

Fact:

The plants we should be looking at are crops, not greenery in general. These do grow better with more CO₂, but they do not do well in higher temperatures, and you can’t have more CO₂ without more warming. Wheat is particularly susceptible to heat. [Climate sceptics often counter this by claiming that the rise in CO₂ is not being accompanied by hotter temperatures, but this requires them to deny that global warming is real – something most of them know isn’t true. So they cannot use this line of argument as a way of justifying inaction in the face of climate change.]

Recent scientific research has shown that as CO₂ levels increase, the nutritional content of crops decreases, due to a reduction in vital trace elements like zinc and iron. The incidence of crop diseases like wheat leaf rust and corn rust is also greater, as is the prevalence of weeds. In addition, some pests (like the Colorado potato beetle and the European grapevine moth) also thrive in higher temperatures.

Experiment by the US Department of Agriculture, to see the impact of increased CO₂ levels on plant growth. [Source: Flickr. Creator: US Department of Agriculture]

Sources:

“Plants cannot live on CO2 alone,” Skeptical Science. https://skepticalscience.com/co2-plant-food.htm

Steve Tally, “Rising CO2 due to climate change may not improve agriculture, model shows,” Purdue University, 7/3/17. https://www.purdue.edu/newsroom/archive/releases/2017/Q1/rising-co2-due-to-climate-change-may-not-improve-agriculture,-model-shows.html

Jason Daley, “Why More Carbon Dioxide May Not Lead to More-Productive Crops,” Sierra, 1/5/18

Elizabeth A. Ainsworth, Alvaro Sanz-Saez and Courtney P. Leisner, “Crops and rising atmospheric CO2: friends or foes?” Philosophical Transactions of the Royal Society of London, 29/5/25

Andrew Moseman, “Don’t plants do better in environments with very high CO2?” MIT Climate Portal, 11/5/26. https://climate.mit.edu/ask-mit/dont-plants-do-better-environments-very-high-co2