The Fertilizer Effect: Consensus Adjourned

One of the first things I learned about plants in grade school is that they consume carbon dioxide and produce oxygen, making them great partners for we humans who consume oxygen and produce carbon dioxide. I remember being struck by the simple symbiotic elegance of this balanced relationship. Carbon dioxide and oxygen, I learned, were both essential to life.

The discussion I hear today about carbon dioxide centers almost entirely upon its negative impact, and perhaps due to my interest in food dynamics, I specifically focus on the almost universally accepted claim that carbon-induced climate change will adversely affect global food security. But given carbon dioxide is an essential ingredient for plant life, wouldn’t higher C02 levels generate stronger crop growth? Might this at least mitigate, if not reverse, the yield drag expected from carbon emissions?

Hundreds of studies over the past 200+ years have demonstrated that higher levels of carbon dioxide are associated with faster, more robust plant growth (click HERE for a summary of what is often referred to as the “Fertilizer Effect”). The Plant Growth database organized by Craig Idso at the Center for the Study of Carbon Dioxide and Global Change suggests that increasing carbon dioxide by an additional 300 parts per million improves tree growth by 70%+, vegetable yields by 45%+, and grain yields by 35%+. Bjorn Lomborg, director of the Copenhagen Consensus Center, further notes that the fertilizer effect is actually enhanced at higher temperatures, suggesting that rising temperatures may in fact further improve yields.

So what? The fact that rising carbon dioxide levels may promote plant growth is rarely considered in discussions of climate change and global food security. It should be. Alex Epstein, author of The Moral Case for Fossil Fuels, suggests that the fertilizer effect is an “inconvenient fact” that merits serious consideration, particularly when thinking about one’s carbon footprint. What if less carbon meant less food? Does anyone think driving their Prius may be hurting the hungry?

The effectively uncontested popular agreement that carbon emission will only hurt agriculture necessitates that we follow legendary former General Motors CEO Alfred P. Sloan’s suggestion for combating consensus: “If we are all in agreement…then I propose we postpone further discussion of this matter…to give ourselves time to develop disagreement and perhaps gain some understanding….”