CO₂ and Crops: The Yield Driver EU Policy Rarely Talks About

For decades, agricultural productivity has followed a reassuring narrative. Better genetics, improved agronomy, mechanisation, and smarter inputs have driven impressive growth. Since the 1940s, wheat yields have tripled, and maize yields have increased sixfold. The seed sector has played a central role in this transformation, delivering varieties that are higher-yielding, more resilient, and better adapted to farmers' needs. However, what if part of this productivity story has been unfolding quietly in the background, not in breeding programs or machinery sheds, but in the atmosphere itself?

A recent working paper from the US National Bureau of Economic Research (NBER) suggests that rising atmospheric carbon dioxide (CO₂) has contributed more to crop yield growth than most economic and policy models currently acknowledge. For European policymakers and the seed sector alike, this finding deserves careful attention.

The idea that CO₂ boosts plant growth is not radical. Plant physiologists have understood the fertilisation effect of CO₂ for over 200 years. Commercial greenhouse growers actively enrich CO₂ to accelerate photosynthesis and raise yields. The real debate has always been scale and relevance. Most existing estimates come from controlled experiments, such as growth chambers or Free-Air CO₂ Enrichment (FACE) trials, which are invaluable scientifically but limited geographically and operationally.

The NBER study takes a different approach. Instead of manipulating CO₂, it observes natural variation. Using data from NASA's Orbiting Carbon Observatory satellites, the researchers track year-to-year fluctuations in CO₂ over thousands of U.S. counties and link them directly to real-world yields of maize, soybeans, and winter wheat between 2015 and 2022.

The results reveal that rising CO₂ has significantly boosted crop yields, especially wheat, more than many EU climate models acknowledge. Satellite data show that CO₂ fertilisation has played a substantial role in agricultural productivity gains, particularly in regions with high crop coverage. This effect is most pronounced in areas with extensive wheat cultivation, where CO₂-driven yield increases have been substantial.

The study also highlights that CO₂ fertilisation has contributed to higher productivity in maize and soybean production. While the impact on soybeans is less pronounced than on wheat, the data still indicate a measurable effect. This suggests that CO₂ fertilisation is a broader factor in crop yield growth than previously thought.

Ignoring CO₂ fertilisation may overstate climate damage, misguide EU policy, and undervalue seed-sector innovation critical for future food security. Plant biology, agricultural economics, and the seed sector all matter today. The findings from the NBER study have significant implications for how policymakers approach climate change and agriculture.

For instance, if CO₂ fertilisation is a significant contributor to crop yields, it may mean that some of the negative impacts of climate change on agriculture are mitigated by the same greenhouse gases. This could alter the balance of risks and benefits associated with climate policies and agricultural practices.

Moreover, the study underscores the importance of the seed sector in adapting to changing environmental conditions. While CO₂ fertilisation can enhance yields, it does not negate the need for high-quality seeds that are resilient to pests, diseases, and changing climate conditions. In fact, the seed sector's role in delivering improved varieties becomes even more critical in the context of rising CO₂ levels and climate change.

The NBER study also raises questions about the accuracy of current climate models. If satellite data reveal a more significant impact of CO₂ on crop yields than models suggest, it may indicate that these models are underestimating the fertilisation effect. This could lead to overly conservative policy recommendations and missed opportunities for optimising agricultural productivity.

In conclusion, the role of CO₂ in driving crop yields is a critical factor that EU policy often overlooks. By ignoring CO₂ fertilisation, policymakers may be overestimating the negative impacts of climate change on agriculture and underestimating the potential benefits of certain practices. The seed sector, plant biology, and agricultural economics all have a vested interest in understanding and incorporating the effects of CO₂ on crop productivity. As we navigate the complex interplay between climate change, agriculture, and the seed sector, it is essential to consider the full range of factors at play, including the subtle but significant influence of rising CO₂ levels on crop yields.