What satellite data reveal about productivity, plant biology and the blind spots in climate policy.
For decades, agricultural productivity has followed a reassuring narrative. Better genetics. Improved agronomy. Mechanisation. Smarter inputs.
The numbers are impressive. Since the 1940s, wheat yields have tripled. 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.
But what if part of this productivity story has been unfolding quietly in the background, not in breeding programmes or machinery sheds, but in the atmosphere itself?
A recent working paper (Dec. 2025) 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.
Moving Beyond Experiments: Measuring CO₂ Where Crops Actually Grow
The idea that CO₂ boosts plant growth is hardly 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 (e.g. in growth chambers or Free-Air CO₂ Enrichment [FACE] trials), which are invaluable scientifically, but limited geographically and operationally.
The NBER study takes a different route. 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.
In short: not how crops might respond under experimental conditions, but how they do respond on commercial farms.
What the Results Show, and Why Wheat Matters
The results are striking. According to the study, a 1 part-per-million (ppm) increase in atmospheric CO₂ is associated with average yield increases of:
- 0.17% for maize,
- 0.20% for soybeans
- 0.55% for winter wheat
These effects are larger than those reported in most field experiments, particularly for wheat, a crop of strategic importance to Europe.
The biological explanation is well established. Wheat and soybeans are C₃ crops, which respond directly to higher CO₂ during photosynthesis. Maize, a C₄ crop, benefits more indirectly through improved water-use efficiency. The study’s findings align closely with plant physiology.
Perhaps more provocatively, the authors suggest that CO₂ fertilisation may have accounted for a substantial share of historical yield growth, especially for wheat, since the mid-20th century, a period usually attributed almost entirely to technological progress.
A Blind Spot in Climate Impact Assessments
This is where the implications extend beyond agronomy into policy. Many statistical models used to estimate climate change damages to agriculture focus on temperature extremes and weather variability, and with good reason. Heat stress already imposes real yield penalties, and those risks are increasing. However, most of these models exclude CO₂ fertilisation altogether.
By contrast, process-based crop models typically include CO₂ effects. The result is a growing disconnect between two strands of climate impact assessment, leading to widely divergent estimates of future agricultural damage.
The NBER paper does not argue that CO₂ fertilisation outweighs climate risks. The authors are explicit: the fertilisation effect diminishes at higher concentrations, does not cancel out extreme heat, and may be accompanied by changes in crop quality and nutritional composition. But treating CO₂ solely as a pollutant, without acknowledging its biological role, risks systematic bias in policy-relevant modelling.
Implications for the Seed Sector
For the seed sector, the message is not complacency, it is complexity. CO₂ fertilisation does not act in isolation. Its impact depends on genetics, nutrient availability, water stress and temperature. That interaction places greater, not lesser, importance on plant breeding, particularly for varieties that can convert CO₂-driven photosynthesis into stable yields under increasingly variable conditions.
It also reframes innovation. Yield gains may reflect not only progress despite environmental change, but adaptation withinit, an important distinction when evaluating the role of breeding, biotechnology and regulatory frameworks.
For decades, agricultural productivity has followed a reassuring narrative. Better genetics. Improved agronomy. Mechanisation. Smarter inputs.
The numbers are impressive. Since the 1940s, wheat yields have tripled. 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.
But what if part of this productivity story has been unfolding quietly in the background, not in breeding programmes or machinery sheds, but in the atmosphere itself?
A recent working paper (Dec. 2025) 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.
Moving Beyond Experiments: Measuring CO₂ Where Crops Actually Grow
The idea that CO₂ boosts plant growth is hardly 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 (e.g. in growth chambers or Free-Air CO₂ Enrichment [FACE] trials), which are invaluable scientifically, but limited geographically and operationally.
The NBER study takes a different route. 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.
In short: not how crops might respond under experimental conditions, but how they do respond on commercial farms.
What the Results Show, and Why Wheat Matters
The results are striking. According to the study, a 1 part-per-million (ppm) increase in atmospheric CO₂ is associated with average yield increases of:
- 0.17% for maize,
- 0.20% for soybeans
- 0.55% for winter wheat
These effects are larger than those reported in most field experiments, particularly for wheat, a crop of strategic importance to Europe.
The biological explanation is well established. Wheat and soybeans are C₃ crops, which respond directly to higher CO₂ during photosynthesis. Maize, a C₄ crop, benefits more indirectly through improved water-use efficiency. The study’s findings align closely with plant physiology.
Perhaps more provocatively, the authors suggest that CO₂ fertilisation may have accounted for a substantial share of historical yield growth, especially for wheat, since the mid-20th century, a period usually attributed almost entirely to technological progress.
A Blind Spot in Climate Impact Assessments
This is where the implications extend beyond agronomy into policy. Many statistical models used to estimate climate change damages to agriculture focus on temperature extremes and weather variability, and with good reason. Heat stress already imposes real yield penalties, and those risks are increasing. However, most of these models exclude CO₂ fertilisation altogether.
By contrast, process-based crop models typically include CO₂ effects. The result is a growing disconnect between two strands of climate impact assessment, leading to widely divergent estimates of future agricultural damage.
The NBER paper does not argue that CO₂ fertilisation outweighs climate risks. The authors are explicit: the fertilisation effect diminishes at higher concentrations, does not cancel out extreme heat, and may be accompanied by changes in crop quality and nutritional composition. But treating CO₂ solely as a pollutant, without acknowledging its biological role, risks systematic bias in policy-relevant modelling.
Implications for the Seed Sector
For the seed sector, the message is not complacency, it is complexity. CO₂ fertilisation does not act in isolation. Its impact depends on genetics, nutrient availability, water stress and temperature. That interaction places greater, not lesser, importance on plant breeding, particularly for varieties that can convert CO₂-driven photosynthesis into stable yields under increasingly variable conditions.
It also reframes innovation. Yield gains may reflect not only progress despite environmental change, but adaptation withinit, an important distinction when evaluating the role of breeding, biotechnology and regulatory frameworks.
Why This Matters for EU Policy
- Climate impact models guide regulation and investment. Omitting CO₂ fertilisation risks overstating agricultural damage and misallocating resources.
- Food security assessments depend on yield realism. Wheat, in particular, remains central to European diets and trade balances.
- Innovation policy must reflect biological reality. Breeding and seed innovation operate at the intersection of genetics and environment, policy should too.
- Nuance strengthens credibility. Recognising countervailing effects does not weaken climate policy; it improves its scientific foundation.
