Environmental Drivers of Agricultural Productivity Growth: CO₂ Fertilization of US Field Crops

We present a novel methodology to estimate the CO₂ fertilization effect on crop yields using data from NASA's Orbiting Carbon Observatory satellites. Our study complements field and chamber experiments by examining county-level crop yields under actual growing conditions across the majority of US cropland. For identification, we utilize remotely sensed, year-to-year CO₂ anomalies from county-specific trends and further instrument for these anomalies using wind patterns. We find a CO₂ fertilization effect greater than that reported in most field and chamber experiments. In a thought exercise, we apply the CO₂ fertilization effect estimated in our sample from 2015–2022 backward to 1940. Assuming no other limiting factors, we find that rising CO₂ was a major driver of past yield growth, particularly for wheat—with important implications for estimates of future climate change damages.