Deploying ocean iron fertilization—a strategy for carbon dioxide capture—in higher latitudes rather than near the equator could reduce environmental impacts while still achieving removal of carbon dioxide from the atmosphere, according to a modeling study published in Nature. The findings offer insight into best practices for maximizing carbon dioxide removal while reducing potential ecological trade-offs typically associated with iron fertilization.

Current carbon emissions are projected to surpass the Paris Climate Agreement’s limit of 2°C above preindustrial levels. Ocean iron fertilization—in which iron is added to surface water to stimulate phytoplankton growth for carbon dioxide removal—is a potential solution. However, the ecological impacts of this strategy, such as creating runaway algal blooms and depleting nutrients in the water, have been a limitation.

Jun Yu, Adam Martiny and colleagues used an ocean iron fertilization model to assess the climate benefits and ecological trade-offs of the approach. By analyzing more than six decades of fertilization data, they found that net carbon dioxide removal was up to 5.3 parts per million, which corresponds to a removal rate of 0.70 gigatons of carbon dioxide per year.