Tropical regions are often seen as sources of carbon to the atmosphere, based on satellite data and atmospheric models. However, these same regions also import large amounts of food to feed their growing human and livestock populations. When this imported food is consumed, it leads to carbon dioxide being released through respiration by people and animals—a process called anthropogenic respiration. Although this carbon is real, most carbon cycle models do not track where the food came from or how its carbon is released. Instead, the emissions from eating imported food are mistakenly counted as if they came from the tropical land itself.

In this study, we separate out these respiration emissions linked to food trade and include them explicitly in an atmospheric inversion model. We find that when this is done, tropical land appears to absorb more carbon than previously thought—about 0.5 billion tons more each year. This shows that food trade can shift the apparent location of carbon emissions, and that better tracking of these flows is essential for accurately understanding the tropical carbon balance.