Soils as carbon sinks

World Soil Day: Opinion piece by Dr Jacqueline Hughes, Director General, ICRISAT.

November 2022 was a watershed moment when the world population crossed 8 billion. In 2011 the world population was 7 billion and by 2050 it is expected to touch 9.8 billion. The world’s population more than tripled between 1950 and 2020. More than half of the projected increase in the global population up to 2050 will be concentrated in eight countries: the Democratic Republic of the Congo, Egypt, Ethiopia, India, Nigeria, Pakistan, the Philippines and Tanzania. Countries of sub-Saharan Africa are expected to contribute more than half of the increase anticipated through 2050.

Agricultural production must ramp up to feed a growing population. This can be achieved either by bringing more land under cultivation or through ''sustainable intensification", that is by closing yield gaps on under-performing lands. However, the first option, converting forests and grasslands to cropland, releases the stored carbon thus contributing to climate change. The Global Carbon Budget 2022 report released during the COP27 deliberations in Egypt showed that carbon dioxide emissions from land use changes is projected to be 3.9 billion tons in 2022. Therefore, in light of the Paris climate accords and the fact that emissions are already at unsustainable levels (total 40 billion tons in 2022), it is clear that pursuing the land use conversion route will only aggravate the climate crisis.

How can agriculture feed 9.8 billion people by 2050 and yet contribute to mitigating climate change. The answer lies in viewing soils in a different light. The concept of “negative emissions technology”, essentially removing and sequestering carbon dioxide from the air, has been gaining ground. Recent analyses suggest that deploying negative emissions technologies may be less expensive and less disruptive than reducing certain kinds of emissions. With other technologies such as bioenergy with carbon capture and storage, and afforestation, soil carbon sequestration is one of the main approaches to carbon removal and storage. Scientists have estimated that soils—mostly, agricultural ones—could sequester over a billion tons of carbon each year. Part of the attraction of soil carbon sequestration is that increases in soil carbon content are highly beneficial in enhancing soil health and soil fertility leading to improved crop yields.

See https://pressroom.icrisat.org/soils-as-carbon-sinks