Authors: Keith Shepherd and Rolf Sommer | Published: August 2nd, 2017
How we manage soils is crucial to tackling climate change. Today is Earth Overshoot Day, which aims to highlight the moment each year when our use of the planet’s resources tips into “overdraft”. The day helps to highlight why restoring landscapes, particularly soils, has benefits for food security, livelihoods and the climate.
The top metre of soils around the world contains about three times as much carbon as in our entire atmosphere. This means that soils can be a double-edged sword for tackling climate change.
Land-use change and degradation, such as clearing land for farming, releases the carbon bound up in soils, adding to the CO2 accumulating in the atmosphere. On the other hand, managing soils carefully and restoring their fertility means they can take up more carbon, helping to mitigate our CO2 emissions and thereby limiting climate change.
In a recent comment article in Nature, leading climate scientists identified achieving zero emissions from land-use changes and deforestation as one of six milestones that must be met within the next three years if we are to meet the goals set out in the Paris Agreement.
Restoring degraded lands is one promising option. For example, the 4 parts per 1000initiative (“4p1000”) aims to increase the carbon stored in the world’s soils by 0.4% per year in order to sequester the human-caused CO2 emissions that aren’t already absorbed by the land or oceans.
Recent analysis shows that 25-50% of this target (equivalent to 0.9-1.85bn tonnes of carbon per year) could be achieved on the 16 million square kilometres of suitable farmland across the world. This would sequester about 6-13% of all CO2 emissions from human activity.
Our research has identified several relatively simple, low-cost options for restoring African landscapes to help cut emissions from soils and even turn them into carbon sinks.
Here are three that are key to reaching zero emissions from land:
Soil and water conservation
Water is essential for productive soils, but it can also be disastrous. Heavy rainfall events – likely to become more intense as the climate warms – washes soil off the land, particularly hillsides or in areas with highly erodible soil types. This strips the land of its nutrients, reduces agricultural productivity, and clogs waterways and reservoirs, thus increasing costs for purifying drinking water.