In a commentary published on 3 December in Nature News & Comment, leading climate experts and scientists have laid out eight steps for recovering soil carbon stocks, which they believe could mitigate climate change and boost soil fertility.
Currently, one-third of the carbon dioxide (CO2) produced by humans is absorbed by plants, of which 10–15 per cent is distributed to soils. Furthermore, agriculture is highly dependent on carbon since it is the basis of soil fertility. Carbon releases nutrients for plant growth and promotes the structure as well as both the biological and physical health of soils. However, the amount of soil organic carbon present in soils can vary largely between regions and is based on the soil and landscape type. For example, the soil carbon content in rainforests can be more than 10 per cent, whereas levels in poor-quality, heavily exploited soils are closer to 1 per cent. Moreover, dwindling carbon levels in soils can lead to damage from erosion, heatwaves, and droughts.
The authors “call on countries involved in the Koronivia process to establish a body to monitor soil carbon in farmland, map changes to it and reclaim degraded areas.” The Koronivia Joint Work on Agriculture programme ― established at the 2017 Bonn climate conference in Germany to help farmers reduce emissions and ensure food security ― held its first workshop on 3 December at the annual summit of the United Nations Framework Convention on Climate Change (UNFCCC) in Katowice, Poland. However, improving soil carbon content has been on the political agenda since the 2015 Paris climate summit, which saw the launch of the 4p1000 initiative to promote research and actions globally to increase soil carbon stocks by 4 parts per 1,000 (0.4 per cent) per year. Around 3–4 gigatonnes per year ― equivalent to the yearly fossil-fuel emissions of the European Union ― could be removed from the atmosphere by increasing the carbon content of soils by just 0.4 per cent each year (1).
The eight steps are as follows:
1. Stop carbon loss
- Protect peatlands, which store 32% and 46% of all soil carbon.
- Restore mineral soils ― 10 million and 60 million square kilometres of soils are degraded ― by controlling grazing, applying green manure or growing cover crops.
2. Promote carbon uptake
- Establish a set of best practices for getting more carbon into soils.
- Increase biodiversity and plant nitrogen-fixing species, such as beans and alfalfa, which reduced the need for nitrogen fertilisers.
- Develop regional strategies that take into account soil types, climate, and socioeconomic issues.
3. Monitor, report and verify impacts
- Track and evaluate interventions by harmonizing protocols and standards and increasing technical expertise and knowledge, particularly in developing countries.
4. Deploy technology
- Use advanced instruments with harmonized methodologies, verification standards, and common guidelines will make soil measurements cheaper, faster, and more accurate.
5. Test strategies
- Develop computer models and networks that can assess the effectiveness of farming practices. This will require collecting data on soil types and meteorological variables.
6. Involve communities
- Public awareness of the importance of soil organic carbon and the role individuals can play, for example, by collecting data.
7. Coordinate policies
- Governments must work together to build appropriate political frameworks that govern soils and climate change.
- Soil carbon goals should be integrated into pledged emissions cuts set out in the Paris agreement.
- Global targets and policies should be used to reform agricultural practices.
8. Provide support
- Soil carbon should be included in emissions-trading schemes and carbon taxes and incentive like premiums and carbon credits could be awarded.
The authors argue that “increasing soil carbon stocks and protecting carbon-rich soils is crucial for achieving the Paris climate targets and [Sustainable Development Goals] SDGs” and must be recognised by researchers, policymakers, and land managers. Further to this, they suggest a pool should be set up containing several millions of dollars to address urgent research gaps. Finally, they urge governments to “pledge funds to bring together soil experts, donors, and policymakers to act on soil carbon storage.”
(1) Chabbi, A. et al. Aligning agriculture and climate policy. Nature (2017). DOI: 10.1038/nclimate3286