After an iron chemical test conducted in an alluvial area of South Africa, red color reveals positive conditions to the storage of organic carbon.

© IRD - Vincent Chaplot

4 per 1000 initiative

Updated 25.04.2019

Capturing carbon in the air and storing it in the ground to fight climate change: this is the goal of the ambitious 4 per 1000 strategy. This initiative, the subject of an international research programmeis mobilising several teams at the IRD.

Combining cereals and leguminous plants, here, cowpea, allows to improve land’s quality thanks to nitrogen’s capture.

© IRD -Tiphaine Chevallier

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During the 24th Conference of the Parties to the United Nations Framework Convention on Climate Change (COP24) held from 3 to 14 December 2018 in Poland, there was a lot of discussion around the 4 per 1000 strategy launched by the French government on 1 December 2015 during COP21.

Supported by 300 governments, research establishments, agricultural organisations, NGOs, and banks, this initiative sprang from a striking observation: on a planetary scale, agricultural and forest lands store two times as much carbon as the atmosphere. “Carbon in the air is sequestered by plants during the biological process of photosynthesis?A process allowing green plants to synthesise organic matter from carbon dioxide (CO2) and light. and can then be found in the roots and even the soil itself after the aerial parts of the plants are broken down by bacteria”, explained Jean-Luc Chotte, a soil scientist and director of the mixed research unit Eco & Sols. Hence the idea to optimise this natural process of sequestering all or part of the carbon dioxide (CO2) emitted by human activities since it is responsible for climate change. “To counteract the annual increase in CO2 emissions”, Jean-Luc Chotte clarified, “you just need to increase carbon storage in the top 30 to 40 centimetres of soil by just 0.4% per year, or 4 per 1000, hence the name of the initiative”. 

A need for multidisciplinary efforts

In order for these efforts to succeed, research needs to rise to several major challenges:“Better understanding the mechanisms of carbon sequestration in the soil, identifying plants that can increase this storage, developing techniques for measuring it, determining if storage can be affected by climate change, and defining how best to assist farmers to promote storage”, Chotte enumerated.

Experts from multiple disciplines including soil specialists, agronomists, physicians, sociologists, and even economists are being brought together through the 4 per mil initiative. At the IRD, the effort is mobilising several teams. For example, the Espace-Dev unit is working on remote detection technology to assess the state of soils and the Eco & Sols unit is studying the determining factors of the carbon cycle in agrosystems. Several International Combined Laboratories are also involved such as the LUSES ICL in southeast Asia and the IE-Sol ICL in West Africa.

By relying on these research organisations, the interdisciplinary and partnership-based structural programme (PSIP) “Continental carbon sequestration” was launched in 2016. Uniting different scientific skill sets, it aims to structure thought to identify means to increase carbon stores in the ground.

© IRD - IRA - Christian Lamontagne

Crop residues’s input, like palm tree, allows to improve the storage of organic carbon in lands.

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Bring together different groups of people working on sustainable development

Several important results in the field have already been published. In May 2018, a team including researchers from the Eco & Sols laboratory showed that the more organic carbon was provided in the form of manure or waste from harvesting, the more carbon tropical soil could store2. “These results suggest that efforts to increase carbon storage in the soil should be focused on practices that increase organic input”, concluded the authors. 

Jean-Luc Chotte went further, arguing that “it is absolutely necessary to intensify research in this field”. This is, moreover, one of the goals of the seminar on the 4 per mil initiative that was held in Sète, France on 7 & 8 November 2018: calling for funding that reflects the challenges and urgency of fighting climate change. Furthermore, Jean-Luc Chotte added: “The role of the 4 per mil initiative is also to foster dialogue between the various actors involved in sustainable development including: scientists, NGOs, professional organisations, and policy makers.” It's quite the undertaking.

Note :
1. Kenji Fujisaki, Tiphaine Chevallier, Lydie Chapuis-Lardy, Alain Albrecht, Tantely Razafimbelo, Dominique Masse, Yacine Badiane Ndour, Jean-Luc Chotte, Soil carbon stock changes in tropical croplands are mainly driven by carbon inputs: A synthesis, Agriculture, Ecosystems & Environment, 21 mars 2018

Contact : Jean-Luc Chotte