It is undoubtedly the least known of the COPs, compared to those on climate and biodiversity, but it nonetheless addresses a major issue. The 16th session of the Conference of the Parties to the United Nations Convention to Combat Desertification (UNCCD) opens in Riyadh, Saudi Arabia, on Monday, December 2. Countries around the world will try, during this COP described as“historical” by the United Nations, to limit the expansion of deserts and the progressive decline in the quality of soils, vegetation, water resources or fauna.
The objectives of the event are multiple. “Countries should agree on how to deal with the crucial issue of drought”explains the executive secretary of the UNCCD, Ibrahim Thiaw, also citing the acceleration of land restoration and the taking into account of “most vulnerable communities”.
Currently, desertification threatens “40% of the planet's land surface”reports the Institute of Research for Development (IRD), and affects 3.2 billion people, specifies the UNCCD. “All continents are affected by land degradation, not one is spared”warns Jean-Luc Chotte, research director at IRD and president of the French Scientific Committee on Desertification.
This is shown, in part, in the following map, from the sixth report of the Intergovernmental Panel on Climate Change (IPCC), published in 2022. It identifies arid zones in the world (in brown) and their expansion (in red) between the years 1901-1930 and the years 1988-2017.
The aridity index, used to produce this map, presents a “global vision linked to climate change”explains Mehrez Zribi, CNRS research director at the Center for Spatial Studies of the Biosphere. Many reference documents – such as the atlas of the European Commission's research center – are based on this index to account for desertification.
In a special report devoted to land, the IPCC, however, warns about its use. The group considers that assessing the complex phenomenon of soil degradation should instead be done by combining three indicators: the evolution of land cover, the loss of productivity and the decline in organic carbon storage in soils.
It remains that “the scale and intensity of desertification has increased in some arid areas in recent decades”establishes the IPCC. Latin America and Asia are the continents with the highest proportion of damaged land, but the latest trends “show that Africa is deteriorating considerably faster than the global average”alerts the Convention in a tool allowing the evolution of the situation in different regions to be compared. The African continent thus saw the deterioration, between 2015 and 2019, of 250 million hectares of additional land.
The European continent is not left out. “We think that the desert is far away. This is totally false”points out Jean-Luc Chotte. “Many soils are deteriorating, eroded, and their stock of organic matter is decreasing”he describes, citing the examples of Spain and the south of France.
“Soil fertility is decreasing, water reserves are decreasing, biodiversity is decreasing. We are in a system that is becoming more and more fragile. We produce less and of lower quality”adds the researcher. For him, fighting against desertification is therefore “fight against food and nutritional insecurity, but also adapt, mitigate climate change and conserve biodiversity”.
