Destruction of nutrient rich top soil as a result of factors such as over-intensive agriculture continues be a problem throughout the world and is advancing the desertification of drylands, such as those in Africa and the Mediterranean, a meeting in London heard today.
Luc Gnacadja, executive secretary of the United Nations Convention to Combat Desertification (UNCCD) told the meeting that top soil has a “value higher than gold” but that the urbanised world thought of it as “just dirt”.
“It takes 500 years to develop 20cm of top soil,” he said.
The meeting was organised to mark the launch of the United Nation’s ‘decade for deserts’ and the fight against desertification, which will run from 2010- 2020. The initiative aims to raise awareness of the issue among policymakers and financial donors.
The climate change agenda, in particular its “overemphasis” on forests, has “overlooked” drylands and their potential role as carbon sinks, commented Alison Rosser, who researches biodiversity and food security at the United Nations Environment Programme’s World Conservation Monitoring Centre in Cambridge, UK.
“One quarter of the world’s carbon stocks are held in the soil so there is big potential for investment to encourage land owners to keep the carbon in their soils,” she says.
Drylands cover about 41% of the world’s land surface but more needs to be known about the value of the ecosystems in these areas, Rosser says. The Economics of Ecosystems and Biodiversity (TEEB) studies to assess the global economic benefits of biodiversity didn’t cover drylands, she says. (See an opinion article Nature by Pavan Sukhdev, TEEB study leader)
She called for a greater recognition of the value of drylands as ecosystems.
“Desertification is here and it’s more real than climate change,” says José Luis Rubio, a soil scientist and head of the European Society for Soil Conservation.
But Michael Mortimore, a geographer and founder of Drylands Research, a consortium on dryland management in African countries, stressed that there is some good news. Satellite data is beginning to show that the drylands in some areas across the world, including the Sahel – the belt of dry land that runs from the west to the east coast of Africa – are becoming greener, he said.