La Convención ofrece nuevas esperanzas para luchar contra la desertificación

En las últimas décadas el problema de la degradación de tierras en las regiones de zonas secas ha seguido empeorando. La Convención promueve un nuevo método para gestionar los ecosistemas de tierras secas y administrar las aportaciones de ayuda al desarrollo.

The Kyoto Protocol negotiated in the mid-1990s to address climate change adaptation and mitigation will expire in 2012. This protocol represents one of the two milestones that the multilateral negotiation of climate change has delivered. Ten years after its adoption, the climate change negotiators decided upon the second largest milestone when they approved the Bali Action Plan at their 2007 meeting in Bali.

The Kyoto Protocol negotiated in the mid-1990s to address climate change adaptation and mitigation will be replaced by a post-Kyoto agreement in 2012. The new agreement under negotiation needs to seal the policy gaps in adaptation and mitigation that were omitted or excluded from Kyoto on account of scientific uncertainties. Particular attention needs to be given to the potential of land in all its dimensions considering its high capacity to store carbon. Land stores twice as much organic carbon as vegetation and the atmosphere combined.

Drylands have the potential to play a big role in climate mitigation and, in doing so, to deliver significant co-benefits

Land use practices contribute to both the emission and sequestration of greenhouse gases. Land is where the struggle to adapt to climate change will be won or lost by the poorest of the poor. Land science is a priority area of collaboration between UNCCD and UNFCCC, if land-climate insights and actions are to be optimized. It can also foster the synergies continually called for by Parties to the three sister Rio Conventions.

The drylands of Africa, exclusive of hyper-arid zones, occupy about 43 per cent of the continent, and are home to a rapidly growing population that currently stands at about 325 million people. Dry zones, inclusive of hyper-arid lands, cover over 70 per cent of the continent’s terrestrial surface. Outside of the cities many dryland inhabitants are either pastoralists, sedentary or nomadic, or agro-pastoralists, combining livestock-rearing and crop production where conditions allow.

Comme la Préface l’a souhaité, ce document est conçu comme un plaidoyer. Son objectif, en effet, est de montrer pourquoi il faut aujourd’hui replacer la Convention de Lutte contre la Désertification au cœur des stratégies engagées pour affronter la crise montante de l’écosystème global. Son point de départ est un constat sans appel : la progression de la désertification et de la dégradation des terres et des eaux conduisent inéluctablement à un développement non durable (Chapitre I).

Desertification is defined as land degradation in arid, semi-arid and dry sub-humid areas, resulting from various factors, including climatic variations and human activities. More than one third of the surface of the earth consists of drylands. In terms of population, one out of every five people of the world live in already degraded or desertification-prone drylands. These people include many of the world’s poorest, most marginalized, and politically weak citizens. For instance, nearly 325 million people in the African continent live in drylands.

Avant-propos La notion de désertification se définit comme une dégradation des sols en zone aride, semi-aride et subhumide sèche, souvent appelée simplement « zone aride ». On estime qu’elle résulte d’une combinaison de facteurs, parmi lesquels les changements climatiques et l’activité humaine. Plus d’un tiers de la superficie totale de la terre est considéré comme zone aride. En termes démographiques, c’est un cinquième de la population totale du globe qui vit en zone aride déjà dégradée ou menacée de désertification.

Participatory digital mapping using satellite imagery and digital earth and other open source Geographic Information Systems (GIS) is a practical tool bridging the knowledge and communication gap between pastoral communities and county government planners. It is offering an effective option for participatory planning and decision-making in support of climate change adaptation in the drylands of Kenya.

Climate warming during the past century has imposed recession of glaciers and perennial snow/ice patches along the entire Swedish Scandes. On the newly exposed forefields, subfossil wood remnants are being outwashed from beneath ice and snow bodies. In Scandinavia, this kind of detrital wood is a previously unused source of postglacial vegetation and climate history. The present study reports radiocarbon dates of a set of 78 wood samples, retrieved from three main sites, high above modern treelines and stretching along the Swedish Scandes.

The general trend of climatically-driven treeline advance is modified by regional, local and temporal variations. Treelines will not advance in a closed front parallel to the shift of any isotherm to higher elevations and more northern latitudes. The effects of varying topography on site conditions and the after-effects of historical disturbances by natural and anthropogenic factors may override the effects of slightly higher average temperatures. Moreover, the varying treeline-forming species respond in different ways to a changing climate.