Among the main challenges in the twenty-first century are the rapid increase in the world population, the degradation of agricultural soils and the release of greenhouse gases in the atmosphere that contribute to climate change. These three important issues are closely linked as land-use management options that prevent soil degradation can also decrease the emission of greenhouse gases, enhance carbon sequestration (CS), and improve food security. While the growing population is leading to a higher demand for food, the agricultural land per capita is decreasing, particularly in Asia, Africa and South America, the regions with the highest demographic expansion. Human activities such as fuel consumption and land-use change are the main causes of an increase in the atmospheric carbon-dioxide concentration, which is generally recognized as a factor of climate change and global warming.
FAO has implemented several collaborative programmes to assist developing countries in the adoption of land-management practices that reverse the current land degradation, desertification and inadequate land use. At a general level, these programmes promote land-management practices that provide economic and environmental benefits to the farmers taking into account different aspects at economic, sociological and environmental levels.
As part of its activities on soil CS within the framework of its integrated land management programme, the FAO Land and Plant Nutrition Management Service, Land and Water Development Division, initiated a one-year project at the beginning of 2002. Its aim was to collect, assess and elaborate the state of the art on the use of CS to improve land-use management in dryland areas of the world. This programme is closely linked to the FAO Land Degradation Assessment in Drylands (LADA) project that aims to develop and test an effective assessment methodology for land degradation in drylands. The programme is also linked with the Convention to Combat Desertification and the Convention on Biological Diversity (CBD) with, as its final aim, the provision of up-to-date information for the formulation of policy and technical options for the development of sustainable systems in drylands. While increasing CS, sustainable land-use systems can improve the livelihood of farmers through soil conservation, enhancement and protection of agrobiodiversity.
In the current political and international framework, the implementation of the United Nations Framework Convention on Climate Change and the agreement of the Kyoto Protocol have created new possibilities to implement specific initiatives and projects that stimulate CS. For example, the Clean Development Mechanism (CDM) enables developed countries to buy carbon credits from developing countries by establishing specific projects that enhance CS in these areas. However, this mechanism is unlikely to be applicable in drylands, and other multilateral approaches need to be explored and developed where synergies between different conventions and funds are strengthened. Whereas CS may not be a priority in poor countries, land-use management options that increase CS may also be beneficial for plant production, prevention of erosion and desertification, and biodiversity conservation, which are of major interest in these regions. Therefore, actions for soil improvement through CS are a win - win situation where increases in agronomic productivity may help mitigate global warming, at least in the coming decades, until other alternative energy sources are developed. There have been important advances in the last few years at political, scientific and awareness levels and numerous projects are being implemented.
This report aims to review and summarize the current state of the art in CS in order to analyse how available resources and specific programmes can be implemented in drylands, one of the most soil-degraded regions of the world. Other FAO publications produced under this programme have considered other aspects of CS: methodological issues related to carbon monitoring and accounting, CS options to address land degradation under the CDM, general aspects of CS, and specific CS projects.
With this analysis, the document aims to highlight the current problems and uncertainties and to produce recommendations for the development of specific strategies and policies that can be implemented in dryland areas to improve land management that enhances CS.
