Desertification is the degradation of land in arid, semi-arid, and dry sub-humid areas. It is caused primarily by human activities and climatic variations.
Desertification does not refer to the expansion of existing deserts. It occurs because dryland ecosystems, which cover over one third of the world's land area, are extremely vulnerable to over-exploitation and inappropriate land use.
Poverty, political instability, deforestation, overgrazing, and bad irrigation practices can all undermine the land's productivity. Over 250 million people are directly affected by desertification.
In addition, some one billion people in over one hundred countries are at risk. These people include many of the world's poorest, most marginalized, and politically weak citizens.

Combating desertification is essential to ensuring the long-term productivity of inhabited drylands. Unfortunately, past efforts have too often failed, and around the world the problem of land degradation continues to worsen.
Recognizing the need for a fresh approach, 179 governments have joined as of March 2002, the United Nations Convention to Combat Desertification. This Convention aims to promote effective action through innovative local programmes and supportive international partnerships.
The treaty acknowledges that the struggle to protect drylands will be a long one - there will be no quick fix. This is because the causes of desertification are many and complex, ranging from international trade patterns to unsustainable land management practices. Real and difficult changes will have to be made, both at the international and the local levels.

Countries affected by desertification are implementing the Convention by developing and carrying out national, sub-regional, and regional action programmes. Criteria for 'preparing these programmes are detailed in the treaty's - five "regional implementation annexes": Africa (considered a priority because that is where desertification is most severe), Asia, Latin America and the Caribbean, the Central and Eastern Europe and the Northern Mediterranean.

The DesertWatch project focuses on the latter.

In the short-term the DesertWatch project aims at developing a user-tailored, standardised, commonly accepted and operational information system based on EO technology to support national and regional authorities of Annex IV countries in reporting commonly to the UNCCD and assessing and monitoring desertification and its trends over time.

This will contribute to:

• The creation of standard and comparable geo-information products from country to country about the status and trends in desertification.
• The creation of a common framework for reporting to the UNCCD for Annex IV countries;
• The creation of a common basic infrastructure as a base for further developments where EO plays a key role.
• The development of a common methodological approach for all countries in Annex IV to assess and monitoring the desertification problems and identify trends and potential scenarios;