The 3rd edition of the World Atlas of Desertification was published by the European Union in June 2018. Since the publication of the first Atlas in 1977, the environment has undergone enormous global changes due largely to human activities. Fortunately, significant progress has been made in understanding human- environment interactions. Thus, the 3rd edition of the World Atlas of Desertification provides new insights on the challenging topic of land degradation.

In particular, the Atlas focuses on land degradation and global environmental change under five major subject headings:

Global Patterns of Human Domination
The central theme of the Atlas is an acknowledgement that humans are at the core of global environmental change, in particular, human activities are responsible for land degradation as well as extensive deforestation. Global population is projected to reach 8.3 billion by 2030 and 10-12 billion by the end of this century. In this context, the Atlas emphasises that exponential increases in human population and changes in patterns of consumption have created unprecedented pressure on the Earth’s natural resource base and led to resource depletion and driven environmental change. The Atlas explores human footprints on Earth such as artificial lighting, infrastructure expansion, migration to urban areas, urbanisation and forest changes.

Feeding a Growing Global Population
Against the background of growing world population - nearly 3 billion people will be added to the global middle class by 2030, the key question is whether a growing human population will outstrip the ability of agriculture to meet its food demands. The Atlas reveals that most of the productive lands in the globe have already been converted to agriculture. Lands not converted to agriculture are forests, wetlands and grasslands, and converting them to agriculture would have serious environmental costs in terms of increasing greenhouse gas emissions and losses of biodiversity. Alternatively, food production can be increased via the practice of “sustainable intensification”. In this context, the Atlas explores the global expanse of agriculture and explains crucial aspects of the dynamics food production in relation to land degradation.

Limits to Sustainability
In light of climate change, human population growth and widespread environmental degradation, the Atlas finds that resources consumption has its limits. As regards desertification, it is understood that unsustainable human activities put the land resource at risk. In particular, soils sustain the diverse agricultural production systems of the Earth, filter and regulate freshwater dynamics. Since degradation of previously productive soils cannot be reclaimed in human timescales, we have to understand the limits of the biophysical envelope that sustains life on Earth. The Atlas explores patterns of aridity, water stress, the status of soils, dynamics of vegetation and biodiversity.

Convergence of Evidence
Land degradation is not a phenomenon that can be modelled or mapped at a global scale. The most fundamental challenge is making global data on human environment interactions useful. Attempting to interpret global data at the local level tends to undermine confidence in virtually any global assessment. Thus, the Atlas applies principle of “convergence of evidence”, which entails dynamic, abductive logic to ascertain what a given finding means “on-the- ground”. These findings are analysed and a ‘most likely explanation’ of accumulated evidence that relates to land degradation is found. Afterwards, such “most likely explanation” is translated into a hypothesis, inference, explanation, conclusion or best guess about that status of land degradation at a given location.

Solutions
There is no “one size fits all” solution to desertification and land degradation. Potential solutions can only be identified and implemented within the context of localised social, economic and political conditions. The concept of sustainable land management evolved in response to the need for solutions to problems associated with land degradation is based on the principles of enhancing the productivity and protection of natural resources while maintaining an economically viable use of the land. When successful solutions are found, the challenge is to define similar contexts to which those solutions might be applicable. In this context, the Atlas offers a number of findings that emerge from multiple issues related to land degradation and its geographic and temporal coincidence.

The Atlas concludes that land degradation is a global problem determined by the local social, economic and ecological context in which it occurs. Nonetheless, the Atlas identifies following trends:

I. Underlying and familiar factors -- some old, some new -- are driving environmental change/land degradation at a global scale;
II. Some recurring global issues (such as surface and ground water) have an alarming urgency that could not be known 20 years ago;
III. There is a growing confirmation of suspected global trends (such as a decline in productivity) that may impact sustainability;
IV. Global issues that were only suspected previously will shape how we look at both processes and solutions (such as telecouplings; smallholders vs. largeholders);
V. Some regional patterns of potential degradation are reconfirmed (south Asia; China) and some underlying causes are revealed (heavy fertiliser use and irrigation);
VI. New regional patterns of potential land degradation are revealed (especially in central Asia);
VII. Concerns emerge at the regional level that brings into question our ability to meet the demands of future populations, e.g. maintaining and increasing yields on highdensity croplands and increasing crop yields (by closing yield gaps) on low-density and low-input croplands;