Global land degradation hotspots based on multiple methods and indicators

Land degradation is a major impediment to achieving sustainable development. However, there is currently no harmonized global map of land degradation status and hotspots. This paper aims to obtain the status and hotspots map of global land degradation by multiple methods and indicators to give essential references for land degradation neutrality. The results show that there are significant differences in the distribution and degree of land degradation between the different methods and indicators. Validation through observation points reveals that most of the methods and indicators can reflect land degradation in arid and semi-arid areas, while there are suitable methods or indicators in tropical and high-latitude areas. The degree of degradation has a large difference after overlay analysis, which shows that there are shortcomings of different methods and indicators for monitoring the degree of land degradation. However, the overlay of land degradation extent displays a high consistency, reflecting the current state of global land degradation to a certain extent. These areas with high overlay value can be recognized as hotspots of land degradation. It is also found there are consistent water-energy change characteristics in the hotspot area, such as increased land surface temperature and air temperature and decreased soil moisture and precipitation. These results conclude that studies on the degree of land degradation need to be considered in an integrated manner about the regional background. The combination of multiple methods and indicators is recommended for land degradation extent studies in large areas. Comparison of different methods and indicators is important guidance for global land degradation research. Accelerating ecological monitoring and restoration of land degradation hotspots is the first step towards land degradation neutrality.