Global cycling and climate effects of aeolian dust controlled by biological soil crusts

Biological soil crusts (biocrusts) cover similar to 12% of the global land surface. They are formed by an intimate association between soil particles, photoautotrophic and heterotrophic organisms, and they effectively stabilize the soil surface of drylands. Quantitative information on the impact of biocrusts on the global cycling and climate effects of aeolian dust, however, is not available. Here, we combine the currently limited experimental data with a global climate model to investigate the effects of biocrusts on regional and global dust cycling under current and future conditions. We estimate that biocrusts reduce the global atmospheric dust emissions by similar to 60%, preventing the release of similar to 0.7 Pg dust per year. Until 2070, biocrust coverage is expected to be severely reduced by climate change and land-use intensification. The biocrust loss will cause an increased dust burden, leading to a reduction of the global radiation budget of around 0.12 to 0.22W m(-2), corresponding to about 50% of the total direct forcing of anthropogenic aerosols. This biocrust control on dust cycling and its climate impacts have important implications for human health, biogeochemical cycling and the functioning of the ecosystems, and thus should be considered in the modelling, mitigation and management of global change.

Automated summary

Biological soil crusts play a significant role in stabilizing the soil surface of drylands. However, quantitative information on their impact on global dust cycling and climate effects is limited. This study reveals that biocrusts reduce global atmospheric dust emissions by approximately 60% and prevent the release of about 0.7 Pg dust per year. However, due to climate change and land-use intensification, the coverage of biocrusts is expected to be severely reduced by 2070, leading to increased dust burden and a reduction in the global radiation budget. These findings emphasize the importance of considering the control of biocrusts on dust cycling and its climate impacts in modeling, mitigation, and management of global change.