Mineral dust and the global critical zone

The Critical Zone (CZ) has been conceptualized as a vertically stratified “weathering reactor,” studied intensively through local observatories and spatially restricted sites. While this reductionist approach has yielded fundamental insights, it risks overlooking the broader spatial and temporal dynamics of the CZ. Here I argue for a reframing of CZ science to embrace its true multi-dimensional nature, emphasizing horizontal landscape connectivity and deep-time legacies. Using mineral dust deposition in mountain environments as a central example, I illustrate how far-traveled atmospheric inputs shape soil formation, nutrient cycling, and CZ function. These connections reveal mountain soils as products of fluxes originating in distant source regions, underscoring the limitations of strictly site-based conceptual frameworks. Additional fluxes, for instance water vapor, microbes, nutrients, and sediment, likewise link the CZ across space and time. To advance CZ science, I suggest 1) the use of “Global Critical Zone” to distinguish the planetary-scale CZ from the local CZ, 2) an updated conceptual diagram to depict how interconnected local CZs comprise the Global CZ, and 3) increased international coordination among CZ and related research networks to aid our understanding of the whole. Embracing a landscape-mantling, temporally integrated perspective is essential for elucidating CZ evolution, forecasting global change impacts, and aligning site-based studies with the Earth system processes that collectively shape the CZ at the planetary scale. • CZ science needs to upscale from the local to the global • Mineral dust transport links distant parts of the Critical Zone • Global Critical Zone could be used when referring to the planetary-scale CZ • A new diagram could be adopted to emphasize the Global CZ • Increased international coordination among CZ research networks would aid understanding of the Global CZ