Climate velocities and species tracking in global mountain regions

Mountain ranges harbor high concentrations of endemic species and are indispensable refugia for lowland species under anthropogenic climate change1,2. Forecasting biodiversity redistribution hinges on assessing whether species can track shifting isotherms as climate warms3,4. However, a global analysis of isotherm shift velocities along elevation gradients is hindered by the scarcity of weather stations in mountainous regions5. We address this by mapping the lapse rate of temperature (LRT) across mountain regions globally using satellite data (SLRT) and laws of thermodynamics to account for water vapour6 (i.e., the moist adiabatic lapse rate: MALRT). Dividing the rate of surface warming from 1971 to 2020 by either the SLRT or MALRT, we provide the first maps of vertical isotherm shift velocities. We identify 17 mountain regions with exceptionally high vertical isotherm shift velocities (> 11.67 m/yr for the SLRT, > 8.25 m/yr for the MALRT), predominantly in dry areas but also in wet regions with shallow lapse rates like Northern Sumatra, the Brazilian Highlands, and Southern Africa. By linking these velocities to species range shift velocities, we report instances of close tracking in mountains with lower climate velocities. However, many species lag behind, suggesting persisting range shift dynamics even if we manage to curb climate change trajectories. Our findings are vital for devising global conservation strategies, particularly in the 17 high-velocity mountain regions we identified. References Rahbek, C. et al. Building mountain biodiversity: Geological and evolutionary processes. Science 365, 1114-1119 (2019). Rahbek, C. et al. Humboldt's enigma: What causes global patterns of mountain biodiversity? Science 365, 1108-1113 (2019). Chen, I. C., Hill, J. K., Ohlemuller, R., Roy, D. B. & Thomas, C. D. Rapid Range Shifts of Species Associated with High Levels of Climate Warming. Science 333, 1024-1026 (2011). Lenoir, J. et al. Species better track climate warming in the oceans than on land. Nature Ecology & Evolution, 1-16 (2020). Pepin, N. et al. Elevation-dependent warming in mountain regions of the world. Nat Clim Change 5, 424-430 (2015). Holton, J. R. & Hakim, G. J. An introduction to dynamic meteorology. Vol. 88 (Academic press, 2012).