Tracking deep-time environmental stability exposes a global conservation gap

Continents drift across latitudinal climate zones that are themselves shifting as Earth's climate evolves [1-5]. The relative speed of these two motions (tectonic versus climatic velocity) determines how much climate change a given landmass experiences over geological time: where plates and climate zones move in concert, local climates can remain stable for millions of years, allowing lineages to persist and diversify. However, whether this interplay has shaped deep-time environmental stability and, in turn, present-day biodiversity patterns remains untested. Here, using a Lagrangian framework to track land parcels through 60 million years of palaeogeographic, palaeoclimatic, and palaeoproductivity reconstructions, we show that in amphibians, reptiles, birds, and mammals, species richness increases with the time a parcel has spent within a stable environmental envelope. This accumulation shows no sign of saturation, instead accelerating across nearly all combinations of taxonomic group and environment. Integrating stability along tectonic trajectories identifies modern macroevolutionary refugia (>20 Myr of cumulative stability). Of these refugia, 77.9% lack legal protection---rising to 91.5% in Asia---and just 2.1% fall within strictly protected areas. Refugia are only modestly better protected than unstable land (22.1% versus 15.8%), with over three-quarters of this difference driven by the weakest protection tiers. Having assembled while their environments moved at centimetres to metres per year, these biotas face present-day climate velocities of hundreds of metres to kilometres per year [6, 7], a kinematic debt that protecting static coordinates alone cannot address.