Late eocene uplift and erosion of eastern tibet initiated long-term cenozoic global cooling

Global cooling beginning ∼50 million years ago is commonly attributed to atmospheric CO2 drawdown driven by silicate weathering during uplift of the Tibetan Plateau and Himalaya. Yet direct, well-dated evidence connecting surface rise to cooling remains scarce. New paleoelevation and paleoenvironment data from the Mangkang Basin, Eastern Tibet, constrained by radiometrically anchored magnetostratigraphy and cyclostratigraphy, show rapid uplift from 3.3 ± 0.9 km to 4.3 ± 0.9 km with ∼5°C regional cooling between 35.7 and 35.2 Ma. Thus, Eastern Tibet attained near-modern elevations prior to the Eocene–Oligocene transition (EOT, 33.9 Ma), and long before major Himalayan uplift. This uplift is temporally correlated with increased orographic rainfall, initiation of Asia’s major rivers, enhanced sediment flux to marginal seas, and rising oceanic 87Sr/86Sr ratios. We suggest that late Eocene uplift and erosion of Eastern Tibet—not the later Miocene Himalaya uplift or plateau-wide rise—may have played an important role in driving the long-term CO2 decline and global cooling that ultimately culminated in the EOT.