A new paper with free pdf:
Earthâs orbital variations on timescales of 10^4-10^5 years, known as Milankovitch cycles, have played a critical role in pacing climate change and ecosystem dynamics, through glacial and/or monsoon dynamics. However, the climatic and biotic consequences of these cycles on much longer (~â10^7 years) timescales remain unclear, due to a lack of long proxy records with precise age constraints. Here, we showâ~â10-Myr scale variations in early Mesozoic (250â180 Ma) records of lake-level, desert distribution, biogenic-silica burial flux, atmospheric CO2 levels (pCO2), and sea-surface-temperature (SST). Their phase relationships, coupled with carbon cycle modeling results, suggest that orbitally-paced summer monsoon dynamics modulates changes in terrestrial weatherability byâ~â20%, affecting changes in pCO2 of up to 500â1,000 ppmv and 3â7 ÂC SST. We also infer that theseâ~â10-Myr scale climatic variations could have been causally linked to biotic turnover, size variations in dinosaur footprints, and tetrapod dispersal, potentially through spatio-temporal variations in resource availability and arid-hot climatic barriers at low-middle latitudes.
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