Enhanced phosphorus weathering contributed to Late Miocene cooling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39875402.
- Also identified by DOI 10.1038/s41467-025-56477-7 and PMC identifier 11775330.
- Licence recorded as CC BY-NC-ND.
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Abstract
Late Miocene climate evolution provides an opportunity to assess Earth's climate sensitivity to carbon cycle perturbation under warmer-than-modern conditions. Despite its relevance for understanding the climate system, the driving mechanisms underlying profound climate and carbon cycle changes - including the enigmatic Late Miocene cooling from 7 to 5.4 million years ago - remain unclear. Here, we present magnetic and geochemical paleoceanographic proxies from a hydrogenetic ferromanganese crust retrieved in the northwestern Pacific Ocean. Our results indicate a striking 50% surge in deep ocean phosphorus concentrations occurred 7 - 4 million years ago, synchronous with enhanced deep ocean oxygen consumption. Employing a global biogeochemical model, we show that increased continental phosphorus weathering, without a concurrent rise in silicate weathering, contributed to the decline in atmospheric CO<sub>2</sub> and associated cooling over the Late Miocene. This suggests a prominent decoupling of phosphorus and silicate weathering during a major carbon cycling event over the last 10 million years.