At the midpoint of the transition at around 900 ka (the "900 ka event"), observations of a globally synchronous decrease in benthic Î♁3C suggest a large-scale perturbation to the oceanic carbon cycle. The Mid-Pleistocene Transition (MPT) was a profound reorganization of the climate system between 0.8 to 1.2 million years ago (Ma) that led to the establishment of 100 thousand year (kyr)-paced glacial cycles. The deep ocean circulation reconstructions resulting from this project will add a new dimension to the PRISM effort and will be useful for both initialization and evaluation of future model simulations.Īssessing Deep Ocean Carbon Storage Across the Mid-Pleistocene Transition Here, we present early results from a new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene, using Î♁3C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic imprint on fossil fish teeth as a proxy for water mass source region along a three-site depth transect from the Walvis Ridge (subtropical South Atlantic). However deep ocean temperature is not a conclusive proxy for water mass, and most coupled model simulations predict transient decreases in North Atlantic Deep Water production in 21st century, presenting a contrasting picture of future warmer worlds.
Ongoing sea surface and deep ocean temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm anomaly coupled with increased evaporation in the mid-Pliocene, possibly driving enhanced meridional overturning circulation and North Atlantic Deep Water production. The mid-Pliocene (3.264 - 3.025 Ma) is the most recent interval in Earth's history with sustained global temperatures in the range of warming predicted for the 21st century, providing an appealing analog with which to examine the Earth system changes we might encounter in the coming century.
A new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene
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