Our next Marine Ecology and Climate meeting will discuss the paper by van Sebille et al. (2015) on “Ocean currents generate large footprints in marine palaeoclimate proxies”. This work tries to assess the effect of ocean currents on sinking particles using a high resolution ocean model. This is particularly relevant for the interpretation of paleoproxy of water column conditions (here taking the foram proxy example), where the currents could move particles up to 1000 km horizontally.

This meeting is only open to University of Bristol staff and students.

Abstract

Fossils of marine microorganisms such as planktic foraminifera are among the cornerstones of palaeoclimatological studies. It is often assumed that the proxies derived from their shells represent ocean conditions above the location where they were deposited. Planktic foraminifera, however, are carried by ocean currents and, depending on the life traits of the species, potentially incorporate distant ocean conditions. Here we use high-resolution ocean models to assess the footprint of planktic foraminifera and validate our method with proxy analyses from two locations. Results show that foraminifera, and thus recorded palaeoclimatic conditions, may originate from areas up to several thousands of kilometres away, reflecting an ocean state significantly different from the core site. In the eastern equatorial regions and the western boundary current extensions, the offset may reach 1.5 C for species living for a month and 3.0 C for longer-living species. Oceanic transport hence appears to be a crucial aspect in the interpretation of proxy signals.