Proxy Development

Biomarker-based sea ice recontrsuctions. (Photo: Alfred-Wegener-Institut)

The era of instrumental weather measurements spans only a tiny fraction (<150 years) of Earth’s climate history and thus provides an inadequate perspective of its climate variability and mechanisms. To reconstruct past climate variability for times prior to the era of instrumental measurements, marine geologists have to rely on indirect evidence – on information provided by “proxies”, which stand as surrogates for particular climate variables. The analysis of proxies offers the potential to reconstruct an array of parameters (e.g., temperature, sea ice cover, global ice volume, nutrients, marine biological productivity, etc.), which responded to or modulated regional and global changes in the climate system.

One of our major efforts is to improve and extend the currently sparse library of quantitative proxies in polar latitudes. In this context we focus on reconstructing:

  • Upper ocean temperatures using biomarkers, diatom assemblages
  • Sea ice reconstructions with diatom assemblages and biomarkers
  • Nutrient utilization through phytoplankton measuring Si isotopes in biogenic opal
  • Upper ocean salinity through measuring oxygen isotopes in diatoms.
Schematic overview of stratigraphic methods and proxies for reconstruction of ocean and atmosphere environmental parameters and their applicability in different types of sediment typically find in polar oceans.