The Sun is the main energy source of Earth’s climate system. Total solar irradiance varies by ~1 W m^-2 throughout the 11-year solar ‘Schwabe’ cycle. Regardless of this small energetic change, numerous observations, paleoclimate reconstructions and climate model results point to substantial solar influences on climate, on time-scales from years to millennia, modified by a complex interplay of climate forcings and boundary conditions. Despite the diversity of information, a comprehensive understanding of Sun-climate linkages is still limited. Main cause is the nearly exclusive limitation of existing Sun-climate studies to the climatologically comparably stable Holocene.

Cosmogenic radionuclides like ¹⁰Be and ¹⁴C are produced in Earth’s upper atmosphere by incident galactic cosmic rays. The production rate of these isotopes is, in turn, modified by varying solar and geomagnetic shielding of galactic cosmic rays. Therefore, deposited in natural environmental archives, ¹⁰Be and ¹⁴C provide proxy records of both solar variability and Earth’s magnetic field strength.

During the recent decades cosmogenic radionuclide records were routinely measured from trees and ice cores.  However, these archives do not carry a paleomagnetic signal, adding uncertainty to existing solar variability reconstructions. Moreover, well-dated ¹⁴C records from trees are limited to the last 14000 years and ice core ¹⁰Be time-series lose temporal resolution back in time due to lateral ice flow. Sediment records can provide independent records of both, ¹⁰Be production and geomagnetic field strength far into the distant past, without losing temporal resolution.

Within this proposal, we aim at establishing novel proxy records of solar variability applying paired ¹⁰Be and paleointensity measurements from Black Sea sediments at 40-year resolution for parts of the last and penultimate glacial. We will provide the first ¹⁰Be records from marine sediments at a sufficient resolution for sub-centennial solar variability reconstruction. A multi-layer (and multi-radionuclide record) approach will allow us to distinguish solar from geomagnetic and environmental effects on ¹⁰Be deposition.

Ultimate goal of the research is the investigation of solar influences on climate during full Last Glacial Maximum conditions (22-28 ka BP), a period of distinct Dansgaard-Oeschger variability (40-55 ka BP) and Termination II (128-134 ka BP), based on systematic comparisons of our novel solar variability records with paleoclimate time-series directly from Black Sea sediments and from around the globe. The work will improve our knowledge about spatial and temporal patterns of Sun-climate linkages and allow us to better anticipate Sun’s role within anthropogenic 21^st century climate change.