Evidence for a link between the flux of galactic cosmic rays and Earth's climate during the past 200,000 years

The possibility that galactic cosmic rays (GCR) influence the Earth's cloud cover and therefore have an important impact on the Earth's radiative climate forcing has become a leading candidate to explain the observed sun-climate connection. A correlation between GCR and low cloud cover has been ascertained in models and observations over the past few years. The deposition of cosmogenic radionuclides in ice cores and deep sea sediments can be used as a proxy for the past GCR-flux and provides an important tool to study the supposed GCR-climate connection on glacial-interglacial timescales. In this study, a record of geomagnetic paleointensity based on Be-10 from deep sea sediments is used as proxy for GCR-flux over the past 200,000 years. It is compared with climate records from marine, terrestrial and ice core archives. Our results are consistent with the GCR-climate theory and suggest the existence of a GCR-climate connection over the past 200,000 years. (C) 2004 Elsevier Ltd. All rights reserved.