Carbon cycle and solar changes at the end of the last Ice Age
The transition period at the end of the last Ice Age was characterized by a long term warming trend which was interrupted by several strong cold and warm pulses. This highly variable climate also affected the cycling of CO2. By altering the exchange rates with and within the largest carbon reservoir, the ocean, the whole carbon cycle did undergo relatively large and frequent changes. Additionally, an altered ocean ventilation means also a shift in the heat exchange between ocean and atmosphere. This in response influences climate and thus, is a so-called "feedback effect". However, the constraints of these interactions are still barely known. Our project addresses solar variations and carbon cycle changes at the end of the last Ice Age.
A simplified scheme of our approach to investigate the global carbon cycle, its influential factors, and accessible archives for this purpose is given in figure 1. We use a rare isotope of the carbon atom, radiocarbon or 14C, as a tracer for the speed of exchanges processes in the carbon cycle. We access the ancient 14C concentrations by investigating "archives" like tree rings, sea sediments, or corals (Fig. 1). The isotope Beryllium-10 (10Be), was measured in ice cores, and is used for comparison. Both isotopes are formed in the upper atmosphere and their production rates mainly depend on solar activity and geomagnetic changes.
However, 10Be does not enter the carbon cycle but is preserved in ice cores subsequently (Fig. 1). Since their formation is similar, differences of 10Be and 14C records are thus, most likely related to the carbon cycle. Moreover, temporal changes in these differences are indicators of changes in carbon cycling. We are trying to identify and characterize these periods of changing solar activity and carbon cycle dynamics at the end of the last Ice Age.
Investigating periods of strong climate changes that have not been influenced by anthropogenic factors helps us to improve the understanding of the climate system. In particular, it provides estimates of the natural climate variability. Our project will ameliorate the constraints of innate carbon cycle dynamics, and thus, advance the perception of modern anthropogenic impacts.