The varying sun and its influence on our climate is one of the most controversially discussed topics in climate research. Radionuclide records and the comparison with past climate changes can help to understand the influence of the sun on the climate.

The cosmogenic radionuclides (as e.g. 10Be, 14C, 36Cl) are produced in the atmosphere by cosmic ray particles. Depending on the helio- and geomagnetic field the cosmic rays are more or less shielded from the Earth's atmosphere. The comparison of different radionuclide records allows us to correct for influences of the radionuclide systems and to isolate the common production signal to obtain a reliable estimate of past changes in solar activity.

By comparing radionuclide records with geomagnetic field reconstructions and climate records I am addressing the following questions:

1. To what extent are the variation in the cosmogenic radionuclide records caused by changes in solar activity? What is the contribution of geomagnetic field induced changes in the radionuclide records?

2. Can observed climate variations be related to changes in solar activity and are there mechanisms that can explain the relationship between climate and solar activity variations?

3. Is it possible to infer past changes in the carbon cycle by comparing 10Be and 36Cl records from ice cores with reconstructions of the past atmospheric 14C concentration?

3. How can we best reconstruct "Paleo Space Climate"? This involves the reconstruction of past solar storms that only recently have been discovered