10Be has been measured in a 300 m long ice core from Greenland. After a general analysis of the 10Be data the potential and the limitations of 10Be records in ice to reconstruct solar variability are discussed. Special emphasis is given to periods of low solar activity (Maunder Minimum etc.). The ‘clock problem’ is addressed, also the question whether the Schwabe cycle maintains its phase. Finally the question of what 10Be can tell us about changes of the solar irradiance in the past is explored.

The atmospheric production rate of the cosmogenic isotope 10Be is modulated by the solar wind. Spectral analysis of a 560 year long 10Be concentration record from a Greenland ice core shows that this modulation process was active at all times even during quiet sun periods (Maunder minimum). To separate production effects from the effects of transport and deposition processes, three 10Be records of different length and time resolution were used to calculate the expected 14C variations.Comparisons with measured 14C variations show that during the Holocene, for time scales larger than 3 years, the mixing and transport processes played only a minor role. Measurements of these isotopes in terrestrial archives therefore provide information about past solar variability.Satellite measurements reveal a positive relationship between solar activity and solar irradiance. Comparisons between 10Be in polar ice samples and 14C in tree rings with temperature records show common features which confirm this relationship over the last few centuries.