Paper Reviewed
Czymzik, M., Muscheler, R. and Brauer, A. 2016. Solar modulation of flood frequency in central Europe during spring and summer on inter-annual to multi-centennial timescales. Climate of the Past 12: 799-805.

According to Czymzik et al. (2016), "solar influences on climate variability are one of the most controversially discussed topics in climate research." And thus intrigued by this state of affairs, they go on to describe how they analyzed "solar forcing of flood frequency in central Europe during spring and summer on inter-annual to multi-centennial timescales," based on their study of daily discharge data of southern Germany's River Ammer back to AD 1926 (which encompassed solar cycles 16-23), along with the 5500-year flood-layer record they derived from analyses of varved sediments of the downstream Ammersee River. And what did they learn by so doing?

The three researchers discovered that flood frequency in both records is significantly correlated to changes in two types of solar activity," namely, (1) "the solar Schwabe cycle" and (2) "multi-centennial oscillations." And they thus further conclude that (3) "the unexpected direct response of variations in River Ammer flood frequency to changes in solar activity might suggest that the solar top-down mechanism is of particular relevance for hydroclimate extremes." Given such findings, there should be little, if any, controversy with regard to a solar influence on flooding in southern Germany!