An abrupt cooling event in Europe about 2,800 years ago was linked to a sustained reduction in solar radiation, reports a study published online this week in Nature Geoscience. The finding indicates that solar forcing may influence European climate over long, as well as short, timescales.
Shifts in solar activity influence climate on a decadal timescale, but evidence for a link on longer timescales has been lacking. Celia Martin-Puertas and colleagues analysed lake sediments from Germany to determine annual variations in windiness and solar activity between 3,300 and 2,000 years ago. They observed a sharp reduction in solar radiation and a related shift in windiness around 2,800 years ago. Using climate models, they suggest that the reduction in solar activity altered atmospheric circulation, leading to intensified windiness and a cooling in Europe.