|Sunrise over Athens, Greece|
They published 2 papers on the subject in the journal European Geophysical Union (EGU) , .
According to the 2 scientists, climate is often cyclic. The first study appeared in February 2013 and it examined six of the longest existing thermometer data series recorded in Europe, as well as one dataset from an Antarctic ice core and another from a data series extracted from stalagmites. The datasets were covered the period of 1757 – 2010.