Instrumental records of mean annual temperature extend back to the
seventeenth and eighteenth centuries at multiple sites in Europe. For
such long time series, we expect histograms of mean annual temperature
data to become skewed towards higher temperatures with time because of
global warming. This occurs, but at 15 of 17 sites, we find that
skewness changed abruptly and started increasing rapidly between 1982
and 1993. We argue that this finding may imply an abrupt change in the
climate system affecting Europe at that time. One possible cause is a
climate tipping point having been passed. Of known tipping elements, we
find Arctic sea loss, potentially linked to reduced sulfate aerosol
emissions, and coupled to temperature by an albedo or some other
feedback mechanism, a likely candidate. This is based on good
correlations of sea ice extent and sulfate aerosol emissions with
skewness of mean annual temperature data.