Variability and extremes of northern Scandinavian summer temperatures over the
past two millennia"The record provides evidence for substantial
warmth during Roman and Medieval times, larger in extent and longer in duration than 20th century
warmth."
"Our results showed that introducing an improved temperature reconstruction
does not automatically clarify climate history in a given
region. In northern Scandinavia, we now arrive at a situation where a
number of high-resolution proxy records – all passing classical calibration
and verification tests – are available within a confined region
that is characterized by homogeneous temperature patterns. These
records, however, differ by several degrees Celsius over the past
two millennia, which appears huge if compared with the 20th Century
warming signal in Scandinavia or elsewhere. We conclude that the
temperature history of the last millennium is much less understood
than often suggested, and that the regional and particularly the hemispheric
scale pre-1400 temperature variance is largely unknown."