Change points and temporal dependence in reconstructions of annual temperature: Did Europe experience a Little Ice Age?

TL;DR

This study investigates whether the Little Ice Age in Europe was characterized by significant climate shifts or if observed cooling was due to random variability and data smoothing effects, challenging previous assumptions.

Contribution

The paper provides evidence that European temperature variations during the Little Ice Age are consistent with random fluctuations rather than structural climate changes.

Findings

No significant temporal dependence or structural breaks found in temperature data.

Observed cooling may be an artifact of data smoothing (Slutsky effect).

European climate variability during the period resembles white noise.

Abstract

We analyze the timing and extent of Northern European temperature falls during the Little Ice Age, using standard temperature reconstructions. However, we can find little evidence of temporal dependence or structural breaks in European weather before the twentieth century. Instead, European weather between the fifteenth and nineteenth centuries resembles uncorrelated draws from a distribution with a constant mean (although there are occasional decades of markedly lower summer temperature) and variance, with the same behavior holding more tentatively back to the twelfth century. Our results suggest that observed conditions during the Little Ice Age in Northern Europe are consistent with random climate variability. The existing consensus about apparent cold conditions may stem in part from a Slutsky effect, where smoothing data gives the spurious appearance of irregular oscillations when the underlying time series is white noise.