Changing Seasons: An Effect of the North Atlantic Oscillation?

Abstract

Changes in spring phenology at mid- and high latitudes have shown an association with fluctuations of winter surface temperature, with the warmer winters being generally followed by early onsets of the growing season. The study of the interannual variability of timing and length of the growing season is gaining importance because plant phenology is a sensitive indicator of climate change and has broad impacts on terrestrial ecosystems through changes in productivity and in the annual carbon and water cycles. The dependence between onset of the spring season (measured through dates of first leafing, blooming, pollen season start, and ice break in lakes) in Europe and the phases of the North Atlantic Oscillation, a large-scale displacement of air mass between the subarctic and the subtropical regions of the North Atlantic, has been studied in detail. The effects of this oscillation include climatic anomalies in the months preceding the onset of the Northern Hemisphere growing season, with important impacts on spring phenology.