Increased aeolian activity during climatic regime shifts as recorded in a raised bog in south-west Sweden during the past 1700 years

R. de Jong (1) , K. Schoning (2) , Siwan Björck (1)

1 Geobiosphere Science Centre
2 Department of Physical Geography and Quaternary Geology

Analyses of testate amoebae and aeolian sediment influx (ASI) were used to reconstruct effective humidity changes and aeolian activity in the coastal zone of south-west Sweden. Cores were taken from an ombrotrophic peat sequence from the Undarsmosse bog. Since both types of analysis were carried out on the same core, a direct comparison between humidity fluctuations in the bog and aeolian activity was possible, potentially providing detailed information on atmospheric circulation changes in this region. Relatively stable wet bog surface conditions occurred from 1500 to 1230 and 770 to 380 cal. yrs BP, whereas dry conditions dominated from 1630 to 1530, 1160 to 830 and 300 to 50 cal. yrs BP. The transitions between these phases occurred within 60?100 years. ASI peak events were reconstructed around 1450, 1150, 850 and after 370 cal. yrs BP. Most interestingly, these aeolian activity peaks started during the recorded hydrological transitions, regardless of the direction of these shifts. Our results therefore suggest that climatic regime shifts in this region were associated with temporary intensifications of atmospheric circulation during the past 1700 years. Several ASI peaks apparently coincide with reduced solar activity, possibly suggesting a solar related cause for some of the observed events.

Domaines: Interfaces continentales, environnement; Sciences de la Terre

R. de Jong, K. Schoning, Siwan Björck. Increased aeolian activity during climatic regime shifts as recorded in a raised bog in south-west Sweden during the past 1700 years. Climate of the Past Discussions, 2007, 3 (1), pp.383-408. ⟨hal-00298178⟩