Precession and obliquity forcing of the freshwater budget over the Mediterranean

20 November 2013, 4.00 PM - 20 November 2013, 4.00 PM

Peel Lecture Theatre, Geographical Sciences, University Road, Bristol, BS8 1SS

Joyce Bosmans from the University of Utrecht (chaired by Rachel Flecker and Alice Marzocchi)

The response of Mediterranean climate to orbital forcing is a heavily debated topic in paleoclimatology. Evidence from pollen records, speleothem oxygen isotopes and sedimentary sequences suggests that during times of minimum precession, i.e. increased insolation seasonality, the Mediterranean area was wetter and the Mediterranean sea surface was fresher. Also, there is an obliquity signal in the Mediterranean records secondary to the main precession cyclicity. The main source for freshening of the sea surface is thought to be increased Nile runoff, as a consequence of a strengthened North-African monsoon, but precipitation over the Mediterranean Sea itself may have also played a role. In this talk Joyce will discuss the results of climate model experiments with separate precession and obliquity forcing. These were performed with the high-resolution general circulation model EC-Earth. The relative roles of precipitation, evaporation and runoff will be discussed for both precession and obliquity, in order to investigate whether changes in the Mediterranean freshwater budget are mainly driven by (monsoonal) runoff or local precipitation changes.

This event is free and open to all.

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