This is the first part of a two-part study to construct a vegetation map around the Mediterranean Sea that is an accurate representation of conditions two millennia ago, and to use this data in general circulation model experiments to better understand historical climate and climate change. Particularly, we want to evaluate the sensitivity of the atmospheric circulation around the Mediterranean Sea to changed land surface conditions. The idea that 2000 yBP, during the Roman Classical Period (RCP), northern Africa and the Mediterranean countries were moister than today is widely acknowledged but has not been discussed within a scientific framework until a few decades ago.
Archeological and historical documents provide some qualitative agreement that moister conditions prevailed during Roman times, and interdisciplinary scientific research provides some confidence through proxies that the Mediterranean has been experiencing a trend towards drier conditions.
The first step of this work is the multidisciplinary task of organizing all the available information coming from historical and archeological sources, together with what is known from scientific methods, into a coherent history of climate and vegetation. The second step is to run a 25 year GCM experiment, with a forcing that represents an idealized RCP vegetation distribution. The forcing produces a noticeable effect on the climate, namely a northward shift of the intertropical convergence zone during summer over the African continent.
Complete copies of this report are available from:
Center for Ocean-Land-Atmosphere Studies
last update: 23 December 1998
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