ABSTRACT
Overall, the impression gleaned from several centuries prior to 1100 is of the resilience of Mediterranean economies in the face of what could be critical climate changes, especially as regards the water balance. Witness the boom in Islamic/Christian long-distance trade as the eleventh century drew towards its close, notably as between the western basin and the Near East.139 One factor in this development may have been the migratory rainbelt discerned by Claudio Vita-Finzi. Another was the way topography presented alternatives. Take viticulture. The extension northwards, in high medieval times, of the bounds of vine cultivation in north-west Europe seems not to have been offset by any general retraction geographically within its Mediterranean heartlands. For one thing, a displacement of one or two hundred metres on a steep mountainside can transpose the grape to a quite different mesoclimate, certainly as regards warmth and sunlight.140 In other words, the margins of cultivation may shift in the vertical more readily than in the horizontal.
