Long term context for recent drought in northwestern Africa

Abstract

Anthropogenic climate change is projected to exacerbate midlatitude aridity. Here, we analyze newly developed multi‐century tree‐ring records for a long‐term perspective on drought in Tunisia and Algeria. We use a new set of 13 Cedrus atlantica and Pinus halepensis chronologies with a strong signal for warm‐season drought (May–August) to generate a robust, well‐validated reconstruction of the Palmer Drought Severity Index (PDSI) for the period AD 1456–2002. Key features of the reconstruction reveal the magnitude of pre‐instrumental droughts from the historic record. Remarkably, the most recent drought (1999–2002) appears to be the worst since at least the middle of the 15th century. This drought is consistent with the early signature of a transition to more arid midlatitude conditions, as projected by general circulation models.