Last millennium climate change in the occupation and abandonment of Palau's Rock Islands

The role of AD 1300 climate change in widespread societal change in Palau and the Pacific Basin has recently been debated by Fitzpatrick (2010, 2011) and Nunn and Hunter-Anderson (2011). The central proposition examined here is the link between a sealevel driven food crisis and the outbreak of conflict, which is hypothesized in the AD 1300 event model to have led people to shift from unprotected coastal parts of large islands (e.g. volcanic Babeldaob) to more readily defensible offshore islands (e.g. limestone 'Rock Islands') during the transition between the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Revision of radiocarbon dates from village sites in the Rock Islands suggests instead that permanent settlements were established on small offshore islands during the MWP with village abandonment during the LIA. Palaeoclimate records from equatorial islands show that during the LIA Palau had less rainfall from the southward movement of the Intertropical Convergence Zone (ITCZ). The abandonment of multiple limestone islands by a population estimated at 4000-6000 people may have been influenced by decreased precipitation and more tentatively from a decline in near-shore marine foods as a result of sea-level fall.