Of course the politically correct verbiage is "climate change."
Between the 13th and 11th centuries BCE, most Greek Bronze Age Palatial centers were destroyed and/or abandoned throughout the Near East and Aegean, says this paper by Brandon L. Drake
A sharp increase in Northern Hemisphere temperatures preceded the wide-spread systems collapse, while a sharp decrease in temperatures occurred during their abandonment. (Neither of which, I am sure - the increase or the decrease - were caused by humans.)
Mediterranean Sea surface temperatures cooled rapidly during the Late Bronze Age, limiting freshwater flux into the atmosphere and thus reducing precipitation over land, says Drake, of the Department of Anthropology, University of New Mexico.
This cooling and ensuing aridity could have affected areas that were dependent upon high levels of agricultural productivity. The resulting crop declines would have made higher-density populations unsustainable.
Indeed, studies of data from the Mediterranean indicate that the Early Iron Age was more arid than the preceding Bronze Age. The prolonged arid conditions - a centuries-long megadrought, if you will - lasted until the Roman Warm Period.
Comment: Speaking of 'collapse of civilization', read Laura Knight-Jadczyk's latest research
Comets and the Horns of Moses (The Secret History of the World) for a more enlightened study of civilization's recurring collapses.