ice age
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.

Those four centuries - known as the 'Greek Dark Ages' - were typified by low population levels, rural settlements, population migration, and limited long-distance trade.

The Late Bronze Age collapse is associated with the loss of writing systems such as Linear B, and the extinction of Hatti as both a written and spoken language. Writing and literacy do not return to the Aegean until the end of the 'Greek Dark Ages' in 8th century BCE with the spread of the Phoenecian alphabet.

The collapse of Palatial Civilization occurred in different places at different times. Many of these destructions have been attributed to human-causes. (We love to blame humans for climate-driven circumstances, don't we?) Large population migrations took place, most famously with the incursions of the 'Sea Peoples' into the Nile Delta and the Levant.

In Egypt, several inscriptions detailed wars with 'Sea People' beginning in the reign of Ramses II (1279-1213 BCE). While population movements of the 'Sea People' were better documented in Egypt and the Levant, they have been tied to destabilization of the Aegean region as well.

The ensuing economic decline resulted in the widespread dissolution of governments. Once the governments were dissolved it was impossible to reestablish a central authority.

While economic collapse continues to be the dominant theory for the collapse of Palatial Civilization in the Bronze Age, climatic/environmental explanations have also been proposed. (I think the climate conditions triggered the economic collapse, of course.)

Conditions improve following the introduction of iron tools, and accelerate at the beginning of the Roman Warm Period at 350 BCE, says Drake.
Wouldn't this make it appear that warmer climates are good for civilization? And that cooler climates can lead to systems collapse?

I'm thinking that our leaders are sorely mislead.
See all of Drake's paper, including citations.