El Niño and human history: The record written in tropical glaciers

What role does environment play in human history? We know about earthquakes, floods and similar catastrophes, but the influences of global climate on human civilization are harder to tease from the evidence. In 2013, Lonnie Thompson and Ellen Mosley-Thompson announced an analysis of two tropical ice cores drilled from Peru's Quelccaya Ice Cap. This record, which they called a “Rosetta Stone” of climate history, was so detailed that they could discern annual variations in temperature, precipitation and atmospheric chemistry over the past 14 centuries. They are now examining the interplay among doughts, El Niño oscillations and human history associated with the unusual events recorded at Quelccaya and a glacier atop the Himalayas. These cores contain evidence of “Black Swan” events corresponding to devastating population disruptions that may have been climate-related. Understanding the characteristics and causes of such events is critical for design adaptive measures in a world with unprecedented population and anthropogenic influences on climate.

For supplemental information about this New Horizons in Science briefing, see the CASW website