BBC World Service’s The Climate Question—stories on why we find it so hard to save our own planet, and how we might change that, spotlights how ice cores from Antarctica to Peru’s Quelccaya Ice Cap reveal both natural forcings and anthropogenic change.

Presented by Senior Broadcast Journalist Graihagh Jackson (produced by Diane Richardson), this episode features Professor Lonnie Thompson from The Ohio State University's School of Earth Sciences and Byrd Polar and Climate Research Center, and Dr. Liz Thomas, head of ice core research at the British Antarctic Survey. Together, they explain how layers within ice cores preserve evidence of historic and prehistoric fires, low-latitude microbes (bacteria, and viruses), volcanic eruptions, and shifting ocean circulation, while also capturing the rapid rise of greenhouse gases resulting from human activity. Scientists warn that as glaciers retreat, we are losing irreplaceable archives. Ice cores remain one of our most continuous records of past climate and environmental changes.

Dr. Thomas further discusses her lab's most recent analysis of the oldest continuous ice from Antarctica, the focus of the Beyond EPICA Oldest Ice project. This is the European Union's effort to seek a continuous climate record approaching 1.5 million years, extending well beyond the ~800,000-year benchmark. The objective is to sharpen our understanding of long-term carbon cycle-climate feedbacks by illuminating how Earth’s glacial cycles shifted during the mid-Pleistocene Transition and beyond, when glacial/interglacial cycles changed from a 40,000 year to a 100,000 year cyclicity.

Professor Thompson makes the case that Antarctica may not be the only place where old ice exists. Glaciers atop high mountains in far-western China may also potentially contain very old ice, although further investigation is needed.

In the context of the International Year of Glaciers’ Preservation, Professor Thompson, who just returned from a September field expedition to the Quelccaya ice cap in Peru, will return to that country where he will deliver a keynote address in Cusco at the “Mountains: Our Future,” symposium.  The symposium will be held at the Instituto Nacional de Investigación en Glaciares y Ecosistemas de Montaña's (INAIGEM’s), Peru’s National Institute of Research on Glaciers and Mountain Ecosystems. INAIGEM is a public research body attached to Peru’s Ministry of the Environment (MINAM), which is focused on glacier and mountain ecosystem research, monitoring, and risk management. 

Professor Thompson notes that although other climate proxies provide vital information, ice cores from tropical glaciers in Peru and other countries are unique archives that are unfortunately imperiled by rising temperatures, resulting in melting at the ice surface and percolation of meltwater through the porous upper layers and into crevasses, thus accelerating the melting process. The loss of these glaciers and ice caps represents not only a scientific setback, but also poses a threat to communities whose water security relies on their health.

Listen to The Climate Question on the BBC World Service.