Beyond EPICA – Oldest Ice Core: Insights from a 1.2-Million-Year-Old Climate Record

The Beyond EPICA – Oldest Ice project in East Antarctica marks a groundbreaking milestone in unraveling Earth’s past climate dynamics. Recent findings confirm that the paleoclimatic record extends back at least 1.2 million years, offering unprecedented opportunities to explore glacial-interglacial cycles and the mechanisms driving Earth’s climate system.

To better constrain the long-term response of Earth’s climate system to continuing greenhouse gas emissions, it is essential to turn to the past. A key advance would be to understand the shift in Earth’s climate response to orbital forcing during the 'Mid-Pleistocene transition' [MPT, 900,000 (900 kyr) to 1.2 million years (1.2 Myr) ago], when a dominant 40 kyr cyclicity gave way to the current 100 kyr period. It is critical to understand the role of forcing factors and especially of greenhouse gases in this transition. Unravelling such key linkages between the carbon cycle, ice sheets, atmosphere and ocean behaviour is vital, assisting society to design an effective mitigation and adaptation strategy for climate change. Only ice cores contain direct and quantitative information about past climate forcing and atmospheric responses.

Drilling operations reached the bedrock at a depth of 2800 meters, granting access to ancient ice. High-resolution analyses of hydrogen isotopes (δD) were conducted, with sampling resolutions down to 25 cm, providing unparalleled insights into climate and environmental fluctuations. Concurrently, dielectric profiling (DEP) measurements were employed to identify detailed climatic stratifications within the ice core.

This presentation will highlight the main results achieved so far, emphasizing their implications for understanding the transition of glacial cycles from 40,000 to 100,000 years and the long-term evolution of greenhouse gas concentrations. These findings lay the foundation for subsequent talks in this session, which will delve into isotopic, chemical, and physical analyses of the ice core.

By bridging critical gaps in our knowledge of paleoclimate, this work also establishes a robust basis for modeling future climate scenarios, reinforcing the importance of understanding Earth’s climatic past to inform predictions of its future.