In-phase millennial-scale glacier changes in the tropics and North Atlantic regions during the Holocene

Glaciers showed a similar evolution in Greenland, Europe, the US and the tropical Andes during the Holocene. The authors propose the Atlantic Meridional Ocean Overturning Circulation as a key driver of this trend. Based on new and published cosmic-ray exposure chronologies, we show that glacier extent in the tropical Andes and the north Atlantic regions (TANAR) varied in-phase on millennial timescales during the Holocene, distinct from other regions. Glaciers experienced an early Holocene maximum extent, followed by a strong mid-Holocene retreat and a re-advance in the late Holocene. We further explore the potential forcing of TANAR glacier variations using transient climate simulations. Since the Atlantic Meridional Overturning Circulation (AMOC) evolution is poorly represented in these transient simulations, we develop a semi-empirical model to estimate the AMOC-corrected temperature and precipitation footprint at regional scales. We show that variations in the AMOC strength during the Holocene are consistent with the observed glacier changes. Our findings highlight the need to better constrain past AMOC behavior, as it may be an important driver of TANAR glacier variations during the Holocene, superimposed on other forcing mechanisms.

Automated summary

Based on cosmic-ray exposure chronologies, the study reveals that glaciers in the tropical Andes and the north Atlantic regions showed variations on millennial timescales during the Holocene, distinct from other regions. Transient climate simulations and a semi-empirical model also suggest that the Atlantic Meridional Ocean Overturning Circulation (AMOC) plays a significant role in driving glacier changes in these regions. The findings highlight the importance of understanding past AMOC behavior as a potential driver of glacier variations.