Map showing glacier extent and graphs
Mapped extent of a small glacier (purple shading) that occupied a cirque in north-west Scotland during the end of the last ice age, showing the distribution of glacial landforms and of the erratic boulders used to build this terrestrial climate record. Ages for specific glacier extents were deduced via cosmogenic beryllium-10 surface-exposure dating and are shown in the left-hand panels in thousands of years before present. These data show that the glacier advance culminated prior to the Younger Dryas and that deglaciation occurred during the stadial. Credit: Bromley et al. [2023], Figure 2
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Journal of Geophysical Research: Earth Surface

The weakening of North Atlantic currents by vast amounts of fresh water (solid or liquid) released rapidly from the Laurentide and other ice sheets has been held as the culprit of a rapid cooling of northern Europe for many decades. It was traditionally thought that glaciers expanded during the Younger Dryas, the last of such cooling events.

In a new study, Bromley et al. [2023] challenge this view. The authors mapped deposits of relict glaciers in Scotland and, by using cosmogenic nuclide geochronology, established that the last glaciation in Scotland terminated prior to the Younger Dryas stadial, and in some places, disappeared during this cooling period. These results suggest that, similar to other parts of the world, Scotland experienced warming summers during the Younger Dryas stadial despite the severe winter cooling. These results are in conflict with the current paradigm as they indicate that Scottish glaciers retreated during the period of weakened North Atlantic circulation. The authors argue that this key region is characterized by strong seasonality during stadial events and that the traditional proxies register primarily cold winter anomalies.

Citation: Bromley, G., Putnam, A., Hall, B., Rademaker, K., Thomas, H., Balter-Kennedy, A., et al. (2023). Lateglacial shifts in seasonality reconcile conflicting North Atlantic temperature signals. Journal of Geophysical Research: Earth Surface, 128, e2022JF006951. https://doi.org/10.1029/2022JF006951

—Olga Sergienko, Editor, JGR: Earth Surface

Text © 2023. The authors. CC BY-NC-ND 3.0
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