Was the Little Ice Age global? The cosmogenic perspective

Unlike other glacier fluctuations during the Holocene, the glacier advances during the Little Ice Age (LIA) occurred widely across many glaciated regions in both hemispheres. To understand the climatic mechanisms driving this widespread phenomenon, it is essential to determine whether the LIA was a truly global event or if it was confined to specific regions.

Exploring cosmogenic-nuclide-dated moraine chronologies offers a powerful method to address this question. This approach leverages several key advantages:

• Measurements of cosmogenic nuclides in moraine boulders enable direct dating of moraine deposition, marking the end of a glacier's advance.
• Advances in cosmogenic nuclide dating techniques have made them sufficiently precise to identify individual glacier advances within the Late Holocene, including those associated with the LIA.
• An increasing number of Late Holocene moraine records, including those from the LIA, are now available from many regions around the world, allowing for a more comprehensive analysis.

In this contribution, we first present examples of well-resolved cosmogenic nuclide records of Late Holocene and LIA moraines. We then analyze a global dataset of cosmogenic-nuclide-dated moraine boulders to unravel the spatial patterns of LIA occurrence across different regions. Finally, we discuss potential climate forcings that could explain these patterns.