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https://doi.org/10.5194/egusphere-2025-1990
https://doi.org/10.5194/egusphere-2025-1990
15 May 2025
 | 15 May 2025
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

The Influence of Glacial Northern Hemisphere Ice Sheets On Atmospheric Circulation

Himadri Saini, David K. Hutchinson, Josephine R. Brown, Russell N. Drysdale, Yanxuan Du, and Laurie Menviel

Abstract. During the last glacial period, Northern Hemisphere (NH) ice sheets significantly influenced atmospheric circulation, yet their broader impacts beyond the North Atlantic remain underexplored. Using the Australian Earth System Model (ACCESS-ESM1.5), we simulate a glacial climate around 49,000 years ago (49 ka) during Marine Isotope Stage 3 (MIS 3, 65–25 ka), a period marked by prominent millennial-scale variability. Our findings demonstrate that the NH ice sheets induced a southward shift of the NH westerlies, increasing rainfall over Eurasia during boreal summer while reducing it in winter. The ice sheets' influence also extended across the tropics and the Southern Hemisphere (SH), driving a southward displacement of the Intertropical Convergence Zone (ITCZ) and the NH Hadley cell during austral summer, intensifying Australian rainfall. Additionally, including the Laurentide and Antarctic ice sheets (LIS and AIS) shifts the SH Hadley cell and the SH westerlies equatorward during JJA. These findings highlight the non-linear interactions between ice sheets, large-scale atmospheric circulation, and precipitation patterns.

Competing interests: At least one of the (co-)authors is a member of the editorial board of Climate of the Past.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Himadri Saini, David K. Hutchinson, Josephine R. Brown, Russell N. Drysdale, Yanxuan Du, and Laurie Menviel

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Himadri Saini, David K. Hutchinson, Josephine R. Brown, Russell N. Drysdale, Yanxuan Du, and Laurie Menviel
Himadri Saini, David K. Hutchinson, Josephine R. Brown, Russell N. Drysdale, Yanxuan Du, and Laurie Menviel

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Short summary
This study examines how large ice sheets during the last Ice Age influenced global weather patterns. We found that the presence of these ice sheets affected rainfall patterns in regions like Eurasia and Australia. By altering wind and weather systems, they shifted the position of the tropical rainbelt and impacted the circulation of air in both the Northern and Southern Hemispheres. Our research helps us understand past climate changes and their potential effects on future climate patterns.
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