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Glacier fluctuations in the northern Patagonian Andes (44°S) imply wind-modulated interhemispheric in-phase climate shifts during Termination 1.

ABSTRACT: The Last Glacial Termination (T1) featured major changes in global circulation systems that led to a shift from glacial to interglacial climate. While polar ice cores attest to an antiphased thermal pattern at millennial timescales, recent well-dated moraine records from both hemispheres suggest in-phase fluctuations in glaciers through T1, which is inconsistent with the bipolar see-saw paradigm. Here, we present a glacier chronology based on 30 new ¹⁰Be surface exposure ages from well-preserved moraines in the Lago Palena/General Vintter basin in northern Patagonia (~ 44°S). We find that the main glacier lobe underwent profound retreat after 19.7 ± 0.7 ka. This recessional trend led to the individualization of the Cerro Riñón glacier by ~ 16.3 ka, which underwent minor readvances at 15.9 ± 0.5 ka during Heinrich Stadial 1, during the Antarctic Cold Reversal with successive maxima at 13.5 ± 0.4, 13.1 ± 0.4, and 13.1 ± 0.5 ka, and a minor culmination at 12.5 ± 0.4 ka during Younger Dryas time. We conclude that fluctuations of Patagonian glaciers during T1 were controlled primarily by climate anomalies brought by shifts in the Southern Westerly Winds (SWW) locus. We posit that the global covariation of mountain glaciers during T1 was linked to variations in atmospheric CO₂ (atmCO₂) promoted by the interplay of the SWW-Southern Ocean system at millennial timescales.

SUBMITTER: Soteres RL

PROVIDER: S-EPMC9237032 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Glacier fluctuations in the northern Patagonian Andes (44°S) imply wind-modulated interhemispheric in-phase climate shifts during Termination 1.

Soteres Rodrigo L RL Sagredo Esteban A EA Kaplan Michael R MR Martini Mateo A MA Moreno Patricio I PI Reynhout Scott A SA Schwartz Roseanne R Schaefer Joerg M JM

Scientific reports 20220627 1

The Last Glacial Termination (T1) featured major changes in global circulation systems that led to a shift from glacial to interglacial climate. While polar ice cores attest to an antiphased thermal pattern at millennial timescales, recent well-dated moraine records from both hemispheres suggest in-phase fluctuations in glaciers through T1, which is inconsistent with the bipolar see-saw paradigm. Here, we present a glacier chronology based on 30 new <sup>10</sup>Be surface exposure ages from wel ...[more]

PMID: 35761034

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Project description:Electrophysiological studies have long demonstrated a high degree of correlated activity between the left and right hemispheres, however little is known about regional variation in this interhemispheric coordination. Whereas cognitive models and neuroanatomical evidence suggest differences in coordination across primary sensory-motor cortices versus higher-order association areas, these have not been characterized. Here, we used resting-state functional magnetic resonance imaging data acquired from 62 healthy volunteers to examine interregional correlation in spontaneous low-frequency hemodynamic fluctuations. Using a probabilistic atlas, we correlated probability-weighted time series from 112 regions comprising the entire cerebrum. We then examined regional variation in correlated activity between homotopic regions, contrasting primary sensory-motor cortices, unimodal association areas, and heteromodal association areas. Consistent with previous studies, robustly correlated spontaneous activity was noted between all homotopic regions, which was significantly higher than that between nonhomotopic (heterotopic and intrahemispheric) regions. We further demonstrated substantial regional variation in homotopic interhemispheric correlations that was highly consistent across subjects. Specifically, there was a gradient of interhemispheric correlation, with highest correlations across primary sensory-motor cortices (0.758, SD=0.152), significantly lower correlations across unimodal association areas (0.597, SD=0.230) and still lower correlations across heteromodal association areas (0.517, SD=0.226). These results demonstrate functional differences in interhemispheric coordination related to the brain's hierarchical subdivisions. Synchrony across primary cortices may reflect networks engaged in bilateral sensory integration and motor coordination, whereas lower coordination across heteromodal association areas is consistent with functional lateralization of these regions. This novel method of examining interhemispheric coordination may yield insights regarding diverse disease processes as well as healthy development.

Dataset Information

Glacier fluctuations in the northern Patagonian Andes (44°S) imply wind-modulated interhemispheric in-phase climate shifts during Termination 1.

Publications

Glacier fluctuations in the northern Patagonian Andes (44°S) imply wind-modulated interhemispheric in-phase climate shifts during Termination 1.

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