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1. Similar Holocene glaciation histories in tropical South America and Africa

   https://doi.org/10.1130/G48059.1  

   Vickers, Anthony C.; Shakun, Jeremy D.; Goehring, Brent M.; Gorin, Andrew; Kelly, Meredith A.; Jackson, Margaret S.; Doughty, Alice; Russell, James (September 2020, Geology)

   null (Ed.)

   Abstract Tropical glaciers have retreated alongside warming temperatures over the past century, yet the way in which these trends fit into a long-term geological context is largely unclear. Here, we present reconstructions of Holocene glacier extents relative to today from the Quelccaya ice cap (Peru) and the Rwenzori Mountains (Uganda) based on measurements of in situ14C and 10Be from recently exposed bedrock. Ice-extent histories are similar at both sites and suggest that ice was generally smaller than today during the first half of the Holocene and larger than today for most, if not all, of the past several millennia. The similar glaciation history in South America and Africa suggests that large-scale warming followed by cooling of the tropics during the late Holocene primarily drove ice extent, rather than regional changes in precipitation. Our results also imply that recent tropical ice retreat is anomalous in a multimillennial context. 

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2. Four North American glaciers advanced past their modern positions thousands of years apart in the Holocene

   https://doi.org/10.5194/tc-17-5459-2023  

   Jones, Andrew G; Marcott, Shaun A; Gorin, Andrew L; Kennedy, Tori M; Shakun, Jeremy D; Goehring, Brent M; Menounos, Brian; Clark, Douglas H; Romero, Matias; Caffee, Marc W (January 2023, The Cryosphere)

   Abstract. There is unambiguous evidence that glaciers have retreated from their 19th century positions, but it is less clear how far glaciers have retreated relative to their long-term Holocene fluctuations. Glaciers in western North America are thought to have advanced from minimum positions in the Early Holocene to maximum positions in the Late Holocene. We assess when four North American glaciers, located between 38–60∘ N, were larger or smaller than their modern (2018–2020 CE) positions during the Holocene. We measured 26 paired cosmogenic in situ 14C and 10Be concentrations in recently exposed proglacial bedrock and applied a Monte Carlo forward model to reconstruct plausible bedrock exposure–burial histories. We find that these glaciers advanced past their modern positions thousands of years apart in the Holocene: a glacier in the Juneau Icefield (BC, Canada) at ∼2 ka, Kokanee Glacier (BC, Canada) at ∼6 ka, and Mammoth Glacier (WY, USA) at ∼1 ka; the fourth glacier, Conness Glacier (CA, USA), was likely larger than its modern position for the duration of the Holocene until present. The disparate Holocene exposure–burial histories are at odds with expectations of similar glacier histories given the presumed shared climate forcings of decreasing Northern Hemisphere summer insolation through the Holocene followed by global greenhouse gas forcing in the industrial era. We hypothesize that the range in histories is the result of unequal amounts of modern retreat relative to each glacier's Holocene maximum position, rather than asynchronous Holocene advance histories. We explore the influence of glacier hypsometry and response time on glacier retreat in the industrial era as a potential cause of the non-uniform burial durations. We also report mean abrasion rates at three of the four glaciers: Juneau Icefield Glacier (0.3±0.3 mm yr−1), Kokanee Glacier (0.04±0.03 mm yr−1), and Mammoth Glacier (0.2±0.2 mm yr−1). 

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3. Paleoclimatic implications of glacial fluctuations in the Sierra Nevada del Cocuy, northern Andes, Colombia, during the Lateglacial and Holocene

   https://doi.org/10.1016/j.quascirev.2025.109458  

   Herbert, Jordan N; Bromley, Gordon RM; Kelly, Meredith A; Doughty, Alice M; Ruiz-Carrascal, Daniel; Restrepo-Moreno, Sergio A; Londoño, Santiago Noriega; Galloway, Peter; Hidy, Alan J (September 2025, Quaternary Science Reviews)

   The reconstruction of former mountain glaciers from geomorphic mapping and cosmogenic-nuclide surface exposure dating provides a unique opportunity to infer patterns of past terrestrial climate variability. Tropical mountain glaciers are particularly valuable as there are comparatively few terrestrial climate proxies at equatorial latitudes relative to higher latitudes. As the single largest climate zone on Earth, the tropics play an outsized role in mediating global climate via the ocean-atmosphere transfer of latent heat and water vapor. Nonetheless, there remains a persistent gap in our understanding of how the tropics influenced – or were influenced by – the high-magnitude climate shifts of the Late Pleistocene, and whether this high-energy region simply responded to extratropical forcing or was itself a driver of global climatic change. To help address this knowledge gap, we analyzed geologic evidence for past glacial fluctuations in three adjacent valleys in the Sierra Nevada del Cocuy, the highest subrange of the Eastern Cordillera in the Colombian Andes, to provide a terrestrial record of atmospheric temperature during the latter part of Termination 1. Coupled with geomorphic mapping and paleo-snowline reconstructions, our beryllium-10 glacial chronology indicates that glaciers in the humid inner tropics underwent pronounced growth and gradual decay during the Antarctic Cold Reversal (14.5–12.8 ka) and Younger Dryas (12.8–11.7 ka) periods, respectively, following a trend that, according to directly dated moraine records from throughout both polar hemispheres, appears to have been global. While the specific mechanism(s) behind this large-scale behavior remains to be corroborated, we revisit the hypothesis that ocean atmosphere heat transfer and water vapor flux are key drivers of abrupt Lateglacial temperature fluctuations. Subsequent to the Lateglacial, deglaciation of the Sierra Nevada del Cocuy accelerated during the Early Holocene, a pattern also observed in other tropical glacier records. More recently, the magnitude of snowline rise and glacier retreat over the last two centuries supports the view that modern tropospheric warming is anomalously strong at least relative to the last ~16,000 years. 

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4. Rock Glacier Movement and Debris Transport Over Annual to Multi‐Millennial Timescales

   https://doi.org/10.1029/2023JF007453  

   Munroe, Jeffrey S.; Laabs, Benjamin J. C.; Corbett, Lee B.; Bierman, Paul R.; Handwerger, Alexander L. (April 2024, Journal of Geophysical Research: Earth Surface)

   Abstract Rock glaciers are common in alpine landscapes, but their evolution over time and their significance as agents of debris transport are not well‐understood. Here, we assess the movement of an ice‐cemented rock glacier over a range of timescales using GPS surveying, satellite‐based radar, and cosmogenic¹⁰Be surface‐exposure dating. GPS and InSAR measurements indicate that the rock glacier moved at an average rate of ∼10 cm yr⁻¹in recent years. Sampled boulders on the rock glacier have cosmogenic surface‐exposure ages from 1.2 to 10 ka, indicating that they have been exposed since the beginning of the Holocene. Exposure ages increase linearly with distance downslope, suggesting a slower long‐term mean surface velocity of 3 ± 0.3 cm yr⁻¹. Our findings suggest that the behavior of this rock glacier may be dominated by episodes of dormancy punctuated by intervals of relatively rapid movement over both short and long timescales. Our findings also show that the volume of the rock glacier corresponds to ∼10 m of material stripped from the headwall during the Holocene. These are the first cosmogenic surface‐exposure ages to constrain movement of a North American rock glacier, and together with the GPS and satellite radar measurements, they reveal that rock glaciers are effective geomorphic agents with dynamic multi‐millennial histories. 

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5. Recent research in the Bladen nature reserve: the preceramic occupations of Mayahak Cab Pek and Saki Tzul rockshelters

   Prufer, Keith M. (January 2020, Research reports in Belizean archaeology)

   null (Ed.)

   From the perspective of Central America, the peopling of the New World was a complex process lasting thousands of years and involving multiple waves of migration in the late Pleistocene and early Holocene periods. As the ice age ended across the New World people were adapting to changing environments and resources. In the Neotropics these changes would have been pronounced as patchy forests and grasslands gave way to broadleaf tropical forests. Investigations since 2014 are demonstrating that early Holocene humans lived, hunted, and were buried in and around rockshelters in the Bladen Nature Reserve. Data from these studies are illuminating the life histories and subsistence strategies of these earliest colonists of the lowland tropics 

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