The dynamics of warming during the last deglaciation in high-elevation regions of Eastern Equatorial Africa

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dc.citation.articleNumber107416
dc.citation.journalTitleQuaternary Science Reviews
dc.citation.volumeNumber281
dc.contributor.authorGarelick, Sloane
dc.contributor.authorRussell, James
dc.contributor.authorRichards, Adin
dc.contributor.authorSmith, Jamila
dc.contributor.authorKelly, Meredith
dc.contributor.authorAnderson, Nathan
dc.contributor.authorJackson, Margaret S.
dc.contributor.authorDoughty, Alice
dc.contributor.authorNakileza, Bob
dc.contributor.authorIvory, Sarah
dc.contributor.authorDee, Sylvia
dc.contributor.authorMarshall, Charlie
dc.date.accessioned2022-04-18T17:17:28Z
dc.date.available2022-04-18T17:17:28Z
dc.date.issued2022
dc.description.abstractTropical mountain environments, such as the Rwenzori Mountains in equatorial Africa, are thought to be particularly sensitive to climate change. Ongoing warming in the Rwenzori is impacting local environments and communities through glacial retreat, fires, and flooding. Paleoclimate reconstructions from elsewhere in Africa suggest considerable warming accompanied glacier retreat during the last glacial termination, from ∼21 thousand years before present (ka) through the early to mid-Holocene. Quantifying these changes has been difficult but could help to assess future impacts in the Rwenzori. Here, we present a ∼21 thousand-year (kyr) temperature reconstruction based on the relative abundance of branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Lake Mahoma (2,990 m above sea level; m asl) in the Rwenzori Mountains, Uganda. Our record, paired with existing Rwenzori glacial moraine 10Be exposure ages, suggests that deglacial warming and glacial retreat began by ∼20 ka and accelerated at ∼18–18.5 ka. The timing of the onset of rapid warming matches the timing of the post-glacial rise in radiative forcing from atmospheric greenhouse gases (GHGs) from Antarctic ice cores (Brook et al., 1996; Marcott et al., 2014; Monnin et al., 2004; Schilt et al., 2010). Our temperature reconstruction registers ∼4.9 °C warming from the Last Glacial Maximum (LGM) to the late Holocene. This increase is larger than the average ∼2-4 °C warming observed in records from lower elevation sites in tropical East Africa, but similar to that observed at other high-elevation sites in this region. The increased warming at higher elevations thus confirms that the temperature lapse rate steepened during the LGM over this region. Our results also indicate ∼3 °C of warming during the mid-Holocene relative to the late Holocene. This suggests that the freezing-level height rose above Rwenzori summit elevations at that time, likely causing complete deglaciation of the Rwenzori Mountains from ∼5 to 7 ka. The mid-Holocene is thus a potential analog for the glacial and environmental changes that these mountains are likely to experience in the coming decades. Overall, the timing and magnitude of temperature change observed in our record has important implications for climate model projections of future warming in tropical Africa.
dc.identifier.citationGarelick, Sloane, Russell, James, Richards, Adin, et al.. "The dynamics of warming during the last deglaciation in high-elevation regions of Eastern Equatorial Africa." <i>Quaternary Science Reviews,</i> 281, (2022) Elsevier: https://doi.org/10.1016/j.quascirev.2022.107416.
dc.identifier.doihttps://doi.org/10.1016/j.quascirev.2022.107416
dc.identifier.urihttps://hdl.handle.net/1911/112102
dc.language.isoeng
dc.publisherElsevier
dc.titleThe dynamics of warming during the last deglaciation in high-elevation regions of Eastern Equatorial Africa
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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