A 1,500-year record of late Holocene temperature variability and recent warming from Laguna Chingaza, Colombia

dc.contributor.advisorShanahan, Timothy M.
dc.creatorBixler, Curtis Williamen
dc.date.accessioned2013-11-14T21:28:32Zen
dc.date.issued2012-08en
dc.date.submittedAugust 2012en
dc.date.updated2013-11-14T21:28:34Zen
dc.descriptiontexten
dc.description.abstractRapid tropical glacier retreat over the last 50 years has been well documented, and has received significant media attention. Many studies suggest these changes are due to rising global surface air temperatures, however disentangling the effects of temperature and precipitation has hampered scientific consensus. Furthermore, because of the shortness of the instrumental record, it is difficult to assess the larger significance of the climate changes associated with the decline of tropical glaciers. Here, we present a locally calibrated, independent temperature reconstruction for the past 1,500 years from Laguna Chingaza, Colombia based on distributions of branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) in order to assess the controls on long term temperature variability in the tropical Andes, and their relationship with growth and demise of Andean glaciers. Comparison of reconstructed temperatures with the instrumental record suggests that our proxy record faithfully records decadal to century scale trends in temperature. The largest temperature decline over the last 1,500 years was a decrease of 2.5 ± 0.3 °C during the Little Ice Age (LIA), reaching lowest temperatures during the mid-17th century, and is broadly consistent with terrestrial temperature reconstructions throughout the tropics and the higher latitudes. The structure and timing of temperature changes at Laguna Chingaza are remarkably similar to recent terrestrial temperature reconstructions from elsewhere in the tropics, including sites in the tropical Pacific and equatorial Africa, suggesting that these changes are widespread in the tropics. Together, these records suggest that warming over the last few decades is unprecedented over the last 1,500 years, including the Medieval Climate Anomaly (800-1150 AD). Comparison of these temperature changes with records of Andean glacier limits suggests that temperature is the dominant driver of glacial retreat, particularly over the past few decades. Additionally, paleotemperatures inferred from LIA and recent glacial equilibrium line altitudes (ELAs) underestimate past changes in temperature when compared with brGDGTs reconstructions, suggesting that changes in precipitation complicate the use of glacier ELAs to reconstruct past temperatures. The coupling of temperature and ice extent in South America suggests that with projected future warming, the health of tropical glaciers could be in jeopardy, significantly impacting the communities and ecosystems that depend on them.en
dc.description.departmentEarth and Planetary Sciencesen
dc.embargo.lift8/1/2013en
dc.embargo.terms8/1/2013en
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/22192en
dc.language.isoen_USen
dc.subjectPaleoclimateen
dc.subjectBiomarkersen
dc.subjectGDGTen
dc.subjectPaleotemperatureen
dc.subjectPaleolimnologyen
dc.subjectHoloceneen
dc.subjectLaguna Chingazaen
dc.subjectColombiaen
dc.subjectGlacieren
dc.subjectTropical glacieren
dc.titleA 1,500-year record of late Holocene temperature variability and recent warming from Laguna Chingaza, Colombiaen
thesis.degree.departmentGeological Sciencesen
thesis.degree.disciplineGeological Sciencesen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Science in Geological Sciencesen

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