noaa-lake-13676 Sacred Lake, Mt. Kenya 47000 Year GDGT Temperature Reconstruction Loomis, S.E.; Russell, J.M.; Ladd, B.; Street-Perrott, F.A.; Sinninghe Damsté, J.S. Sacred Lake, Mt. Kenya 47000 Year GDGT Temperature Reconstruction 2013-01-16 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/13676 Investigator S.E. Loomis Investigator J.M. Russell Investigator B. Ladd Investigator F.A. Street-Perrott Investigator J.S. Sinninghe Damsté earth science paleoclimate climate reconstructions|paleolimnology depth,null,null,centimeter,null,climate reconstructions|paleolimnology,corrected,null,N,null earth science paleoclimate climate reconstructions|paleolimnology age,null,null,calendar year before present,null,climate reconstructions|paleolimnology,null,null,N,null earth science paleoclimate climate reconstructions|paleolimnology surface air temperature,glycerol dialkyl glycerol tetraether index,one standard deviation,degree Celsius,annual,climate reconstructions|paleolimnology,null,null,N,brGDGT earth science paleoclimate climate reconstructions|paleolimnology surface air temperature,glycerol dialkyl glycerol tetraether index,null,degree Celsius,annual,climate reconstructions|paleolimnology,null,null,N,brGDGT earth science paleoclimate paleolimnology reconstruction geoscientificInformation Air Temperature Reconstruction 47730 cal yr BP 63 cal yr BP Complete .0833 .0833 37.5333 37.5333 2350 2350 Continent Africa Eastern Africa Kenya Sacred Lake GDGT>LATITUDE .0833>LONGITUDE 37.5333 None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Shannon E. Loomis, James M. Russell, Bethany Ladd, F. Alayne Street-Perrott, Jaap S. Sinninghe Damsté. 2012. Calibration and application of the branched GDGT temperature proxy on East African lake sediments. Earth and Planetary Science Letters, Vol. 357-358, pp. 277-288. DOI: 10.1016/j.epsl.2012.09.031

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a novel proxy for mean annual air temperature (MAAT) and have the potential to be broadly applicable to climate reconstruction using lacustrine sediments. Several calibrations have been put forth relating brGDGT distributions to MAAT using a variety of linear regressions, including the methylation (MBT) and cyclization (CBT) indices of brGDGTs, the relative abundances of the major, non-cyclized brGDGTs (MbrGDGTs), and best subsets regression (BSR) of the fractional abundances of the nine most common brGDGTs. However, these calibrations have rarely been applied to lake sediment cores to reconstruct temperatures and test the applicability of this proxy as a paleothermometer. We present an expanded East African lakes surface sediment brGDGT dataset based upon 111 lakes and examine three methods of calibrating brGDGTs to MAAT. These methods include recalculations of the East African lake MBT/CBT calibration and MbrGDGTs calibrations, as well as a new stepwise forward selection (SFS) calibration that uses the four combined brGDGTs that explain the most variance in temperature in our calibration set. We apply these new calibrations as well as five previously published lacustrine brGDGT calibrations to the brGDGT distributions of our surface sediment dataset and a 48 kyr sediment core from Sacred Lake, Mt. Kenya, producing the first brGDGT temperature reconstruction available from a small tropical lake. We compare the reconstructed temperatures to previously published paleotemperature records from East Africa to help us assess the performance of the brGDGT calibrations. We find that the SFS calibration has a consistently low root mean squared error of prediction (RMSEP) over the entire range of MAAT, while the MBT/CBT and MbrGDGT calibrations have relatively large RMSEPs, particularly between lakes with similar temperatures but variable pH. This suggests that these techniques do not properly deconvolve the temperature and pH signals recorded in the distributions of the brGDGTs. We further find that only the SFS calibration produces a credible reconstructed temperature history from Sacred Lake when compared to other last glacial maximum paleotemperature estimates from East Africa. Thus, we advocate for the use of the SFS calibration when reconstructing paleotemperatures from brGDGTs in East Africa. STUDY NOTES: This dataset contains depth, age, reconstructed temperatures, and bootstrap errors on the temperature reconstruction from a core from Sacred Lake, Mt. Kenya. Temperatures were reconstructed from branched GDGTs using the Loomis et al. (2012) stepwise forward selection (SFS) calibration.

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/eastafrica/sacred2012.txt USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11