{"NOAAStudyId":"9958","contactInfo":{"address":"325 Broadway, E/NE31","city":"Boulder","constraints":"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.","country":"USA","dataCenterUrl":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data","email":"paleo@noaa.gov","fax":"303-497-6513","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","phone":"303-497-6280","postalCode":"80305-3328","shortName":"DOC/NOAA/NESDIS/NCEI","state":"CO","type":"CONTACT INFORMATION"},"contributionDate":"2010-07-19","dataPublisher":"NOAA","dataType":"OTHER COLLECTIONS","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/other-collections","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-other-9958.xml","doi":null,"earliestYearBP":4877,"earliestYearCE":-2927,"entryId":"noaa-other-9958","funding":[{"fundingAgency":"Leverhulme Trust","fundingGrant":null}],"investigators":"Chase, B.M.; Meadows, M.E.; Carr, A.S.; Reimer, P.J.","mostRecentYearBP":1461,"mostRecentYearCE":489,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/9958","originalSource":null,"publication":[{"abstract":"Presented here are stable nitrogen isotope data from a rock hyrax \n(Procavia capensis) middens from northwestern Namibia that record \na series of rapid aridification events beginning at ca. 3800 cal \nyr BP, and which mark a progressive decrease in regional humidity \nacross the Holocene. Strong correlations exist between this record \nand other terrestrial and marine archives from southern Africa, \nindicating that the observed pattern of climate change is regionally \ncoherent. Combined, these data indicate hemispheric synchrony in \ntropical African climate change during the Holocene, with similar \ntrends characterising the termination of the 'African Humid Period' \n(AHP) in both the northern and southern tropics. These findings \nrun counter to the widely accepted model of direct low-latitude \ninsolation forcing, which requires an antiphase relationship to \nexist between the hemispheres. The combined dataset highlights: \n1) the importance of forcing mechanisms influencing the high \nnorthern latitudes in effecting low-latitude climate change in \nAfrica, and 2) the potential importance of solar forcing and \nvariations in the Earth's geomagnetic shield in determining \nboth long-term and rapid centennial-scale climate changes, \nidentifying a possible mechanism for the variations marking \nthe AHP termination in both the southern and northern tropics. \n","author":null,"citation":"Chase, B.M., M.E. Meadows, A.S. Carr, and P.J. Reimer. 2010. \nEvidence for progressive Holocene aridification in southern Africa \nrecorded in Namibian hyrax middens: Implications for African Monsoon \ndynamics and the \"African Humid Period\". \nQuaternary Research, Vol. 74, pp. 36-45. \ndoi:10.1016/j.yqres.2010.04.006 \n","edition":null,"identifier":{"id":"10.1016/j.yqres.2010.04.006","type":"doi","url":"http://dx.doi.org/10.1016/j.yqres.2010.04.006"},"issue":null,"journal":"Quaternary Research","pages":null,"pubRank":"1","pubYear":2010,"reportNumber":null,"title":"Evidence for progressive Holocene aridification in southern Africa  recorded in Namibian hyrax middens: Implications for African Monsoon  dynamics and the \"African Humid Period\"","type":"publication","volume":null}],"reconstruction":"N","scienceKeywords":null,"site":[{"NOAASiteId":"31570","geo":{"geoType":"Feature","geometry":{"coordinates":["-20.4638","14.4423"],"type":"POINT"},"properties":{"easternmostLongitude":"14.4423","maxElevationMeters":null,"minElevationMeters":null,"northernmostLatitude":"-20.4638","southernmostLatitude":"-20.4638","westernmostLongitude":"14.4423"}},"locationName":"Continent>Africa>Southern Africa>Namibia","mappable":"Y","paleoData":[{"NOAADataTableId":"20352","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>others"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/midden/africa/austerlitz2010d15n.txt","linkText":"austerlitz2010d15n.txt","urlDescription":"Data","variables":[]},{"NOAAKeywords":["earth science>paleoclimate>others"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/midden/africa/austerlitz2010d15n.xls","linkText":"austerlitz2010d15n.xls","urlDescription":"Data","variables":[]}],"dataTableName":"HyraxMidden","dataTableNotes":null,"earliestYear":4877,"earliestYearBP":4877,"earliestYearCE":-2927,"mostRecentYear":1461,"mostRecentYearBP":1461,"mostRecentYearCE":489,"species":[],"timeUnit":"cal yr BP"}],"siteName":"Austerlitz Cave"}],"studyCode":null,"studyName":"Namibia 5000 Year Rock Hyrax Midden Nitrogen Isotope Data","studyNotes":"This dataset comprises stable nitrogen isotope data from \na rock hyrax (Procavia capensis) middens from northwestern \nNamibia that record a series of rapid aridification events \nbeginning at c. 3800 cal yr BP, and which mark a progressive \ndecrease in regional humidity across the Holocene. Strong \ncorrelations exist between this record and other terrestrial \nand marine archives from southern Africa, indicating that \nthe observed pattern of climate change is regionally coherent. \nCombined, these data indicate hemispheric synchrony in tropical \nAfrican climate change during the Holocene, with similar trends \ncharacterising the termination of the 'African Humid Period' \n(AHP) in both the northern and southern tropics. These findings \nrun counter to the widely accepted model of direct low latitude \ninsolation forcing, which requires an anti-phase relationship \nto exist between the hemispheres. \nThe combined dataset highlights: \n1) the importance of forcing mechanisms influencing the high \nnorthern latitudes in effecting low latitude climate change \nin Africa, and 2) the potential importance of solar forcing \nand variations in the Earth's geomagnetic shield in determining \nboth long-term and rapid centennial-scale climate changes, \nidentifying a possible mechanism for the variations marking \nthe AHP termination in both the southern and northern tropics. \n\nStable isotope data (d15N) from a rock hyrax midden recovered \nfrom northwest-facing Austerlitz cave in northwestern Namibia \n(20°27.83'S, 14°26.54'E) on the southern margin of the \nlimestone karstveld region, south of the Etendeka \nand Kamajab plateaus. \n\nAMS radiocarbon analyses of the Austerlitz midden indicate \nthat it was deposited between 4538-4825 cal (calibrated) yr BP \n(UBA 9441) and 1385-1522 cal yr BP (UBA-9436). The distribution \nof ages as a function of depth shows continuous deposition, \nwith no apparent hiatuses. Accumulation rates average ~30 µm yr-1, \nwith slightly higher rates (~48 µm yr-1) at the base of the section. \nEach 1 mm isotope sample thus integrates approximately 20 – 35 \nyears of accumulation. \n\nThe d15N values of the Austerlitz midden vary from 12.5 to -19.4‰. \nFrom the beginning of the record, there is a clear, progressive \nenrichment in d15N values, with sharp increases occurring between \nc. 3500 – 3400 cal yr BP and c. 3000 – 2800 cal yr BP. These trends \nshow close similarities with the d15N record from the hyrax middens \nrecovered from Spitzkoppe massif, 160 km to the southwest \n(Chase et al., 2009), and reveal a coherent, regional-scale midden \n15N signal at this time. \n\nThe potential of nitrogen stable isotope compositions as a climatic \nindicator has long been recognised, but studies of modern ecosystems \nhave produced complex data sets, that have proved difficult to \ninterpret (e.g. Heaton, 1987; Heaton et al., 1986). Among herbivores, \n15N abundance in animal tissues is strongly influenced by climate, \ndiet and/or physiology (Ambrose and DeNiro, 1986; Heaton et al., 1986). \nWhile early studies focused on the possible effects that animal \nmetabolism would have on the signal (Ambrose and DeNiro, 1986), \nsubsequent studies of d15N values in plants across aridity gradients \nhave indicated that it may not be necessary to look towards herbivore \nmetabolism for the link between d15N values and rainfall, as clear \ncorrelations are identified between higher d15N values and decreased \nrainfall in both C3 and C4 plants (Heaton, 1987; Murphy and Bowman, \n2006; Swap et al., 2004) and soils (Aranibar et al., 2004). \nMurphy and Bowman's (2006) spatially-extensive studies of d15N \nvalues in both grass and kangaroo bone from across Australia reveal \na remarkably consistent relationship between plant and bone d15N \nsignals, suggesting that water availability, through its influence \non the isotopic signature of plants/diet, is the primary control \non animal d15N with metabolism having no clear effect. \n\n","version":"1.0","xmlId":"8851"}