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</o:shapelayout></xml><![endif]--></head><body lang=ES link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:8.5pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'>PNAS April 14, 2020 vol. 117 no. 15 8271–8279 <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'>First published April 13, 2020.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'><a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1912242117"><span style='color:windowtext;text-decoration:none'>www.pnas.org/cgi/doi/10.1073/pnas.1912242117</span></a><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-size:20.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru</span></b><span lang=EN-US style='font-size:20.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'>Daniel H. Sandweissa,b,1, C. Fred T. Andrus c, Alice R. Kelley b,d, Kirk A. Maasch b,d, Elizabeth J. Reitze, and Paul B. Roscoe a,b<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-family:"Arial","sans-serif";mso-fareast-language:ES'>aDepartment of Anthropology, University of Maine, Orono, ME 04469; bClimate Change Institute, University of Maine, Orono, ME 04469; cDepartment of Geological Sciences, University of Alabama, Tuscaloosa, AL 35487; dSchool of Earth and Climate Sciences, University of Maine, Orono, ME 04469; and e Georgia Museum of Natural History, University of Georgia, Athens, GA 306021.To whom correspondence may be addressed. Email: <a href="mailto:dan.sandweiss@maine.edu">dan.sandweiss@maine.edu</a></span><span lang=EN-US style='font-size:10.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>.</span><span lang=EN-US style='font-size:8.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'> </span><span lang=EN-US style='font-size:8.5pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:8.5pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>Archaeological evidence plays a key role in longitudinal studies of humans and climate. Climate proxy data from Peruvian archaeological sites provide a case study through insight into the history of the “flavors” or varieties of El Niño (EN) events after</span><span lang=EN-US style='font-size:12.0pt;font-family:"Cambria Math","serif";mso-fareast-language:ES'>∼</span><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>11 ka: eastern Pacific EN, La Niña, coastal EN (COA), and central Pacific or Modoki EN (CP). <u>Archaeological proxies are important to the coastal Peruvian case because more commonly used paleoclimate proxies are unavailable or equivocal</u>. Previously, multiproxy evidence from the Peruvian coast and elsewhere suggested that EN frequency varied over the Holocene: 1) present in the Early Holocene; 2) absent or very low frequency during the Middle Holocene (</span><span lang=EN-US style='font-size:12.0pt;font-family:"Cambria Math","serif";mso-fareast-language:ES'>∼</span><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>9 to 6 ka); 3) low after</span><span lang=EN-US style='font-size:12.0pt;font-family:"Cambria Math","serif";mso-fareast-language:ES'>∼</span><span lang=EN-US style='font-size:12.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>6 ka; and 4) rapidly increasing frequency after 3 ka. Despite skepticism about the reliability of archaeological proxies, non-archaeological proxies seemed to confirm this archaeological EN reconstruction. Although there is consensus that EN frequency varied over this period, some non-archaeological and archaeological proxies call parts of this reconstruction into question. Here we review Holocene EN frequency reconstructions for the Peruvian coast, point to complexities introduced by apparent contradictions in a range of proxy records, consider the impact of CP and COA phenomena, and assess the merits of archaeological proxies in EN reconstructions. Reconciling Peruvian coastal paleoclimate data is critical for testing models of future EN behavior under climate variability. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:8.0pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'>.</span><span lang=EN-US style='font-size:8.5pt;font-family:"Arial","sans-serif";mso-fareast-language:ES'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br /> <table style="border-top: 1px solid #D3D4DE;">
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