Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru

Abstract

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 ∼11 ka: eastern Pacific EN, La Niña, coastal EN (COA), and central Pacific or Modoki EN (CP). Archaeological proxies are important to the coastal Peruvian case because more commonly used paleoclimate proxies are unavailable or equivocal. 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 (∼9 to 6 ka); 3) low after ∼6 ka; and 4) rapidly increasing frequency after 3 ka. Despite skepticism about the reliability of archaeological proxies, nonarchaeological proxies seemed to confirm this archaeological EN reconstruction. Although there is consensus that EN frequency varied over this period, some nonarchaeological 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.

Reconnecting with the past and anticipating the future: A review of fisheries‐derived cultural ecosystem services in pre‐Hispanic Peru

“…Early dwellers complemented fishing with shellfish gathering along beaches. The latter being a very accessible activity with minimum required energy input that provided a reliable and nutritious staple (Quilter, 1992; Yesner, 1980).…”

Archaeology, climate, and global change in the Age of Humans

“…Collectively, these and other studies demonstrate that archaeological sites represent a series of observation networks about changing environmental conditions and human activities through time (Distributed Long-term Observing Networks of the Past), with much potential to address modern environmental challenges (24). This PNAS special feature brings together six globally distributed papers that demonstrate the value of archaeology within transdisciplinary research programs focused on integrating perspectives on past, present, and future climate change and related environmental challenges (25)(26)(27)(28)(29)(30). These papers demonstrate cutting-edge interdisciplinary research on archaeology, climate change, and other global environmental challenges, emphasizing how archaeology provides information of value to science and society in an era of global change, while, at the same time, sounding warning bells about the ongoing destruction of this critical record ( Fig.…”

“…Many of the papers in this special feature focus on human ecodynamics during the Holocene (25)(26)(27) and/or reconstruct past climate regimes from archaeological data (27). These studies recognize that climatic and environmental change do not explain all aspects of change in human organization, behavior, demography, or distribution, but each one provides examples in which people responded to changing conditions.…”

“…Humans have both actively shaped and inadvertently recorded past environments. Sandweiss et al (27) emphasize the underutilized contributions of archaeological climate proxies to paleoclimate reconstruction (their SI Appendix, table S1 lists both natural and archaeological climate proxies). In their case study of Holocene El Niño frequency variation, Sandweiss et al review problems with natural proxies for the Peruvian coast (the heartland of El Niño) and the historical precedence and value of archaeological proxies in recognizing and delineating this variation.…”

“…Using the Past to Look to the Future Increasingly, archaeologists look to the future, drawing on the unparalleled long-term record of human−environmental interactions to provide context and guidance for future environmental conditions, scenarios, and planning. The papers in this special feature illustrate some of the best examples of this research, providing regional and global examples of past human response to or influence on environmental change from the Arabian deserts to Africa, the Caribbean, Peru, Australia, and the United States of America (25)(26)(27). They also demonstrate the value of using existing archaeological collections and building new collections for future research of societal significance, an endeavor that is highly ethical but difficult to fund (29).…”