Understanding Nevada’s Current Drought in Historical and Paleoclimatic Context

Abstract

Nevada lies in one of the driest parts of North America. The region has long grappled with droughts and also with extended periods in which the already dry climate aridified for decades or centuries. Here we place Nevada’s most recent statewide drought (2020 – present) in the context of historical, archaeological and paleoclimate records dating back through the Mid-Holocene. The current drought is distinct from historical droughts that impacted the state in the 1930s, 1950s, and 1970’s and 1980s. It is notably warmer than droughts of the 20th century and more spatially extensive than any of these, although the 1930s drought also impacted much of the West. The early 2020s drought is also embedded within a two-decade long dry period, raising important questions about whether it is (1) drought, a relatively short period of abnormal dryness; (2) megadrought, a longer and typically more severe period of unusually dry conditions; (3) the manifestation of aridification, a shift toward a generally drier climate because of long-term precipitation declines and/or warming; or (4) some combination of the three. A broader view suggests that at least some aspects of drought since 2020 may not be unique. Paleoclimate evidence from cave deposits, lake and meadow sediments, animal middens, dead wood and tree rings indicate that Nevada and much of the western United States experienced decadal and centennial long dry periods in the Middle Holocene (5000 – 7000 years ago), the Late Holocene, (1800 – 3100 years ago), during the Medieval Climate Anomaly (1000 – 650 years ago) and again 600 – 500 years ago. The archaeological record shows that Indigenous Nevadans responded by repeatedly adapting to changing paleoenvironmental conditions. However, some key questions about fine-scale temporal and spatial variability in the experience of drought remain. Limitations in the spatial, seasonal and temporal resolutions of climate reconstructions—and in the observational record—may obscure the evidence for short or seasonally specific wet periods within longer dry periods or spatial variability in precipitation. Nonetheless, proxy and archaeological evidence from the last 10,000 years shows that understanding and responding to drought requires viewing drought on these time spans with an appreciation for the details that appear in modern observations.