A 1,200-year perspective of 21st century drought in southwestern North America

Abstract

A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, ∼AD 900-1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1°C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.climate change | water resources | paleoclimatology | medieval period C limate-change projections clearly indicate what observations already suggest: Temperatures everywhere will be warmer in the future due to anthropogenic activities. General circulation models (GCMs) project continued warming, with annual temperatures 3-5°C above current levels by the end of the century (1). As previous articles in this Special Feature have discussed, warming temperatures, even without reductions in precipitation, will have far-reaching impacts on hydrologic sustainability in the Southwest. Twenty-first century droughts will occur under warmer temperatures with greater rates of evapotranspiration than occurred during the major droughts of the 20th century. Warming may also directly and indirectly increase the propensity for droughts in the Southwest (2-4). However, major 20th century droughts pale in comparison to droughts documented in paleoclimatic records over the past two millennia (5). Thus, warm droughts of the prehistoric past might provide evidence useful in understanding the current climatological changes, and for providing scenarios for worst-case droughts of the future and evidence of hydroclimatic responses in the Southwest to warmer climatic conditions. This paper examines recent temperature-drought relations and analyzes paleoclimatic data docum...

Variable North Pacific influence on drought in southwestern North America since AD 854

“…3) when EEP SSTs were warm 11 , suggesting that some droughts could be driven more by NPDV than ENSO. Interestingly, the warmest Kuroshio Extension SSTs occurred during the LIA, from ∼1,700 to 1,800, and the coolest occurred during the early twentieth century, a time in which SWNA was wetter than any other period of the past ∼1,000 years 1,26 . The reconstructed Palmer Drought Severity Index 1 (PDSI) from grid points near the study site (Fig.…”

Projections of declining surface-water availability for the southwestern United States

“…Furthermore, a 1,200-year tree-ring reconstruction of Colorado River flow at Lee's Ferry 27 has the very lowest value of 20-year means (during the twelfth-century megadrought), about 15% lower than the long-term mean (see also ref. 28). Hence, anthropogenic climate change is projected to lead to a potential reduction of Colorado River flow comparable to the most severe, but temporary, long-term decreases in flow recorded.…”

Efecto del cambio climático en el potencial productivo del frijol en México

“…El incremento de temperatura causado por el aumento en la concentración atmosférica de los gases efecto invernadero (GEI) (IPCC, 2013), propicia entre otras cosas la desecación de muchas regiones debido al aumento de la evaporación (Woodhouse et al, 2010) y de la modificación de los patrones de lluvia (Durán et al, 2014).…”

“…Temperature rise caused by the increase in atmospheric concentration of greenhouse gases (GHG) (IPCC, 2013), promotes among other things the drying in many regions due to increased evaporation (Woodhouse et al, 2010) and modification of rainfall patterns (Duran et al, 2014).…”