Megadroughts in North America: placing IPCC projections of hydroclimatic change in a long‐term palaeoclimate context

Cook, Edward R.; Seager, Richard; Heim, Richard R.; Vose, Russell S.; Herweijer, Celine; Woodhouse, Connie A.

doi:10.1002/jqs.1303

Cited by 428 publications

(610 citation statements)

References 77 publications

(111 reference statements)

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“…We used threefold consecutive (adjacent) cross-validation over the 1924-1983 period to generate fit statistics for each RMSEminimized model. This differs from the twofold sequential cross-validation usually performed in paleoclimate research 1,50 , which generate reconstructions over a calibration data set and withhold a portion of historic data for model validation. Although the PRISM data set extends back to 1895, it has a well-documented increase in uncertainty before 1924 that makes the use of the 1895-1923 data as a validation data set inappropriate.…”

Section: Methodsmentioning

confidence: 99%

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A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest

Bocinsky

Kohler

2014

Nat Commun

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Section: Methodsmentioning

confidence: 99%

“…Tables 1-17). These four reconstructions are then compared with those produced using the PPR method from the North American Drought Atlas [1][2][3]50 and those produced by ranking chronologies by their marginal correlations with the local climate signal.…”

Section: Methodsmentioning

confidence: 99%

A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest

Bocinsky

Kohler

2014

Nat Commun

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“…The region has experienced several severe droughts in the recent and distant past Cook et al 2010;Touchan et al 2011;Fawcett et al 2011;Oglesby et al 2012). Current climate models forecast an imminent transition to a more arid climate (e.g.…”

Section: Introductionmentioning

confidence: 99%

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

et al. 2013

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The surface air temperature increase in the southwestern United States was much larger during the last few decades than the increase in the global mean. While the global temperature increased by about 0.5°C from 1975 to 2000, the southwestern US temperature increased by about 2°C. If such an enhanced warming persisted for the next few decades, the southwestern US would suffer devastating consequences. To identify major drivers of southwestern climate change we perform a multiple-linear regression of the past 100 years of the southwestern US temperature and precipitation. We find that in the early twentieth century the warming was dominated by a positive phase of the Atlantic multi-decadal oscillation (AMO) with minor contributions from increasing solar irradiance and concentration of greenhouse gases. The late twentieth century warming was about equally influenced by increasing concentration of atmospheric greenhouse gases (GHGs) and a positive phase of the AMO. The current southwestern US drought is associated with a near maximum AMO index occurring nearly simultaneously with a minimum in the Pacific decadal oscillation (PDO) index. A similar situation occurred in mid-1950s when precipitation reached its minimum within the instrumental records. If future atmospheric concentrations of GHGs increase according to the IPCC scenarios (Solomon et al. in Climate change 2007: working group I. The Physical Science Basis, Cambridge, 996 pp, 2007), climate models project a fast rate of southwestern warming accompanied by devastating droughts (Seager et al. in Science 316:1181-1184, 2007 Williams et al. in Nat Clim Chang, 2012). However, the current climate models have not been able to predict the behavior of the AMO and PDO indices. The regression model does support the climate models (CMIP3 and CMIP5 AOGCMs) projections of a much warmer and drier southwestern US only if the AMO changes its 1,000 years cyclic behavior and instead continues to rise close to its 1975-2000 rate. If the AMO continues its quasi-cyclic behavior the US SW temperature should remain stable and the precipitation should significantly increase during the next few decades.

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“…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.…”

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confidence: 99%

“…Increased radiative heating over the tropical Pacific has been shown to enhance the development of La Niña-like conditions that promote drought in the Southwest (4,5,18). It has been suggested that the influence of global warming on the western tropical Pacific and Indian Oceans may already be detectable, and along with cool SSTs in the eastern tropical Pacific, may have been a cause of drought conditions at the turn of the 21st century that affected regions including southwestern North America (19).…”

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confidence: 99%

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

Woodhouse

Meko

MacDonald

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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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...

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Megadroughts in North America: placing IPCC projections of hydroclimatic change in a long‐term palaeoclimate context

Cited by 428 publications

References 77 publications

A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest

A 2,000-year reconstruction of the rain-fed maize agricultural niche in the US Southwest

Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future

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

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