Unprecedented 21st century drought risk in the American Southwest and Central Plains

Cook, Benjamin I.; Ault, Toby R.; Smerdon, Jason E.

doi:10.1126/sciadv.1400082

Cited by 1,225 publications

(1,048 citation statements)

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“…S12). This result is consistent with a systematic examination of Coupled Model Intercomparison Project 5 (CMIP5) simulations (38), although the uncertainties in soil moisture projections are large (38). If soil moisture is not the limiting factor, surface ozone will be affected by VPD-regulated biogenic isoprene emissions and it is expected to increase in the future on the basis of the GFDL model projections.…”

Section: Resultssupporting

confidence: 73%

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

Zhang

Wang

2016

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

110

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Ground-level ozone is adverse to human and vegetation health. High ground-level ozone concentrations usually occur over the United States in the summer, often referred to as the ozone season. However, observed monthly mean ozone concentrations in the southeastern United States were higher in October than July in 2010. The October ozone average in 2010 reached that of July in the past three decades . Our analysis shows that this extreme October ozone in 2010 over the Southeast is due in part to a dry and warm weather condition, which enhances photochemical production, air stagnation, and fire emissions. Observational evidence and modeling analysis also indicate that another significant contributor is enhanced emissions of biogenic isoprene, a major ozone precursor, from water-stressed plants under a dry and warm condition. The latter finding is corroborated by recent laboratory and field studies. This climate-induced biogenic control also explains the puzzling fact that the two extremes of high October ozone both occurred in the 2000s when anthropogenic emissions were lower than the 1980s and 1990s, in contrast to the observed decreasing trend of July ozone in the region. The occurrences of a drying and warming fall, projected by climate models, will likely lead to more active photochemistry, enhanced biogenic isoprene and fire emissions, an extension of the ozone season from summer to fall, and an increase of secondary organic aerosols in the Southeast, posing challenges to regional air quality management.ground-level ozone | ozone season | regional climate change | isoprene | air quality G round-level ozone is a pollutant harmful to human and vegetation health (1, 2). High ground-level ozone events are typically found in the summer when the formation of ozone is active through photochemical reactions involving nitrogen oxides (NO x = NO + NO 2 ) and volatile organic compounds (VOCs). However, ozone concentrations are sensitive to weather and climate (3-8), and the high-ozone season could extend beyond summer in the future (9-13). Previous climate-chemistry model studies have estimated the change of ground-level ozone (ΔO 3 ) in the United States resulting only from meteorological changes. Their results show large variation in the sign and magnitude of ΔO 3 in the fall, especially over forested regions such as the southeastern United States (SE) (10, 13). The lack of consensus reflects the uncertainties in modeling regional climate change and the consequent response of ground-level ozone.In this study, we focus on analyzing the historical ozone records. Fig. 1A Fig. S1). The number increases to 324 exceedances at 112 stations if the new US ambient ozone standard threshold value, 70 ppbv, is used (SI Appendix, Fig. S1). The regional average reached 65 ppbv during October 8-10, 2010 ( Fig. 2A). ppbv, considerably lower than that in the summer ozone season (∼50 ppbv in July). However, in the two extreme years, 2000 and 2010, regional monthly mean [O 3 ] MDA8 are 52 and 49 ppbv, respectively, two interannual standa...

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Section: Resultssupporting

confidence: 73%

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

Zhang

Wang

2016

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

110

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“…Dado que supuestamente no se realizó dicha definición, ante las prospectivas de un siglo xxi seco (Cook, Ault y Smerdon, 2015) el tema se vuelve importante en función de una necesaria cooperación binacional. Ante ello se han generado gran cantidad de textos con el fin de que ambos países propicien medidas alternativas ante una condición de la naturaleza que parece irremediable: el cambio climático y sus consecuencias en los procesos productivos, el abasto urbano, la producción de energía eléctrica, la pesca y su relación con la conservación del medio ambiente (Christensen y Lettenmaier, 2006).…”

Section: Introductionunclassified

La variabilidad histórica de la corriente del Río Colorado. El vínculo con la minuta 319

López¹

2017

REF

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Esta obra está protegida bajo una Licencia Creative Commons Atribución-NoComercial 4.0 Internacional. e-ISSN 2395-9134Estudios Fronterizos, 18(37) septiembre-diciembre de 2017, pp. ResumenEl propósito de este artículo es analizar los efectos de la variabilidad histórica de la corriente del río Colorado y cómo se ha utilizado dicha variabilidad en las discusiones para el control y administración de la mencionada cuenca internacional. Con base en el análisis de estudios realizados por diversos ingenieros, abogados y políticos estadounidenses, demostramos que desde principios del siglo xx se sabía de esta variabilidad. Específicamente se busca explicar el significado y consecuencias que tuvo el tema de la variabilidad en la minuta 319, firmada por la Comisión Internacional de Límites y Aguas (International Border and Water Commission), donde por primera ocasión se contempla de manera explícita el cambio climático, dado que diversos sectores han insistido en profundizar en el tema de definir "sequía extraordinaria", argumentando que una cuota fija a México no tomó en cuenta el factor de cambio climático.Palabras clave: cuenca transfronteriza, zona sísmica, cooperación-conflicto, variabilidad. AbstractThe purpose of this article is to analyze the effects of the historical variability of the Colorado River current and how this variability has been used in the discussions for the control and administration of the mentioned international basin. Based on the analysis of studies carried out by various us engineers, lawyers and politicians, we have shown that since the beginning of the 20th century this variability was known. Specifically, it seeks to explain the meaning and consequences of the issue of variability in minutes 319, signed by the International Boundary and Water Commission, where for the first time, since several sectors have insisted on deepening the issue of defining "extraordinary gear", arguing that a fixed quota for Mexico did not take into account the climate change factor.

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“…Both historic and pre-instrumental record droughts have had notable effects on vegetation patterns, with concomitant changes in patterns of human habitation and social interaction (Woodhouse 2004;Benson et al 2007). The possibility of future droughts that exceed the most severe droughts of the past millennia cannot be excluded (Cook et al 2015). These observations have heightened concern about the potential for future harm to species and ecosystems as well as people and their livelihoods under changing climatic conditions.…”

Section: Introductionmentioning

confidence: 99%

Triangulation in climate change vulnerability assessment: examples from Colorado, USA

2017

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Climate change vulnerability assessment is a key first step for land managers attempting to address the potential impacts of future climatic conditions on important vegetation types. We compared outcomes of three vulnerability assessments focused on major vegetation types in Colorado. Assessments differed in methods and scale, but overlapped in both qualitative and quantitative techniques, and in vegetation types assessed. Agreement on vegetation type vulnerability was 47-50% between the regional scale southwestern Colorado assessment and either of two statewide assessments. Disagreements were due to regional sampling bias, qualitative vs. quantitative climate exposure analysis, or lack of information about the vegetation type in question. The two statewidescale assessments were in agreement on 75% of vegetation types assessed in both studies; differences were due to choice and interpretation of climate projection data. Sources of variation are categorized in relation to a taxonomy of uncertainty. We compare our iterative experience of climate change vulnerability assessment using methods adapted to the needs and means of various land management agencies to the technique of triangulation used to gradually home in on the location of an object. We clarify ways in which participant choices shape the end result and mitigate the common perception that climate science is too difficult for the lay person to use or understand.

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Unprecedented 21st century drought risk in the American Southwest and Central Plains

Abstract: Evidence suggests that Western North America will be drier at the end of the 21st century than any period of the last 1000 years.

Cited by 1,225 publications

References 32 publications

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

La variabilidad histórica de la corriente del Río Colorado. El vínculo con la minuta 319

Triangulation in climate change vulnerability assessment: examples from Colorado, USA

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