The influence of greenhouse gases on the 1930s Dust Bowl heat waves across central United States

2020 ◽  
Author(s):  
Sabine Undorf ◽  
Tim Cowan ◽  
Gabi Hegerl ◽  
Luke Harrington ◽  
Friederike Otto
Keyword(s):  
United States ◽  
New York ◽  
Greenhouse Gas ◽  
Heat Wave ◽  
Heat Waves ◽  
Dust Storms ◽  
Dust Bowl ◽  
Regional Modelling ◽  
Surface Warming ◽  
Central United States

<p>The central United States experienced the hottest summers of the twentieth century in 1934 and 1936, with over 40 heat wave days and maximum temperatures surpassing 44°C at some locations like Kansas and Oklahoma. In fact, as of 2019, the summer of 1936 is still the hottest on record. The heat waves coincided with the decade-long Dust Bowl drought, that caused wide-spread crop failures, dust storms that penetrated to New York and considerable out-migration. In a very-large ensemble regional modelling framework, we show that greenhouse gas increases slightly enhanced the frequency and duration of the Dust Bowl heat waves, and would strongly enhance similar heat waves in the present day under current, further elevated greenhouse gas levels. Specifically, present-day atmospheric greenhouse gas forcing would reduce the return period of a rare (less than once in a century) heat wave summer as observed in 1936 to about 1-in 40-years, with further contribution by sea surface warming. Here, we show that a key driver of this elevated heat wave risk is the reduction in evaporative cooling and increase in sensible heating during dry springs and summers.  Hence, we conclude that a warmer world is creating the potential for future extreme heat in moisture-limited regions, with potentially very damaging impacts.</p>

scholarly journals Factors Contributing to Record-Breaking Heat Waves over the Great Plains during the 1930s Dust Bowl

2017 ◽  
Vol 30 (7) ◽  
pp. 2437-2461 ◽  
Author(s):  
Tim Cowan ◽  
Gabriele C. Hegerl ◽  
Ioana Colfescu ◽  
Massimo Bollasina ◽  
Ariaan Purich ◽  
...  
Keyword(s):  
United States ◽  
Heat Wave ◽  
Great Plains ◽  
Land Surface ◽  
Heat Waves ◽  
Circulation Pattern ◽  
Dust Bowl ◽  
Warm Advection ◽  
Summer Heat ◽  
Upper Level

Record-breaking summer heat waves were experienced across the contiguous United States during the decade-long “Dust Bowl” drought in the 1930s. Using high-quality daily temperature observations, the Dust Bowl heat wave characteristics are assessed with metrics that describe variations in heat wave activity and intensity. Despite the sparser station coverage in the early record, there is robust evidence for the emergence of exceptional heat waves across the central Great Plains, the most extreme of which were preconditioned by anomalously dry springs. This is consistent with the entire twentieth-century record: summer heat waves over the Great Plains develop on average ~15–20 days earlier after anomalously dry springs, compared to summers following wet springs. Heat waves following dry springs are also significantly longer and hotter, indicative of the importance of land surface feedbacks in heat wave intensification. A distinctive anomalous continental-wide circulation pattern accompanied exceptional heat waves in the Great Plains, including those of the Dust Bowl decade. An anomalous broad surface pressure ridge straddling an upper-level blocking anticyclone over the western United States forced substantial subsidence and adiabatic warming over the Great Plains, and triggered anomalous southward warm advection over southern regions. This prolonged and amplified the heat waves over the central United States, which in turn gradually spread westward following heat wave emergence. The results imply that exceptional heat waves are preconditioned, triggered, and strengthened across the Great Plains through a combination of spring drought, upper-level continental-wide anticyclonic flow, and warm advection from the north.

scholarly journals An Analysis of the Prevalence of Heat Waves in the United States between 1948 and 2015

2018 ◽  
Vol 57 (7) ◽  
pp. 1535-1549 ◽  
Author(s):  
Evan M. Oswald
Keyword(s):  
United States ◽  
Heat Wave ◽  
Great Plains ◽  
Heat Waves ◽  
Estimation Method ◽  
The United States ◽  
Northern Great Plains ◽  
Strong Increase ◽  
Climate Data ◽  
Nighttime Temperatures

AbstractUnusually hot weather is a major concern to public health as well as other systems (e.g., ecological, economical, energy). This study utilized spatially continuous and homogenized observational surface climate data to examine changes in the regularity of heat waves in the continental United States. This included the examination of heat waves according only to daytime temperatures, nighttime temperatures, and both daytime and nighttime temperatures. Results confirmed a strong increase in the prevalence of heat waves between the mid-1970s and the dataset end (2015), and that increase was preceded by a mild decrease since the dataset beginning (1948). Results were unclear whether the prevalence of nighttime or simultaneous daytime–nighttime heat waves increased the most, but it was clear that increases were largest in the summer. The largest gains occurred in the West and Southwest, and a “warming hole” was most conspicuous in the northern Great plains. The changes in heat wave prevalence were similar to changes in the mean temperatures, and more so in the daytime heat waves. Daytime and nighttime heat waves coincided with one another more frequently in recent years than they did in the 1970s. Some parts of the United States (West Coast) were more likely than other parts to experience daytime and nighttime heat waves simultaneously. While linear trends were not sensitive to the climate dataset, trend estimation method, or heat wave definition, they were mildly sensitive to the start and end dates and extremely sensitive to the climate base period method (fixed in time or directly preceding any given heat wave).

scholarly journals New York City Impacts on a Regional Heat Wave

2018 ◽  
Vol 57 (4) ◽  
pp. 837-851 ◽  
Author(s):  
Luis E. Ortiz ◽  
Jorge E. Gonzalez ◽  
Wei Wu ◽  
Martin Schoonen ◽  
Jeffrey Tongue ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Heat Wave ◽  
Cross Sections ◽  
York City ◽  
Heat Waves ◽  
Wrf Model ◽  
Positive Interactions ◽  
Synoptic Conditions ◽  
Energy And Momentum

ABSTRACTHeat waves are projected to increase in magnitude and frequency throughout this century because of increasing global temperatures, making it critically important to acquire improved understanding of their genesis and interactions with large cities. This study presents an application of the method of factor separation to assess combined impacts of a synoptic-scale heat wave, urban land cover, and urban energy and momentum fluxes on temperatures and winds over New York City, New York, via use of high-resolution simulations (1-km grid spacing) with an urbanized version of the Weather Research and Forecasting (WRF) Model. Results showed that factors behaved different throughout the day, with synoptic conditions dominating afternoon temperature contributions (>7°C). At night, combined urban surface factors contributed over 5°C during the heat wave and up to 1.5°C on non-heat-wave days. Positive interactions among all factors during morning and nighttime indicate an amplification of the urban heat island of up to 4°C during the heat wave. Midtown Manhattan vertical cross sections, where urban canopies are most dense, showed a change in the sign (from positive to negative) of the contribution of the urban fluxes between night and day below 500 m, possibly as a result of decreased radiative cooling from trapping by buildings and increased thermal storage by buildings as well as frictional effects that oppose the incoming warm air.

Mechanisms Associated with Daytime and Nighttime Heat Waves over the Contiguous United States

2020 ◽  
Vol 59 (11) ◽  
pp. 1865-1882
Author(s):  
Natalie P. Thomas ◽  
Michael G. Bosilovich ◽  
Allison B. Marquardt Collow ◽  
Randal D. Koster ◽  
Siegfried D. Schubert ◽  
...  
Keyword(s):  
United States ◽  
Human Health ◽  
Heat Wave ◽  
Heat Waves ◽  
The United States ◽  
Daily Maximum ◽  
Local Threshold ◽  
Dry Conditions ◽  
Heat And Moisture ◽  
Climate Events

AbstractHeat waves are extreme climate events that have the potential to cause immense stress on human health, agriculture, and energy systems, so understanding the processes leading to their onset is crucial. There is no single accepted definition for heat waves, but they are generally described as a sustained amount of time over which temperature exceeds a local threshold. Multiple different temperature variables are potentially relevant, because high values of both daily maximum and minimum temperatures can be detrimental to human health. In this study, we focus explicitly on the different mechanisms associated with summertime heat waves manifested during daytime hours versus nighttime hours over the contiguous United States. Heat waves are examined using the National Aeronautics and Space Administration Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Over 1980–2018, the increase in the number of heat-wave days per summer was generally stronger for nighttime heat-wave days than for daytime heat-wave days, with localized regions of significant positive trends. Processes linked with daytime and nighttime heat waves are identified through composite analysis of precipitation, soil moisture, clouds, humidity, and fluxes of heat and moisture. Daytime heat waves are associated with dry conditions, reduced cloud cover, and increased sensible heating. Mechanisms leading to nighttime heat waves differ regionally across the United States, but they are typically associated with increased clouds, humidity, and/or low-level temperature advection. In the midwestern United States, enhanced moisture is transported from the Gulf of Mexico during nighttime heat waves.

scholarly journals Fatalities Associated with Nonconvective High-Wind Events in the United States

2008 ◽  
Vol 47 (2) ◽  
pp. 717-725 ◽  
Author(s):  
Walker S. Ashley ◽  
Alan W. Black
Keyword(s):  
United States ◽  
The United States ◽  
Dust Storms ◽  
Extratropical Cyclones ◽  
High Wind ◽  
Central United States ◽  
Wind Events ◽  
Gap Winds ◽  
Social Vulnerabilities ◽  
High Winds

Abstract A database was compiled for the period 1980–2005 to assess the threat to life in the conterminous United States from nonconvective high-wind events. This study reveals the number of fatalities from these wind storms, their cause, and their unique spatial distributions. While tornadoes continue to cause the most wind-related fatalities per year, nonconvective high winds (defined as phenomena such as downslope and gap winds, gradient winds, dust storms, and winds associated with midlatitude cyclones) have the potential to fatally injure more people than thunderstorm or hurricane winds. Nonconvective wind fatalities occur more frequently in vehicles or while boating. Fatalities are most common along the West Coast and Northeast in association with passing extratropical cyclones, with fewer fatalities observed in the central United States despite this region’s susceptibility for high-wind gusts. A combination of physical and social vulnerabilities is suggested as the cause for the unique fatality distribution found. More than 83% of all nonconvective wind fatalities are associated with the passage of extratropical cyclones.

scholarly journals Regional Climate Model Projections and Uncertainties of U.S. Summer Heat Waves

2010 ◽  
Vol 23 (16) ◽  
pp. 4447-4458 ◽  
Author(s):  
Kenneth E. Kunkel ◽  
Xin-Zhong Liang ◽  
Jinhong Zhu
Keyword(s):  
United States ◽  
Regional Climate Model ◽  
Heat Wave ◽  
General Circulation ◽  
Climate Model ◽  
Heat Waves ◽  
Regional Climate ◽  
General Circulation Models ◽  
Threshold Temperature ◽  
Wave Characteristics

Abstract Regional climate model (RCM) simulations, driven by low and high climate-sensitivity coupled general circulation models (CGCMs) under various future emissions scenarios, were compared to projected changes in heat wave characteristics. The RCM downscaling reduces the CGCM biases in heat wave threshold temperature by a factor of 2, suggesting a higher credibility in the future projections. All of the RCM simulations suggest that there is a high probability of heat waves of unprecedented severity by the end of the twenty-first century if a high emissions path is followed. In particular, the annual 3-day heat wave temperature increases generally by 3°–8°C; the number of heat wave days increases by 30–60 day yr−1 over much of the western and southern United States with slightly smaller increases elsewhere; the variance spectra for intermediate, 3–7 days (prolonged, 7–14 days), temperature extremes increase (decrease) in the central (western) United States. If a lower emissions path is followed, then the outcomes range from quite small changes to substantial increases. In all cases, the mean temperature climatological shift is the dominant change in heat wave characteristics, suggesting that adaptation and acclimatization could reduce effects.

scholarly journals Resolving the Dust Bowl paradox of grassland responses to extreme drought

2020 ◽  
Vol 117 (36) ◽  
pp. 22249-22255 ◽  
Author(s):  
Alan K. Knapp ◽  
Anping Chen ◽  
Robert J. Griffin-Nolan ◽  
Lauren E. Baur ◽  
Charles J.W. Carroll ◽  
...  
Keyword(s):  
United States ◽  
High Temperatures ◽  
Climate Extremes ◽  
Extreme Drought ◽  
Dust Bowl ◽  
Strongly Coupled ◽  
Precipitation Seasonality ◽  
Central United States ◽  
Use Efficiency

During the 1930s Dust Bowl drought in the central United States, species with the C3photosynthetic pathway expanded throughout C4-dominated grasslands. This widespread increase in C3grasses during a decade of low rainfall and high temperatures is inconsistent with well-known traits of C3vs. C4pathways. Indeed, water use efficiency is generally lower, and photosynthesis is more sensitive to high temperatures in C3than C4species, consistent with the predominant distribution of C3grasslands in cooler environments and at higher latitudes globally. We experimentally imposed extreme drought for 4 y in mixed C3/C4grasslands in Kansas and Wyoming and, similar to Dust Bowl observations, also documented three- to fivefold increases in C3/C4biomass ratios. To explain these paradoxical responses, we first analyzed long-term climate records to show that under nominal conditions in the central United States, C4grasses dominate where precipitation and air temperature are strongly related (warmest months are wettest months). In contrast, C3grasses flourish where precipitation inputs are less strongly coupled to warm temperatures. We then show that during extreme drought years, precipitation–temperature relationships weaken, and the proportion of precipitation falling during cooler months increases. This shift in precipitation seasonality provides a mechanism for C3grasses to respond positively to multiyear drought, resolving the Dust Bowl paradox. Grasslands are globally important biomes and increasingly vulnerable to direct effects of climate extremes. Our findings highlight how extreme drought can indirectly alter precipitation seasonality and shift ecosystem phenology, affecting function in ways not predictable from key traits of C3and C4species.

scholarly journals Flash Drought as Captured by Reanalysis Data: Disentangling the Contributions of Precipitation Deficit and Excess Evapotranspiration

2019 ◽  
Vol 20 (6) ◽  
pp. 1241-1258 ◽  
Author(s):  
R. D. Koster ◽  
S. D. Schubert ◽  
H. Wang ◽  
S. P. Mahanama ◽  
Anthony M. DeAngelis
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Extreme Precipitation ◽  
Land Surface ◽  
Heat Waves ◽  
Reanalysis Data ◽  
Land System ◽  
Central United States ◽  
Surface Drying

Abstract Flash droughts—uncharacteristically rapid dryings of the land system—are naturally associated with extreme precipitation deficits. Such precipitation deficits, however, do not tell the whole story, for land surface drying can be exacerbated by anomalously high evapotranspiration (ET) rates driven by anomalously high temperatures (e.g., during heat waves), anomalously high incoming radiation (e.g., from reduced cloudiness), and other meteorological anomalies. In this study, the relative contributions of precipitation and ET anomalies to flash drought generation in the Northern Hemisphere are quantified through the analysis of diagnostic fields contained within the MERRA-2 reanalysis product. Unique to the approach is the explicit treatment of soil moisture impacts on ET through relationships diagnosed from the reanalysis data; under this treatment, an ET anomaly that is negative relative to the local long-term climatological mean is still considered positive in terms of its contribution to a flash drought if it is high for the concurrent value of soil moisture. Maps produced in the analysis show the fraction of flash drought production stemming specifically from ET anomalies and illustrate how ET anomalies for some droughts are related to temperature and radiation anomalies. While ET is found to have an important impact on flash drought production in the central United States and in parts of Russia known from past studies to be prone to heat wave–related drought, and while this impact does appear stronger during the onset (first several days) of flash droughts, overall the contribution of ET to these droughts is small relative to the contribution of precipitation deficit.

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