• Flash droughts present a new challenge for subseasonal-to-seasonal prediction

      Pendergrass, Angeline G.; Meehl, Gerald A.; Pulwarty, Roger; Hobbins, Mike; Hoell, Andrew; AghaKouchak, Amir; Bonfils, Céline J. W.; Gallant, Ailie J. E.; Hoerling, Martin; Hoffmann, David; et al. (NATURE PUBLISHING GROUP, 2020-03)
      Flash droughts, which develop over the course of weeks, are difficult to forecast given the current state of subseasonal-to-seasonal prediction. This Perspective offers operational and research definitions, places them in the broader context of climate and suggests avenues for future research. Flash droughts are a recently recognized type of extreme event distinguished by sudden onset and rapid intensification of drought conditions with severe impacts. They unfold on subseasonal-to-seasonal timescales (weeks to months), presenting a new challenge for the surge of interest in improving subseasonal-to-seasonal prediction. Here we discuss existing prediction capability for flash droughts and what is needed to establish their predictability. We place them in the context of synoptic to centennial phenomena, consider how they could be incorporated into early warning systems and risk management, and propose two definitions. The growing awareness that flash droughts involve particular processes and severe impacts, and probably a climate change dimension, makes them a compelling frontier for research, monitoring and prediction.
    • Increased costs to US pavement infrastructure from future temperature rise

      Underwood, B. Shane; Guido, Zack; Gudipudi, Padmini; Feinberg, Yarden; Univ Arizona, Inst Environm (NATURE PUBLISHING GROUP, 2017-10)
      Roadway design aims to maximize functionality, safety, and longevity(1,2). The materials used for construction, however, are often selected on the assumption of a stationary climate(1,3). Anthropogenic climate change may therefore result in rapid infrastructure failure and, consequently, increased maintenance costs, particularly for paved roads where temperature is a key determinant for material selection. Here, we examine the economic costs of projected temperature changes on asphalt roads across the contiguous United States using an ensemble of 19 global climate models forced with RCP 4.5 and 8.5 scenarios. Over the past 20 years, stationary assumptions have resulted in incorrect material selection for 35% of 799 observed locations. With warming temperatures, maintaining the standard practice for material selection is estimated to add approximately US$13.6, US$19.0 and US$21.8 billion to pavement costs by 2010, 2040 and 2070 under RCP4.5, respectively, increasing to US$14.5, US$26.3 and US$35.8 for RCP8.5. These costs will disproportionately affect local municipalities that have fewer resources to mitigate impacts. Failing to update engineering standards of practice in light of climate change therefore significantly threatens pavement infrastructure in the United States.