• Worldwide distribution, drivers and tren

    From ScienceDaily@1:317/3 to All on Wed Nov 3 21:30:50 2021
    Worldwide distribution, drivers and trends of sudden droughts

    Date:
    November 3, 2021
    Source:
    University of Oklahoma
    Summary:
    You may know the risks associated with flash floods, but what
    about flash droughts? Flash droughts are described as rapidly
    developing, unexpected periods of drought that can cause severe
    impacts to agricultural and ecological systems and cause ripple
    effects that extend even further.



    FULL STORY ========================================================================== Flash droughts are described as rapidly developing, unexpected periods
    of drought. These flash droughts can cause severe impacts to agricultural
    and ecological systems and cause ripple effects that extend even further.


    ========================================================================== "Given that flash droughts can develop in only a few weeks, they create
    impacts on agriculture that are difficult to prepare for and mitigate,"
    said Jordan Christian, a postdoctoral researcher at the University of
    Oklahoma and the lead author of a study published in the journal Nature Communications. "Even when environmental conditions seem unfavorable
    for rapid drought development, a persistent, multi-week lack of rainfall coupled with hot weather can create flash drought development with its associated impacts.

    "The onset and timing of flash drought is a critical component to
    agricultural impacts, as flash drought can drastically reduce crop
    yields and lead to severe economic losses and potentially disrupt food security," said Jeffrey Basara, an associate professor in both the School
    of Meteorology in the College of Atmospheric and Geographic Sciences and
    the School of Civil Engineering and Environmental Sciences in the Gallogly College of Engineering at OU. "These impacts can have cascading effects, including increased risk for wildfires, depletion of water resources,
    reduction of air quality and decreased food security." Basara, who
    is also the executive associate director of the hydrology and water
    security program at OU, is the principal investigator and Christian's
    faculty adviser. The OU-led study explores the global distribution,
    trends and drivers of flash drought occurrence.

    "Going back into the early 2000s, there was a realization that these
    flash droughts happen," Basara said. "Just as not all droughts are the
    same, some of these droughts evolve much faster than normal.

    "This study is really important because although here in the U.S. we
    can often mitigate some of the effects with irrigation and other tools,
    a number of these types of events happen in places where they can't be mitigated," he added.

    "When that happens in areas dependent on subsistence living, where
    agricultural production is needed to survive, these types of events
    can be really devastating for the local system and create a lot of socioeconomic turmoil." The study identifies global "hotspots" for
    flash drought from 1980 through 2015. Of the 15 locations analyzed,
    eight were identified as having experienced both the most flash drought occurrences for their regions, and as being locations with at least 20%
    of their total land areas used for agricultural production.



    ========================================================================== "What's interesting about flash droughts is they do have some preferential zones around the word," Basara said. "One of the more interesting aspects
    of this particular work is that we were able to start to identify these
    zones. We often associate drought with a lack of rainfall. For these
    flash drought events, about half of the contributing factor is a lack
    of rainfall, the other half is what we call 'hostile layer mass' -- it
    gets really hot and dry." The research team describes these regions as including the "Corn Belt" across the midwestern United States, barley production in the Iberian Peninsula, the wheat belt in western Russia,
    wheat production in Asia Minor, rice-producing regions in India and
    the Indochinese Peninsula, maize production in northeastern China,
    and millet and sorghum production across the Sahel.

    Although six of the 15 regions experienced statistically significant
    increases in flash drought occurrences over the 36-year period examined
    in the study, three of the regions experienced a significant decline in
    flash drought frequency. The reason behind why some regions experienced increased occurrences while others decreased is still unknown.

    "While several regions across the world have seen increasing or decreasing trends in flash drought over the last four decades, it is also critically important to know which regions may become more susceptible to flash
    drought risk in the future," Christian said. "This is especially true in
    areas with agricultural production, as changes in frequency or timing
    of flash drought will create additional challenges during the growing
    season. This study provides a foundation to build off and explore
    key questions regarding future trends of flash drought occurrence."
    Christian added, "When flash drought events were examined, one thing was
    clear -- timing is everything in terms of impacts from these events."
    In 2019, Christian and Basara developed a method to begin to identify
    flash droughts. That methodology has helped researchers begin to better understand these events.



    ========================================================================== "When I entered the Ph.D. program in 2017, Dr. Jeff Basara and I had
    a conversation about a research topic for my dissertation and he said,
    'I have an idea regarding flash droughts,'" explained Christian. "That
    idea translated into the creation of a method to identify flash drought,
    the investigation of several flash drought events, and ultimately led
    to the global analysis of flash drought. It turned out to be a pretty
    good idea." Christian led a study published in Environmental Research
    Letters in 2020 that looked at the impact of a major heatwave in Russia
    in 2010. Preceding that heatwave was a flash drought. The impact of
    those weather events led to the decimation of Russia's wheat crop,
    so much so that Russia stopped exporting.

    "Russia's biggest wheat importer were countries in the Middle East,
    so the price of grain went through the roof in the Middle East," Basara
    said. "The social unrest of the Arab Spring was created, in part, because
    of the unusually high grain prices and the socioeconomic turmoil those
    prices caused. That ripple effect was caused by a flash drought in one
    part of the work that affected an entirely other portion of the world."
    With this study, the researchers are expanding their understanding of
    where flash droughts are more likely to occur around the world.

    "This study helps us understand where they're happening, but now we need
    to understand more about the why," he said. "We see that depending on
    where you are in the globe, the mechanisms are a bit different from one
    place to another.

    "As we go into a changing climate system, as we have population
    growth and food security issues, this becomes one of those
    topics that's important because of its really severe impact on
    agriculture and water resources," he added. "It has cascading
    impacts like wildfires and more. If we can better understand
    these flash droughts, we might have a better understanding of their predictability and then we can better plan for these types of events." ========================================================================== Story Source: Materials provided by University_of_Oklahoma. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Christian, J.I., Basara, J.B., Hunt, E.D. et al. Global
    distribution,
    trends, and drivers of flash drought occurrence. Nat Commun,
    2021 DOI: 10.1038/s41467-021-26692-z ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/11/211103105026.htm

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