Sep 19, 2018

Recent intensification of Amazon flooding extremes driven by strengthened Walker circulation

Jonathan Barichivich, Emanuel Gloor, Philippe Peylin, Roel J. W. Brienen, Jochen Schöngart, Jhan Carlo Espinoza, Kanhu C. Pattnayak
Science Advances
  • States that although the variability of the Amazon hydrological cycle has been increasing since the late 1990s, its underlying causes have remained elusive
  • Uses water levels in the Amazon River to quantify changes in extreme events and then analyze their cause
  • Finds that:
    • Despite continuing research emphasis on droughts, the largest change over recent decades is a marked increase in very severe floods
    • Increased flooding is linked to a strengthening of the Walker circulation, resulting from strong tropical Atlantic warming and tropical Pacific cooling
    • Atlantic warming due to combined anthropogenic and natural factors has contributed to enhance the change in atmospheric circulation
  • Concludes that whether this anomalous increase in flooding will last depends on the evolution of the tropical inter-ocean temperature difference