El Nino and La Nina patterns linked to synchronized global droughts and floods: Study

The recurring Pacific Ocean climate patterns known as El Nino and La Nina have played a dominant role in driving simultaneous droughts and floods across continents over the past two decades, according to new research covered by media outlets on Tuesday.

Published in AGU Advances, the research says the El Nino-Southern Oscillation (ENSO) is the primary force behind extreme changes in total water storage globally since 2002.

"Looking at the global scale, we can identify what areas are simultaneously wet or simultaneously dry," said study co-author Bridget Scanlon from the University of Texas at Austin.

"That of course affects water availability, food production, food trade, all of these global things," Science Daily quoted her as saying.

The team used satellite gravity measurements from NASA's GRACE and GRACE Follow-On (GRACE-FO) missions to estimate total water storage, encompassing rivers, lakes, soil moisture, ice, and groundwater.

Lead author Ashraf Rateb explained the importance of tracking spatial patterns, saying that "extremes are rare," but their global connections can offer greater insight into the dynamics of floods and droughts.

The findings highlighted ENSO's ability to trigger extreme conditions in distant regions at the same time.

For example, El Nino in the mid-2000s aligned with drought in South Africa, and another El Nino in 2015-2016 coincided with Amazon dryness. Conversely, La Nina in 2010-2011 brought intense rainfall to Australia, Brazil, and South Africa.

The study also found a shift around 2011-2012: before this period, wet extremes were more common, but since then, dry extremes have dominated, a change attributed to a persistent Pacific climate pattern.

"These data really capture the rhythm of big climate cycles," said NASA's JT Reager, emphasizing how events in the Pacific Ocean can affect global water security.

Scanlon added: "We're not just running out of water, we're managing extremes. And that's a very different message."