JUL 30, 2019 2:16 PM PDT

Our past megadroughts, and what's to come

Do you think the droughts we suffer from now are bad? Centuries ago the American Southwest was plagued with approximately twelve megadroughts that each lasted for decades. From the 9th century throughout the 15th century these droughts took over local climate – but what caused them? Scientists from Columbia University's Lamont-Doherty Earth Observatory aim to answer that question in new research published recently in the journal Science Advances. They hope that their findings will help us better understand the risk that megadroughts pose for our future in our warming planet.

The scientists on the study reconstructed aquatic climate data from the Paleo Hydrodynamics Data Assimilation product and looked at estimates of radiative forcing in order to determine three interacting causes behind the megadroughts. (Radiative forcing refers to when the Earth absorbs more sunlight than it radiates back into space. Both radiative forcing and ocean temperatures were found to be significant factors in triggering the megadroughts of the past.)

The authors reported the following three factors as triggers for megadroughts: “unusually frequent and cold central tropical Pacific sea surface temperature (SST) excursions in conjunction with anomalously warm Atlantic SSTs and a locally positive radiative forcing.”

The authors say that the first factor, unusually frequent and cold central tropical Pacific sea surface temperatures, refers to La Niña events, and is thought to be more than twice as important in causing the megadroughts. An increase seen in heat as a result of high radiative forcing caused greater evaporation, which was exacerbated by warm conditions in the Atlantic.

Are megadroughts lurking in our future? Photo: Pixabay

Although the information the team gathered is more precise than previous studies, the future of megadroughts in our changing climate is still uncertain. A lot of it will depend on future El Niño and La Niña activity, of which there are still poor models, explain the authors. But, they caution, glocal warming sure won’t make the situation better.

"Because you increase the baseline aridity, in the future when you have a big La Niña, or several of them in a row, it could lead to megadroughts in the American West," commented lead author Nathan Steiger, a Lamont-Doherty Earth Observatory hydroclimatologist. Steiger and his team hopes to continue their investigation of past megadroughts in order to prepare us better for what may lie ahead.

Sources: Science Daily, Science Advances

About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
DEC 09, 2019
Genetics & Genomics
DEC 09, 2019
Researchers Rewire E. coli to Consume Carbon Dioxide
Milo et. al.   Researchers have genetically rewired the metabolism of Escherichia coli to be autotrophic, using formate (COOH) as a food sou...
DEC 19, 2019
Earth & The Environment
DEC 19, 2019
Tiny Fossils Reveal California's Ocean Acidification History
A century’s worth of microscopic shells has revealed that ocean acidification is occurring in California waters at twice the rate of the global avera...
DEC 23, 2019
Plants & Animals
DEC 23, 2019
Brave Ant Explorers Engage a Termite Colony
Ants and termites have known their place as bitter rivals in the animal kingdom for more than 150 million years. Even today, as populations peak at some of...
JAN 11, 2020
Earth & The Environment
JAN 11, 2020
The Ganges rising: water levels in the delta
A study published recently in PNAS reports the future of water-level rise in the Ganges-Brahmaputra-Meghna delta. A collaboration of researchers from the C...
JAN 17, 2020
Earth & The Environment
JAN 17, 2020
What's the carbon footprint of your fish stick?
New research from scientists at the University of California, Santa Cruz highlights the unsustainable footprint of the processed fish industry. The study, ...
FEB 12, 2020
Earth & The Environment
FEB 12, 2020
Urban Heat-Islands Mistakenly Signal Spring to Trees
Have you noticed trees and other vegetation in your city turning green earlier than usual? A new study from Iowa State University has shown that urban land...
Loading Comments...