Nav: Home

Indian Ocean causes drought and heatwaves in South America

July 08, 2019

New research has found the record-breaking South American drought of 2013/14 with its succession of heatwaves and long lasting marine heatwave had its origins in a climate event half a world away - over the Indian Ocean.

The findings published in Nature Geoscience by an international research team with authors from the Federal University of Santa Catarina in Brazil, Australia's ARC Centre of Excellence for Climate Extremes and NOAA in the US suggest this may not have been the first time the Indian Ocean has brought extraordinary heat to the region.

It all started with strong atmospheric convection over the Indian Ocean that generated a powerful planetary wave that travelled across the South Pacific to the South Atlantic where it displaced the normal atmospheric circulation over South America.

You can think of these atmospheric waves as being similar to an ocean swell generated by strong winds that travel thousands of kilometres from where they were generated. Large-scale atmospheric planetary waves form when the atmosphere is disturbed and this disturbance generates waves that travel around the planet.

"The atmospheric wave produced a large area of high pressure, known as a blocking high, that stalled off the east coast of Brazil," said lead author Dr Regina Rodrigues.

"The impacts of the drought that followed were immense and prolonged, leading to a tripling of dengue fever cases, water shortages in São Paulo, and reduced coffee production that led to global shortages and worldwide price increases."

That impact wasn't just felt on land as the high-pressure system stalled over the ocean.

"Highs are associated with good weather. This means clear skies - so more solar energy going into the ocean - and low winds - so less ocean cooling from evaporation."

"The result of this blocking high was an unprecedented marine heatwave that amplified the unusual atmospheric conditions and likely had an impact on local fisheries in the region."

The researchers found this atmospheric wave was not an isolated event and that strong convection far away in the Indian Ocean had previously led to drought impacts in South America.

"Using observations from 1982 to 2016, we noticed an increase not only in frequency but also in duration, intensity and area of these marine heatwave events. For instance, on average these events have become 18 days longer, 0.05°C warmer and 7% larger per decade." said CLEX co-author Dr Andrea Taschetto.

The 2013/14 South American drought and marine heatwave is the latest climate case study to show how distant events in one region can have major climate impacts on the other side of the world.

"Researchers found that Australia's 2011 Ningaloo Nino in the Indian Ocean, which completely decimated coastal ecosystems and impacted fisheries, was caused by a La Niña event in the tropical Pacific," said Australian co-author Dr Alex Sen Gupta.

"Here we have yet another example of how interconnected our world is. Ultimately, our goal is to understand and use these complex remote connections to provide some forewarning of high impact extreme events around the world."
-end-
For further information or to arrange interviews contact:

Alvin Stone (for Dr Andrea Taschetto and Dr Alex Sen Gupta).
Media and Communications Manager for ARC Centre of Excellence for Climate Extremes.
Email: alvin.stone@unsw.edu.au. Phone: +61 418 617 366.

Dr Regina Rodrigues
regina.rodrigues@ufsc.br
Phone: 55-48-3721-3530
Mobile: 55-48-99640-0554

University of New South Wales

Related Drought Articles:

Vinegar: A cheap and simple way to help plants fight drought
Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) have discovered a new, yet simple, way to increase drought tolerance in a wide range of plants.
Lending plants a hand to survive drought
A research team led by the Australian National University has found a new way to help plants better survive drought by enhancing their natural ability to preserve water.
New rice fights off drought
Scientists at the RIKEN Center for Sustainable Resource Science (CSRS) have developed strains of rice that are resistant to drought in real-world situations.
Drought linked with human health risks in US analysis
A Yale-led analysis of health claims in 22 US states found that severe drought conditions increased the risk of mortality -- and, in some cases, cardiovascular disease -- among adults 65 or over.
A basis for the application of drought indices in China
The definition of a drought index is the foundation of drought research.
Under the Dead Sea, warnings of dire drought
Nearly 1,000 feet below the bed of the Dead Sea, scientists have found evidence that during past warm periods, the Mideast has suffered drought on scales never recorded by humans -- a possible warning for current times.
Forests worldwide threatened by drought
Forests around the world are at risk of death due to widespread drought, University of Stirling researchers have found.
How much drought can a forest take?
Why do some trees die in a drought and others don't?
Pressures from grazers hastens ecosystem collapse from drought
Ecosystem collapse from extreme drought can be significantly hastened by pressures placed on drought-weakened vegetation by grazers and fungal pathogens, a new Duke-led study finds.
Molecular conductors help plants respond to drought
Salk scientists find key players in complex plant response to stress, offering clues to coping with drier conditions.

Related Drought Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#530 Why Aren't We Dead Yet?
We only notice our immune systems when they aren't working properly, or when they're under attack. How does our immune system understand what bits of us are us, and what bits are invading germs and viruses? How different are human immune systems from the immune systems of other creatures? And is the immune system so often the target of sketchy medical advice? Those questions and more, this week in our conversation with author Idan Ben-Barak about his book "Why Aren't We Dead Yet?: The Survivor’s Guide to the Immune System".