Among the very strange and spooky impacts of climate change:
changes in the behavior of massive oceanic current patterns.
(Image: The Indonesian Straits, which provide a conduit between
the Pacific and Indian Oceans. They are described as the only place on the
planet where oceans interact the way they do here, and the only place in the tropics where oceans are able to interact. Source: University of Hawai`i.)
New research suggests that climate change will alter the
flow between the Pacific and Indian Oceans through the Indonesian straits. That’s
on top of changes in the flow that are driven
by the alternating El Nino-La Nina climate cycles.
What this will mean longer-term is not yet entirely clear,
but there are suggestions that the changing flow could change the climate in
both oceans. A better understanding of the changes could result in better
forecasts of climate activity, according to a new paper.
The flow of ocean water through the Indonesian strait
appears to have become both shallower and stronger, according to a study
published June 22 in the journal Nature Geoscience. The paper is entitled “The
Indonesian seas and their role in the coupled ocean-climate system.”
UH Mānoa physical oceanographer James Potemra is a
co-author. The lead author is Janet Sprintall of Scripps Institution of
Oceanography at UC San Diego, and other co-authors are Arnold Gordon of
Lamont-Doherty Earth Observatory at Columbia Unversity, Ariane Koch-Larrouy of
LEGOS in France, Tong Lee of the Jet Propulsion Laboratory in Pasadena, Calif.,
Kandaga Pujiana of Oregon State University and Insitut Teknologi Bandung in
Indonesia, and Susan Wijffels of the Commonwealth Scientific and Research
Organization in Australia.
Eric Lindstrom, co-chair of NASA’s Global Ocean Observing System Steering
Committee, which funded part of the study, talked about its importance:
“This is a seminal paper on a key oceanographic feature that
may have great utility in climate research in this century. The connection of
the Pacific and Indian oceans through the Indonesian Seas is modulated by a
complex circulation, climate variations, and sensitive ocean-atmosphere
feedbacks. It’s a great place for us to
sustain ocean observations to monitor potential changes in the ocean’s general
circulation under a changing climate.”
Lead author Sprintall said: “Now that we have a better
understanding of how the Indonesian Throughflow responds to El Niño and La Niña
variability, we can begin to understand how this current behaves in response to
changes in the trade wind system that are brought on through anthropogenic
climate change. Changes in the amount of
warm water that is carried by the throughflow will have a subsequent impact on
the sea surface temperature and so shift the patterns of rainfall in the whole
Asian region.”
Here’s some complex language from the paper on what’s going
on with the currents: “A synthesis of observational data and model simulations
indicates that the temperature, salinity and velocity depth profiles of the
Indonesian throughflow are determined by intense vertical mixing within the
Indonesian seas. This mixing results in the net upwelling of thermocline water
in the Indonesian seas, which in turn lowers sea surface temperatures in this
region by about 0.5 °C, with implications for precipitation and air–sea heat
flux.”
A University of Hawaii press release discusses the paper.
More information on this kind of stuff at the website of the International PacificResearch Center at University of Hawai`i at Mānoa.
© Jan TenBruggencate 2014
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