Climate change may actually accelerate ocean currents
Warming is making surface currents shallower and faster

Date:
April 20, 2022
Source:
University of California - San Diego
Summary:
Scientists have used computer model simulations to find that climate
change is altering the mechanics of surface ocean circulations,
making them become faster and thinner.



FULL STORY ==========================================================================
An international team led by researchers at Scripps Institution of
Oceanography at UC San Diego used computer model simulations to find that climate change is altering the mechanics of surface ocean circulations,
making them become faster and thinner.


========================================================================== These changes can have a ripple effect in the ocean, affecting
the transport of the nutrients organisms need as well as that of
microorganisms themselves.

Swifter currents may also affect the processes by which the ocean removes carbon and heat from the atmosphere and protects the planet from excessive atmospheric warming.

"We were surprised to see that surface currents speed up in more
than three- fourths of the world's oceans when we heated the ocean
surface," said study lead author Qihua Peng, who recently joined Scripps Oceanography as a postdoctoral researcher.

The study, published April 20 in the journal Science Advances, sheds
light on an underappreciated force behind the speed of global ocean
currents. It helps resolve a debate on whether currents are accelerating
as a result of global warming.

Wind has been the main factor scientists have studied to describe and
predict the speed of currents, but the research team used a global ocean
model to simulate what happens when sea surface temperatures are also increased. They found that warming makes the topmost layers of water
become lighter. The increased density difference of those warm surface
layers from the cold water beneath limits the swift ocean currents to
a thinner layer, causing the surface currents to speed up in more than three-fourths of the world's oceans. The increased speed of rotating
ocean currents known as gyres was associated with a slowdown of ocean circulation underneath. The team directly correlated the trend to the
presence of ever-increasing levels of greenhouse gases in the atmosphere.

"Our study points to a way forward for investigating ocean circulation
change and evaluatingthe uncertainty," said Scripps Oceanography climate modeler Shang-Ping Xie, whose portion of the work is funded by the
National Science Foundation.

Currents are organized into gyres in most oceans that are bounded
by continents. The Southern Ocean that rings Antarctica is an
exception. There, howling westerly winds make the Antarctic Circumpolar
Current the largest in the world in terms of volume transport. Last year, Scripps scientists detected from ocean and space observations that the Antarctic Circumpolar Current is speeding up.

"The accelerating Antarctic Circumpolar Current is exactly what our
model predicts as climate warms," said Xie.

Study co-authors include Dongxiao Wang of Sun Yat-Sen University in China, scientists from the Chinese Academy of Sciences, Woods Hole Oceanographic Institution in Massachusetts, and UC Riverside.


========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Robert
Monroe. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Qihua Peng, Shang-Ping Xie, Dongxiao Wang, Rui Xin Huang,
Gengxin Chen,
Yeqiang Shu, Jia-Rui Shi, Wei Liu. Surface warming-induced global
acceleration of upper ocean currents. Science Advances, 2022; 8
(16) DOI: 10.1126/sciadv.abj8394 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220420151356.htm

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