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https://www.theguardian.com/environment/article/2024/jun/04/extreme-heat-oceans-acidification>
"The world’s oceans are facing a “triple threat” of extreme heating, a loss of
oxygen and acidification, with extreme conditions becoming far more intense in
recent decades and placing enormous stress upon the planet’s panoply of marine
life, new research has found.
About a fifth of the world’s ocean surface is particularly vulnerable to the
three threats hitting at once, spurred by human activity such as the burning of
fossil fuels and deforestation, the study found. In the top 300 meters of
affected ocean, these compound events now last three times longer and are six
times more intense than they were in the early 1960s, the research states.
The study’s lead author warned that the world’s oceans were already being
pushed into an extreme new state because of the climate crisis. “The impacts of
this have already been seen and felt,” said Joel Wong, a researcher at ETH
Zurich, who cited the well-known example of the heat “blob” that has caused the
die-off of marine life in the Pacific Ocean. “Intense extreme events like these
are likely to happen again in the future and will disrupt marine ecosystems and
fisheries around the world,” he added.
The research, published in
AGU Advances, analyzed occurrences of extreme
heat, deoxygenation and acidification and found that such extreme events can
last for as long as 30 days, with the tropics and the north Pacific
particularly affected by the compounding threats.
Climate scientists have been alarmed by the relentless onward rise of heat in
the ocean, which has hit extraordinary heights in recent months. “The heat has
been literally off the charts, it’s been astonishing to see,” said Andrea
Dutton, a geologist and climate scientist at the University of
Wisconsin–Madison, who was not involved in the new research. “We can’t fully
explain the temperatures we are seeing in the Atlantic, for example, which is
part of the reason why hurricane season is such a concern this year. It’s quite
frightening.”
But on top of the heat, which forces fish and other species to move, if they
are able, to more suitable climes, the oceans are also paying another heavy
price for soaking up huge volumes of heat and carbon dioxide from fossil fuel
emissions that would otherwise further warm the atmosphere for people on land.
The extra CO2 is making seawater more acidic, dissolving the shells of marine
creatures, as well as starving the ocean of oxygen.
“This means that marine life is being squeezed out of places it is able to
survive,” said Dutton. “This paper makes clear that this is happening now and
that these compound threats will push organisms past their tipping points.
People have to recognize that oceans have been buffering us from the amount of
heat we have been feeling on land as humans, but that this hasn’t been without
consequence.”
Dutton said that the combination of dropping oxygen levels, rising
acidification and soaring ocean heat was also seen at the end of the Permian
period about 252m years ago, when Earth experienced the largest known
extinction event in its history, known as the Great Dying."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
