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Finely balanced nutrient, oxygen and carbon circulation is being ‘handbraked’ in Southern Ocean.
Century-long impacts to marine ecosystems and global climate beckon if Antarctic deep ocean circulation collapses, say Australian scientists.
Evoking ‘The Day After Tomorrow’, a film where the shutdown of North Atlantic ocean currents shut down and cause widespread and rapid climate change, this new research explores the real-world slowing of similar processes in the Southern Ocean around Antarctica.
The research examines overturning circulation: a natural process by which a web of deep-water ocean currents act like a conveyer belt, transporting nutrients, oxygen, carbon and heat from the depths of the sea around the globe, shaping climate systems and marine life. It is a finely balanced system.
But new modelling, led by Professor Matthew England from UNSW, says this process could slow by more than 40% and collapse by the midpoint of the century, assuming the current global rate of greenhouse gas emissions continues.
This, more than other atmospheric influences, is pulling the handbrake on overturning circulation.
Meltwater diluting density
In Antarctica, hundreds of trillions of tonnes of dense salt water sinks to the bottom of the ocean every year.
This water is rich nutrients, thanks to the deterioration of dead animal matter sinking with it. Deep ocean currents convey this material northward to the Atlantic, Pacific and Indian oceans.
But the process is being altered by meltwater – the term given to freshwater released by thawing ice in Antarctica. Meltwater is increasing, driven by ever-increasing greenhouse gases pushing global temperatures higher.
How worried should we be about melting glaciers in Antarctica?
The freshwater effectively dilutes the density of deep ocean salt water. With less water sinking to the ocean’s depths, the overturning circulation process will slow, in turn preventing the movement of nutrients, oxygen and heat to other regions.
In addition, England says this process has “knock on” effects that will see the ability of the ocean to absorb carbon reduced, and lead to changes in tropical rainfall bands and the health of marine ecosystem productivity.
These also affect North Atlantic overturning – the central idea to the ‘Day After Tomorrow’ – which is already estimated by scientists to be at a thousand-year minimum.
“Once you change the overturning circulation, you reset the global energy balance,” England says.
“And you can shift the ITCZ – the intertropical convergence zone, the big rainfall bands in the tropics – almost synchronously with those changes.
“It’s almost an instantaneous response in the atmosphere.”
A landmark study, and a call to action for carbon cuts
With the rate of ice melt driven by greenhouse gas rises, the research published by England’s team adds an important, antipodean perspective to add to existing research on North Atlantic overturning slowdown.
Oceanographer Professor Trevor McDougall, also based at UNSW but not involved with the research, described the modelling as a “landmark study”.
“This study is the first to shed light on the causes of the warming at the bottom of the Southern Ocean, and importantly, the mechanisms that are causing this warming,” McDougall says.
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In highlighting the influence of Antarctic waters on global nutrient and energy flows, it marks what the authors describe as another “piece of the puzzle” towards understanding the interconnected impacts of climate change.
Their modelling was performed under the ‘high’ IPCC climate change scenario, which puts the Earth on a three-degree warming pathway if there is little change to current global carbon emissions.
The Science Briefing: The observatory buried under Antarctic ice
Aside from the impacts of slowed overturning processes on climate conditions, the consequences for marine productivity are also severe – directly impacting food chain foundations by diminishing phytoplankton availability and cutting feeding opportunities for larger fish and marine mammals.
“The choices we make today … commit us to a certain level of warming. That certain level of warming goes along with a certain amount of ice melt, so we commit ourselves now to this freshwater input,” says Dr Steve Rintoul, who leads the CSIRO’s Southern Ocean research team.
“What our study does is show what the impacts of that freshwater input are.”
Earlier in March, the IPCC synthesis report forecast current, high levels of carbon emissions would lead to major pressure on ecosystems, fish stock depletion and three to four times the number of extreme climate events within the lifetimes of children born today, compared to Baby Boomers.
This article was originally published on Cosmos Magazine and was written by Matthew Ward Agius. Matthew Agius is a science writer for Cosmos Magazine.
They also predicted that there would be no glaciers left by 2020 and some of the glacier parks forgot to quietly remove the signs saying this before 2020 rolled around. Even using the faulty models and ‘adjusted’ data, the ‘high IPCC climate change scenario’ is admitted to be basically impossible by the IPCC its self, even though that’s the one the climate disasterist quote all the time.
Christian the whistle Blowers that have left the
IPCC tell a very different story to those still
In this “travelling cocktail party ” organisation..
No Emergency at all.. just a mouth piece
for the elites who have invested Trillions
Into Renewable energies.. !!
“travelling cocktail party” – Exactly.
Sacred cows don’t die, they fade away. Once they have cashed in, the left will say this all never happened, or they didn’t make THAT big of a deal about it. Your memory is just wrong. Besides, we should be concentrating on the new ‘latest thing’ they will make up. And they will quietly change the temp data back.
Of course !!
Whatever chance we had of halting anthrpocentric climate change (assuming it is a valid thing) went out the political window due to the following events
1. The failure of the West to pay carbon credit to Amazonian countries and South-East Asian cojntries to protect rainforest.
2. Placing the burden of reducing green house gases on Western farmers instead of on oil companies.
3. Transposing the ‘trust in the science” mantra from climate to covid vaccines, thereby inducing a deep mistrust in science across two thirds of the globe.
Directions taken, consequences awaited.
And when nothing happens, what are you going to do about it?
Who predicted “that there would be no glaciers left by 2020”?
A quick search of reliable sites on the internet will show that the majority of glaciers are retreating, with some smaller ones disappearing altogether. My memories and family photos confirm this for major NZ glaciers.
While the glaciers in the Glacier National Park did not disappear by 2020, as a few signs in the park stated, the glaciers within the park shrank significantly. The signs with the 2020 date have been updated in light of new knowledge and continued research. See https://yaleclimateconnections.org/2019/09/fact-check-no-the-glaciers-are-not-growing-in-glacier-national-park/
The climate is constantly changing and will continue to do so.
There is greater effect on world climate due to axis-change and volcanic eruptions etc.
Looking back over recorded history there have been many violent climate changes due to completely natural events.
The Romano-British were growing wine in southern England, now production has started again, 2,000 year later.
The French Revolution in 1780s was partially caused by another one – as was the ‘Little Ice Age” in the 18th century.
Thus, using current glacier events in NZ to make panicked political points may be unwise historically.
Wow trust an article like this to bring out comments about human caused climate being debatable. Next week an article on the earth being round will bring comments about it being debatable and the earth is really flat. It just goes on and on reading irrational arguments trying to sound rational.
Then it should be real easy to make counter-arguments to ‘irrational arguments’. Try. I just got censored for repeating info from Cosmos articles so you’re getting plenty of help.
Understanding and accepting the science, it all too hard.
Joachim have you or your Gaslighting Alarmist looked up the meaning of the
Word “Emergency” ? “Imminent danger ”
Like now this very minute Joachim.
Have you been in such danger in the past
Month that your life is in danger
From this apparent climate change Emergency Joachim ? Do you think
This Climate change Nonsense is more dangerous than driving a car everyday?
The Floods ‘ and fires ..”we live in a
Land of drought’s and flooding rain’s ”
What goes around comes around..!