The world’s climate might change by 40% in just three decades, according to new research by Australian experts.
According to experts behind this research, melting ice around Antarctica will trigger a rapid slowdown of a significant global deep ocean current by 2050, which could change the climate of the entire planet for centuries and hasten sea level rise.
According to the findings, if greenhouse gas emissions keep rising at the current rate, the deep ocean circulation could slow down by 40% in just three decades.
The experts warned that this might have a domino effect, raising sea levels, changing weather patterns, and depriving marine life of an essential supply of nutrients.
A group of Australian researchers studied the deep ocean current that flows across ocean basins all around the world and begins in cold, fresh, and dense waters that tumble down off Antarctica’s continental shelf.
The entire deep ocean current is on the verge of collapsing, according to Prof. Matt England of the Climate Change Research Centre at the University of New South Wales and co-author of the study published in Nature.
“In the past, it took these circulations more than a thousand years or so to change, but now it takes only a few decades. We underestimated how quickly these circulations could slack off.
We’re discussing the potential long-term extinction of a famous water mass.
The study investigated the effects of including fresher water melting from ice sheets in climate modeling on what might occur in the deep ocean surrounding Antarctica.
According to England, lower emissions could reduce the amount of ice melting, which in turn could slow the decline. The modeling for the study made the assumption that global greenhouse gas emissions would continue on their current course.
The amount of water that sinks to the bottom and then flows north is related to the slowing of the deep ocean current.
The research, which was overseen by England, was written by Dr. Qian Li, a former employee of the University of New South Wales who is now at the Massachusetts Institute of Technology.
Although the authors of the study did not attempt to explain or quantify the ripple effects, they noted that the slowing would “profoundly affect the ocean overturning of heat, fresh water, oxygen, carbon, and nutrients, with ramifications felt throughout the global ocean for centuries to come.”
The authors claimed in a briefing that the deep ocean circulation had the power to significantly alter rainfall and had an impact on climate all throughout the planet.
According to England, the deep ocean current’s slowing led the deep waters to warm up.
Yet when that deep water isolates, it might lead to a warming of the top ocean surrounding the continent, starting a feedback cycle whereby more melting results in a sped-up slowdown of the current, which then leads to greater heating and ice sheet melt.
According to England, the study’s deep water warms up most quickly in regions where ice sheets are already unstable and melting, particularly in west Antarctica.
He added that the slowness effectively causes the deep ocean to stagnate, depleting it of oxygen, warning that “we don’t want to set off a self-reinforcing mechanism in those locations.”
When marine life perishes, nutrients are added to the water that settles to the bottom and circulates throughout the oceans of the planet. In upwells, the nutrients are recycled and fed to phytoplankton, the base of the marine food web.
Oceanographer and Southern Ocean specialist Dr. Steve Rintoul of the Commonwealth Scientific and Industrial Research Organisation of the Australian government said that as deep ocean circulation slows, fewer nutrients will be returned to the ocean’s upper layers, which will have an impact on phytoplankton production. This process would take several centuries to complete.
“Once that overturning circulation slows down, the only way to restart it is to stop discharging meltwater around Antarctica, which necessitates a cooler temperature while we wait for it to restart,” he explained.
“The more reforms we commit to, the longer we continue with increasing rates of greenhouse gas emissions.”
The modeling, according to the scientists, was consistent with recent observations of changes in the deep ocean circulation, which indicated that a slowdown may already be occurring.
Looking back 20 years, Rintoul continued, “We assumed the deep ocean wasn’t changing that much. Too far away for it to respond. Observations and mathematical models, however, have demonstrated that this is false.
The Atlantic Meridional Overturning Circulation, a significant ocean circulation in shallower waters that covers the whole Atlantic Ocean, is likewise believed by scientists to be slowing down.
The current study, in which he was not engaged, revealed “a dramatic additional weakening is predicted around Antarctica in the next decades,” according to Prof. Stefan Rahmstorf, an oceanographer and head of earth system analysis at the Potsdam Institute for Climate Impact Research.
He claimed that because models used in significant UN climate reports failed to account for how meltwater affects the deep ocean, they had a “longstanding and significant weakness.”
Only a few locations on the planet, near the largest ice sheets in Greenland and Antarctica, had their ocean depths refilled.
“Unfortunately, all of these places are near the melting Greenland and Antarctic ice sheets, which are the result of global warming brought on by fossil fuels.
The ocean waters in these locations become less thick as a result of the meltwater’s dilution of the salt content, which prevents them from being heavy enough to sink and drive the existing waters away.
The amount of CO2 that the deep seas could absorb if the deep ocean current slowed down