Melting Antarctic ice causing dramatic ocean current slowdown, heading for collapse – study
- New study published warns rapidly melting Antarctic ice is causing slowdown in deep ocean currents
- Deep-water flows that drive ocean currents could decline by 40% by 2050
- Slowdown in North Atlantic current could cause Europe to become colder
- Slowdown will reduce ocean’s ability to absorb carbon dioxide from atmosphere
- Deep currents have been stable for thousands of years but now disrupted by warming climate
The ice caps in Antarctica are melting at an alarming rate, and if we don’t take action, we could face disastrous consequences.
A new report from Australian scientists warns that the rapid melting of the Antarctic ice is causing a dramatic slowdown in deep ocean currents. These currents are responsible for carrying vital heat, oxygen, carbon, and nutrients around the globe.
If we don’t act fast, the deep-water flows that drive these ocean currents could decline by a massive 40% by 2050.
Previous research suggests that a slowdown in the North Atlantic current could cause Europe to become colder. But that’s not all; this study, published in the prestigious journal Nature, also warns that the slowdown could reduce the ocean’s ability to absorb carbon dioxide from the atmosphere.
The report outlines how the Earth’s network of ocean currents is partly driven by the downwards movement of cold, dense saltwater towards the sea bed near Antarctica. But as fresh water from the melting ice caps mixes with the sea water, it becomes less salty and dense, causing the downwards movement to slow.
These deep ocean currents, or “overturnings,” in the northern and southern hemispheres have been relatively stable for thousands of years, but they are now being disrupted by the warming climate. “Our modelling shows that if global carbon emissions continue at the current rate, then the Antarctic overturning will slow by more than 40 per cent in the next 30 years – and on a trajectory that looks headed towards collapse,” study lead Professor Matthew England said.
More meltwater into ocean
Dr Adele Morrison, who contributed to the report, explained that as ocean circulation slows down, water on the surface quickly reaches its carbon-absorbing capacity and is not replaced by non carbon-saturated water from greater depths. This means that the ocean’s ability to absorb carbon dioxide from the atmosphere is severely compromised.
The 2018 Atlas Study found that the Atlantic Ocean circulation system was weaker than it had been for over 1,000 years and had changed significantly in the past 150. It suggested changes to the conveyor-belt-like Atlantic Meridional Overturning Circulation (Amoc) could cool the ocean and north-west Europe, and affect deep-sea ecosystems.
But a slowdown of the southern overturning would have more of an impact on marine ecosystems and Antarctica itself. “Overturning brings up nutrients that have sunk down to the bottom when organisms die… to resupply nutrients for the global ecosystem and fisheries,” she told the BBC.
Furthermore, a slowdown in the southern overturning could open a pathway for warmer waters, which could cause increased melting, leading to a further feedback, putting more meltwater into the ocean and slowing down circulation even more.
Scientists spent a mind-blowing 35 million computing hours over two years to produce their models, which suggest deep water circulation in the Antarctic could slow at twice the rate of decline in the North Atlantic. “[It’s] stunning to see that happen so quickly,” said climatologist Alan Mix from Oregon State University, a co-author of the latest Intergovernmental Panel on Climate Change (IPCC) assessment. “It appears to be kicking into gear right now. That’s headline news,” he told Reuters.
And on top of that, the effect of Antarctic meltwater on ocean currents has not yet been factored into IPCC models on climate change, but Prof England said it is going to be “considerable.”
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