The study, 'Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater', is the first to look at how the melting of ice around Antarctica plays into world ocean circulation.
Dr Victoria Metcalf is a New Zealand Scientist specialising in marine biology, climate change and Antarctica.
She described Antarctica as the on/off switch for the sea.
“The motor for world ocean circulation is Antarctica, particularly the Antarctic bottom water. It drops down into the ocean's cold depths, feeds nutrients into all the other oceans, and powers them along.”
She said not only was the increase of ice melting freshening the water, but it also slowed down the flow of the bottom water and heats it up.
Although not involved in the study, Metcalf said the findings were significant and alarming but not surprising, as it had been hypothesised for a long time.
Key researcher Professor Matthew England (Deputy Director of the ARC Centre for Excellence in Antarctic Science in Sydney) said the flow of ocean currents below 4000 metres would become stuck, reducing the supply of nutrients to marine life that lives higher up. The process of ocean circulation is also known as overturning.
“Such profound changes to the ocean’s overturning of heat, freshwater, oxygen, carbon and nutrients will have a significant adverse impact on the oceans for centuries to come.”
It is unclear how or to what extent different marine life will be affected by the slowing of this process.
Metcalf said the balance in our ecosystems would shift. Some plankton and animals would do better than others, but it was unknown how the balance would shift at this point.
Metcalf said it was hard for biologists to study this. Usually when a study was done it would focus on one or two factors because this was easier to track. But, with our ocean circulation or overturning, there were many, many stressors at play.
“I think our understanding of the impacts will be far slower than these types of papers.”
England said it was hard to turn the ship around on these sorts of physics, but there was no doubt emission reductions would lower our meltwater impact.
Metcalf emphasised that although it seemed all doom and gloom, it was important to never give up hope. There were small steps that we can all take to make a difference, like using public transport, electric vehicles and cutting down power usage.
“Even simple things like reducing food waste are not putting as much carbon into the atmosphere. People want change and a commitment in this space, so we can have a more stable world for decades to come.”
Recent data from StatsNZ shows Kiwis may already be doing their part to turn the ship around. New Zealand’s greenhouse gas emissions fell 3.5 percent in the last quarter of 2022, the lowest it has been in eight years.
For the full study go to: https://www.nature.com/articles/s41586-023-05762-w
For StatsNZ data go to: https://www.stats.govt.nz/news/total-greenhouse-gas-emissions-fall-3-5-percent-in-the-september-2022-quarter/?fbclid=IwAR2nQV6J89lMjRtc_q36gcdrD64OvkRC22LaVuVc0RAuk9Pa3c_Qxp6bnz0