The Southern Ocean could become seven times hotter this century

Our oceans have absorbed over 90 percent of carbon monoxide emissions in the last 50 years, and the Southern Ocean has taken on the most of these emissions. 

“The Southern Ocean dominates this ocean heat uptake, due in part to the geographic set-up of the region,” said study lead author Maurice Huguenin, a PhD candidate at the University of New South Wales. “Antarctica, which is surrounded by the Southern Ocean, is also surrounded by strong westerly winds.”

“These winds influence how the waters absorb heat, and around Antarctica they can exert this influence while remaining uninterrupted by land masses – this is key to the Southern Ocean being responsible for pretty much all of the net global ocean heat uptake.”

Huguenin explained that cold water is drawn to the ocean’s surface due to the uninterrupted wind patterns near Antarctica. As water is driven to the north, it absorbs heat from the atmosphere. Unfortunately, the South Ocean won’t save us from the effect of climate change and rising sea levels.

“Sea levels are rising because heat causes water to expand and ice to melt. Ecosystems are experiencing unprecedented heat stress, and the frequency and intensity of extreme weather events is changing,” said study co-author Matthew England. “All future projections, including even the most optimistic scenarios, predict warmer oceans in the future.”

“If the Southern Ocean continues to account for the vast majority of heat uptake until 2100, we might see its warmth increase by up to seven times more than what we have already seen up to today.”

This increase in warmth would be felt worldwide. It would affect the Southern Ocean’s food web, causing ice shelves to melt, and impact ocean currents.

The scientists hope this research encourages ongoing monitoring of the Southern Ocean, including using Argo floats, instruments that can track the ocean’s temperature, even at great depths. There is also an urgent need to reduce carbon emissions.

“The less carbon dioxide we emit into the atmosphere, the less ocean change and sea-level rise we will lock in,” said the researchers. “This can help limit the level of adaptation required by the billions of people living near the ocean, by minimising the detrimental impacts of ocean warming on both sea-level and their primary food source.”

This research is published in Nature Communications.

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By Erin Moody , Earth.com Staff Writer