Human-induced changes increasing amount of natural carbon released
University Ian Carbon The The Towards Ocean Amount Westerly Periods Past Increased The Released Cardiff Natural The By And Current During International Migration Of By Circumpolar Showed Atmosphere The University/pa The Of Researchers, To How The Global Antarctic Pole Winds Warming Led Antarctic Of Team, Hall/cardiff Southern Picture:
Human-induced climate change is causing shifts in the world’s largest ocean current and westerly wind systems also seen during periods of ice age and warmer intervals in Earth’s history, researchers claim.
Their study highlighted the role of the Antarctic circumpolar current in regulating dynamics in the Antarctic Ocean and global climate patterns over the past 1.5m years.
The international team, led by Cardiff University researchers, showed how southern migration of the westerly winds and the Antarctic circumpolar current towards the pole during periods of past global warming increased the amount of natural carbon released to the atmosphere by the Antarctic Ocean.
The team warned that human-induced climate change has brought about a similar process, which is underway today and likely to continue under global warming without appropriate climate action.
Their findings offer vital insights into how heat, salt, and carbon-rich waters flow, filling a critical gap in the understanding of ocean circulation and its relationship with past and future global climate changes.
“Our study highlights the complex interplay between ocean currents and climate patterns,” said lead author Aidan Starr.
The Southern Ocean plays a central role in the global uptake of heat and carbon, with approximately 40% of annual global CO2 emissions absorbed by the world’s oceans entering through this region.
This phenomenon is largely attributed to its unique upwelling and circulation characteristics.
The team reconstructed the speed of ocean currents near the bottom of the Southern Ocean by measuring marine sediment core material retrieved on Expedition 361 of the International Ocean Drilling Program.
They uncovered systematic variations in the strength and position of the Antarctic circumpolar current during periods with extensive ice sheets known as glacial periods or ice ages, and in the warmer times without them, known as interglacial periods.
Their findings suggest that during particularly warm periods, known as super-interglacials, the mid-latitude Antarctic circumpolar current slows down, while the flow in the high-latitude Drake Passage — where the Atlantic and Pacific Oceans meet — accelerates.
“This indicates a poleward shift in the southern hemisphere’s westerly winds, which coincides with a strengthening and similar southward shift of the Antarctic circumpolar current during warmer climatic conditions," Mr Starr said.
The team says this southward shift in the Antarctic circumpolar current and westerly wind systems has massive implications for the way in which the Southern Ocean absorbs both heat and carbon.
Mr Starr added: “The urgency for comprehensive climate action has never been clearer, given the delicate balance that exists within these oceanic systems.
“By linking [Antarctic circumpolar current] flow patterns with the flow of water from the deep ocean to the surface, we gain a clearer understanding of how these dynamics have varied over millennia and what this means for our current climate trajectory.”
CLIMATE & SUSTAINABILITY HUB