A tectonic upheaval may have caused a significant global warming episode during the Early Cretaceous, according to a team of geoscientists who have pushed back the opening date of the Equatorial Atlantic Gateway to 117 million years ago, four million years earlier than previously believed.
The discovery is based on recently examined sediment cores and seismic data that were collected more than 3,000 feet below the Atlantic seafloor, some 250 miles west of Guinea-Bissau.
How did scientists make the discovery?
When dense, salty water first flowed northward from isolated basins south of the gateway, researchers discovered enormous “waves” of mud that were up to a kilometre long and several hundred metres high.
These waves were created by strong bottom currents.
These basins served as enormous carbon traps, trapping greenhouse gases in dense sedimentary layers that were rich in organic matter until the seaway opened.
Heavy saltwater poured downslope once the undersea barrier broke, eroding the seabed and upsetting carbon burial.
According to marine isotope data, the ensuing decrease in carbon sequestration occurred between 117 and 110 million years ago, when there was a noticeable increase in global temperature.
“The sediment waves show that the opening started earlier, from around 117 million years ago,” Dr Debora Duarte, a researcher at Heriot-Watt University, told Earth.com.
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Early changes to the climate
According to Duarte, changing ocean circulation altered the carbon cycle, warming the planet well before other major drivers came into play.
Implications of the work go beyond paleoclimate history.
Similar density-driven fluxes are essential to contemporary ocean systems, such as the Atlantic Meridional Overturning Circulation.
Scientists caution that temperature and salt fluctuations, like those caused by ice sheet melt, may result in similar circulation alterations that have long-term effects on the climate.
The finding highlights how even small ocean passageways may alter planetary systems and offers a precise benchmark for climate models by detecting the earliest evidence of deep-water flow between Africa and South America.
In order to explore the entire area of these ancient currents and improve reconstructions of Cretaceous climate dynamics, the study, which was published in Global and Planetary Change, now encourages additional coring activities in Brazil and Angola.
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Shameeka Voyiya 
Newsjustnews writers 
Ren Azrack Escosio