Scientists have found a link between climate change and ocean currents over the past 6 million years, according to a recent study.

An expedition of scientists led by Dr. Javier Hernandez-Molina, from the Department of Earth Sciences at Royal Holloway, University of London examined core samples from the seabed off the coast of Spain and Portugal which provided proof of shifts of climate change over millions of years.

They also found new evidence of a deep-earth tectonic pulse in the region, as well as thick layers of sand within mountains of mud in a vast sheet, spreading out nearly 100km into the Atlantic from the Gibraltar gateway. Researchers said the quantity of sand is farm more than was expected.

"The sediments we examined show various shifts of climate change over millions of years," Hernandez-Molina said in a statement. "In addition, our findings could herald a significant shift in future targets for oil and gas exploration in deep-water settings. The thickness, extent and properties of these sands make them an ideal target in places where they are buried deep enough to allow for the trapping of hydrocarbons. The sand is especially clean and well sorted and therefore very porous and permeable."

The expedition, which involved an international team of 35 scientists from 14 countries, recovered 5km of core samples from an area along the Gulf of Cadiz and west of Portugal.

Based on their findings, a powerful cascade of Mediterranean water spilling into the Atlantic was scouring the rocky seafloor, carving deep-sea channels and building up mountains of mud. This is due to Mediterranean water being saltier than the Atlantic and therefore denser, causing it to plunge downwards.

"We set out to understand how the Strait of Gibraltar acted first as a barrier and then a gateway over the past six million years," Hernandez-Molina said in a statement. "The fascinating results we came back with have hugely increased our understanding of the Mediterranean Outflow Water that flows through the Gibraltar gateway and have led to some key discoveries about the relationship between climatic shifts, deep-water circulation and plate tectonic events over a huge timescale."