The study, involving institutions from Asia, Europe and Australia, was published in Nature Communications. It demonstrates the role of changes in ocean circulation and heat stored beneath the sea surface
Researcher Gianluca Marino from the Centro de Investigación Mariña (CIM) at the University of Vigo has participated in an international study published in the scientific journal Nature Communications, demonstrating the role of changes in ocean circulation and heat stored beneath the sea surface in the accelerated melting of large ice sheets at the end of ice ages.
Marino, who heads the Paleoclimatology Lab at the centre, contributed his expertise in the study of past climatic and oceanic changes using geochemical and micropaleontological tools and advanced statistical models. “Understanding how the climate system responded in the past is essential for anticipating the future impacts of climate change,” says Marino, who also highlights that “ocean heat storage is one of the most important features of current global warming, as the oceans absorb around 90% of the excess heat generated by human greenhouse gas emissions.”
The dual role of accumulated heat
The new study, Protracted ocean circulation slowdown drove exceptional ice-sheet melting during ice age termination IV, identifies a dual role for this accumulated heat. On one hand, when Atlantic Ocean circulation weakens, heat builds up beneath the sea surface and interacts with the base of the massive ice sheets present during glacial periods. On the other, when circulation resumes, some of that heat is rapidly released into the atmosphere at high latitudes, further accelerating ice melt.
The research sheds new light on the rapid disintegration of ice sheets during the last five transitions between ice ages and warm periods, including an exceptional episode that occurred around 340,000 years ago, when sea levels rose by up to five metres per century. “By constructing an extremely precise chronology of past climate events, we discovered a close relationship between the duration of Atlantic circulation weakening and the rate of ice sheet melting,” Marino explained.
“Climate model simulations revealed that the main driver of this process was the accumulation of heat in the ocean during periods of reduced circulation, helping to explain one of the fundamental mechanisms of glacial-interglacial transitions,” he added.
Innovative analytical technique
The study brings together leading scientific institutions from Asia, Europe and Australia and was led by Hsun-Ming Hu of the Chinese Academy of Sciences, with Gianluca Marino of the CIM as second author and principal contributor, and River Shen of National Taiwan University, Hu’s former doctoral supervisor.
The team developed an innovative analytical technique capable of dating palaeoclimate records with unprecedented precision going back 600,000 years. This methodology was applied to cave carbonates — known as speleothems — from northwest Italy, revealing that Atlantic circulation remained weakened for around 12,000 years during the episode that occurred approximately 340,000 years ago.
During that period, around 15 × 10²⁴ joules of energy accumulated in the deep ocean. The joule is the unit used in physics to measure energy and heat, and this figure represents an enormous quantity of heat stored beneath the ocean surface. Once released towards the surface and atmosphere, this heat contributed to the rapid melting of the large continental ice sheets.
The CIM holds the CIGUS recognition from the Xunta de Galicia, which accredits the quality and impact of its research, and its activity is co-funded by the European Union through the ERDF Programme 2021–27.
Source: DUVI
