The study, led by the University of Bristol in the UK and Nanjing University in China, examined historic deep-sea corals to shed intriguing new light on the history of ocean chemistry.
Understanding what has led to the pre-industrial rise in carbon dioxide (CO2) levels during the Holocene period, which dates back some 11,700 years to the present day, is a source of scientific debate. One theory suggests the increase in physical upwelling of carbon-rich deep waters to the surface of the Southern Ocean, in other words changes in high-latitude ocean circulation, may have triggered the release of marine carbon into the atmosphere, although this is not fully understood.
Lead author Tianyu Chen, Professor of Marine Geochemistry at Nanjing University and the University of Bristol, said: "Our research challenges assumptions about the role of ocean circulation in the carbon cycle during the Holocene. By providing radiocarbon evidence for the stability of these processes, we pave the way for a deeper understanding of the complex interactions between the ocean and the Earth's climate system."
The Holocene, which followed the retreat of major ice sheets in the Northern Hemisphere, is the Earth’s most recent interglacial period and has long intrigued scientists studying Earth's recent climate history. A key aspect of this period is the rise in atmospheric CO2 levels. Initially, in the early Holocene, CO2 levels were approximately 260 parts per million by volume (ppmv). However, over the course of around 5,000 years they increased by 20 ppmv, equivalent to around 150 gigatons of CO2.
Read more at University of Bristol
Image: Deep-sea coral garden located in the Drake Passage seamount; image captured by a remotely operated vehicle (ROV). Credit: Laura F. Robinson