Beijing, May 5 (Reporter Sun Zifa) The Institute of Tibetan Plateau Research of the Chinese Academy of Sciences (Institute of Tibetan Plateau of the Chinese Academy of Sciences) released news to the media on the 11th, saying that the latest cooperative study by Chinese and foreign scholars found that with the periodic decline of sea level during the glacial cycle, the salinity of the sea surface of the Indian Ocean has risen regularly, and after reaching its peak during the peak ice period, it has rapidly declined with the outbreak of the ice extinction. This suggests that the import of salt water from the Indian Ocean into the Atlantic Ocean for 11.120 million years contributed significantly to the end of the ice age.
The study of seawater temperature salinity changes during the glacial period, carried out by scholars from Cardiff University and the University of St Andrews, Taiwan University, and the Tibetan Plateau Institute of the Chinese Academy of Sciences, used a deep-sea sediment core about 40 meters long in the northern Mozambique Channel to reconstruct changes in seawater temperature and salinity over the past 120.5 million years by measuring chemical fingerprints and numerical simulations stored in tiny fossil shells. His research paper was published online in the internationally renowned academic journal Nature on the evening of May 10, Beijing time.
Sophie Nuber, the first author and corresponding author of the paper, a postdoctoral fellow at Taiwan University, said that the subtropical sun is abundant, and the evaporation of seawater will cause the sea water to become salty. Typically, Indian Ocean waters are diluted by fresh water from the Pacific Ocean due to the presence of Indonesian through-currents; But falling global sea levels have weakened freshwater inputs, leading to the accumulation of salt in the Indian Ocean.
During the glacial period, the continental ice sheet caused global sea level to drop by hoarding fresh water evaporated from the ocean, which caused global sea level to drop (up to 120 meters during the peak ice period), and the Indonesian archipelago gradually turned land, cutting off the passage of fresh water from the Pacific Ocean into the Indian Ocean (i.e., the Indonesian through-stream).
Zhang Xu, a researcher at the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences and the main author of the paper, explained that during the glacial development stage, the Indian Ocean gradually became a saltwater reservoir, storing high salt water that was not diluted by fresh water. During the glacial extinction, the Agulhas Current in southern South Africa gradually recovers, like opening the floodgates of saltwater reservoirs, allowing high salt water to quickly pour into the Atlantic Ocean, promoting the recovery of the Atlantic circulation system.
"More than a decade ago, we found that the Atlantic circulation system experienced a significant weakening during the glacial extinction," says Professor Stephen Barker of Cardiff University and one of the paper's authors, adding that the latest findings suggest that the impetus (brackish water) that led to the recovery of the circulation came from the Indian Ocean tens of thousands of kilometres away.
Lead author Dr James Rae of the University of St Andrews said the study further confirmed that parts of the climate system are closely interconnected and affect the whole body, and that changes in ocean circulation and seawater properties in a given region caused by global warming can have a huge impact on the climate on the other side of the world. "So we need to stop global warming and prevent the balance of these critical circulation systems from being upset."
The collaborative team concluded that at present, the current that transports high-temperature and high-salt water to the North Atlantic is still active, but as the global temperature continues to rise, the polar ice caps melt, and the sea water of the North Atlantic and Southern Oceans is constantly diluted, which may lead to the weakening of this current and trigger a series of climate chain reactions. (End)