Washington: A team of researchers has pinpointed the abrupt onset of modern day Indian Ocean Monsoon system, offering some clues to future climate changes and sea-level rise.
Their study revealed the exact timing of the onset of the modern monsoon pattern in the Maldives 12.9 million years ago, and its connection to past climate changes and coral reefs in the region. The analysis of sediment cores provides direct physical evidence of the environmental conditions that sparked the monsoon conditions that exist today around the low-lying island nation and the Indian subcontinent.
In November 2015, University of Miami (UM) geoscientist Gregor Eberli, along with his co-chief scientist Christian Betzler and an international team of 31 scientists from 15 countries, embarked on an eight-week expedition to the Maldives aboard the research vessel JOIDES Resolution. The scientific team on International Ocean Discovery Program (IODP) Expedition 359, which included UM geochemist Peter Swart and sedimentologist Anna Ling, extracted 3,097 meters of sediment cores that contain the history of the monsoon that is the most intense annually recurring climatic element on Earth.
The monsoon system supplies moisture to the Indian subcontinent, which is important for the human population and vegetation in the region, as well as marine ecosystem in the surrounding seas.
The Maldives are a string of island atolls built on coral reefs located in the middle of the Indian Ocean. The waters around the low-lying archipelago has steadily risen and fallen for millions of years in sync with the changing climate. A new climatic phase heightened by human influence has these waters rising again, endangering the existence of the popular island paradise.
“They are at the center of the storm for sea-level rise,” said senior author Eberli.
The low-lying island nation offers the scientists a unique opportunity to reconstruct climate conditions during previous periods of varying sea levels to help scientists better understand how future climate change will the effect the 1,000 km-long archipelago and low-lying coastal areas all around the world.
Most scientists agree that the South Asian Monsoon is linked to the initial uplift, or birth of the Himalayas, but the timing and other environmental drivers at play are still in question. During Expedition 359, Eberli’s team drilled seven holes along the Maldives Archipelago to collect sediments that hold records of past sea level and environmental changes during the Neogene, a geological time period that began 23 million years ago. The information can help pinpoint the timing and environmental conditions that supported the development of the modern day ocean currents and monsoon conditions.
“We have unraveled the physical evidence of the monsoon and now know the exact timing of when the modern monsoon pattern began, and have shown what consequences the onset of the monsoon had on the coral reefs of the Maldives,” said Beztler. “The scientific results of this expedition will give answers to many fundamental questions of the monsoon and the climate in general.”
Eberli suggested that the abrupt development of the modern-day monsoon conditions were not only due to the uplift of the Himalayas, which is a pre-requisite, but ultimately the result of the cooling after the Miocene Climate Optimum, which initiated the formation of the bipolar ocean circulation that is still in existence today.
The study is published in the journal Scientific Reports. (ANI)