Mineral vegetation reveals unprecedented modern sea level rise

Hidden in caves: mineral vegetation reveals unprecedented modern sea level rise

Professional divers assisted researchers in searching for mineral vegetation in cave systems in Mallorca, Spain. Credit: University of South Florida

The early 1900s were an exciting time around the world, with rapid advances in the steel, electrical and automotive industries. The industrial changes also mark a turning point in our climate. According to an international team of researchers led by the University of South Florida (USF), sea levels have risen 18 centimeters since the early 1900s.

The study, featured on the cover of the July 1 issue of scientific progressworks to identify pre-industrial sea levels and examine the impact of modern global warming on sea ​​level to get up.

The team, which includes USF graduate students, traveled to Mallorca, Spain – home to more than 1,000 cave systems, some of which have deposits formed millions of years ago. For this study, they focused on analyzing deposits from 4,000 years ago to the present.

The team found evidence of a previously unknown 20 centimeters sea ​​level rise that happened nearly 3,200 years ago when ice sheets melted naturally over the course of 400 years at a rate of 0.5 millimeters per year. Furthermore, the sea level remained exceptionally stable until 1900, despite major climatic events such as the Medieval Warm Period and the Little Ice Age.

“The results reported in our study are alarming,” said lead author Bogdan P. Onac, a geology professor at USF. “Sea level rise since the 1900s is unprecedented compared to the natural change in ice volumes over the past 4,000 years. This means that if global temperatures continue to rise, sea levels could eventually reach higher levels than scientists had previously estimated.”

Hidden in caves: mineral vegetation reveals unprecedented modern sea level rise

Mineral vegetation of the Vallgornera cave in Spain. Credit: University of South Florida

To create the timeline, the team collected 13 samples from eight caves along the Mediterranean coastline. The deposits are rare — they only form near the shoreline in cave passages that have been repeatedly inundated by seawater, making them accurate markers of sea level changes over time. Each deposit provides valuable insight into both the past and the future, helping researchers determine how quickly sea levels will rise in the coming decades and centuries.

The samples were taken to the University of New Mexico and the University of Bern in Switzerland, where special instruments were used to determine their age using the uranium series method. Over time, uranium decays into other elements such as thorium and lead, allowing researchers to create a timeline of sea level documented in each deposit.

A complex software at Harvard University helped generate predictions using various ice models and Earth’s parameters to show an accurate history of sea level. These predictions are essential because they allow researchers to estimate past global mean sea levels, which is critical in addressing future sea level rise.

“If humans remain the main driver and temperatures rise by 1.5 degrees in the near future, there will be irreversible damage,” Onac said. “From that moment on, there is no going back.”

Hidden in caves: mineral vegetation reveals unprecedented modern sea level rise

USF Geology Professor Bogdan P. Onac explores the cave of Varques to investigate pre-industrial mineral vegetation. Credit: University of South Florida

Based on ice mass loss of Antarctica and Greenland, the average sea level rise since 2008 has been 1.43 millimeters per year.

Permanent flooding from rising sea levels won’t happen overnight, but Onac says it will be seen more and more during storm surges and hurricanes. With nearly 40 percent of the world’s population living within 62 miles of a coast, rising sea levels could be catastrophic with significant social and economic consequences.

“Even if we stop now, sea levels will continue to rise for at least a few more decades, if not centuries, simply because the system has warmed.”


Geoscientists reconstruct 6.5 million years of sea level levels


More information:
Bogdan P. Onac et al, Exceptionally stable pre-industrial sea level inferred from the western Mediterranean, scientific progress (2022). DOI: 10.1126/sciaadv.abm6185

Quote: Hidden in caves: Mineral overgrowth reveals unprecedented modern sea level rise (2022, June 30) retrieved June 30, 2022 from https://phys.org/news/2022-06-hidden-caves-mineral-overgrowths-reveal.html

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