Decades of research show the waters around Bermuda becoming warmer, saltier and more acidic.

A recent paper based on observations collected from two locations off the island’s coast said waters had increased in temperature by about 1C since 1983.

However, Nicholas Bates, a researcher at the Bermuda Institute of Ocean Sciences and co-author of the report, told Frontiers in Marine Science that rising water temperatures were only one of the changes recorded.

During the same period, the amount of available oxygen in the water fell by 6 per cent and the ocean has become 30 per cent more acidic.

Dr Bates said: “The ocean chemistry of surface waters in the 2020s is now outside of the seasonal range observed in the 1980s and the ocean ecosystem now lives in a different chemical environment to that experienced a few decades ago.

“These changes are due to the uptake of anthropogenic carbon dioxide from the atmosphere.”

The research also highlighted increased salinity of surface waters near the island.

“We suspect this is part of the broader, more recent trends and changes in ocean temperatures and environmental changes, like atmospheric warming and having had the warmest years globally,” Dr Bates said.

Data from the Bermuda Atlantic Time-series Study, which collects observations from a location around 80km southwest of Bermuda, found that ocean surface temperatures have increased by about 0.24C a decade since the 1980s.

The figures also showed a sharper rise in the past four years compared with earlier decades.

A similar pattern emerged with the salinity of surface waters, with salt levels found to have “disproportionally increased” in recent years.

Both the heightened salinity and the lower oxygen are believed to be linked to the increased temperatures in the Atlantic.

Oxygen dissolves less easily in warmer waters and changes in air and ocean temperatures can impact the rate that ocean waters evaporate, affecting the amount of salt in the water.

Meanwhile, ocean acidification has been linked to the ocean’s absorption of carbon dioxide in the atmosphere.

Dr Bates said that climate change would affect other ocean systems in different ways and the impact of the changes on the Sargasso Sea remained uncertain.

However, he noted that the long-term data collection provided scientists with a useful tool to forecast future changes.

“These observations give a sense of the rate of change in the recent past of ocean warming and ocean chemistry,” he said.

“They provide key indications of future changes in the next decades.

“They also are proof of regional and global environmental change and the existential challenges we face as individuals and societies in the near future.”

The paper noted that the BATS records are among only a few longer than 20 years in duration, but in recent decades ocean observations have been established in other locations to paint a better picture of the challenges facing oceans.

“There will be a pressing need to combine, compare and synthesise ocean carbon and biogeochemical data for both highest-quality climate trend data analyses and local, regional and basinal data synthesis,” the report said.

“Such efforts will have challenges associated with data/time-series context and combining different types of data/sensor streams to allow for consistent and comparable synthesis.”