Roofs in Seychelles are rusting - is the sea getting saltier?

Cousin Island Field Station in 1973 when thatched roofs didn't rust

“I don’t understand it. We just changed the entire roof two years ago and now we need to replace it” says Kerstin Henri, Nature Seychelles’s Director. Kerstin is talking about the international Field Station on Cousin Island Special Reserve which had been re-roofed with supposedly good quality pre-painted, galvanized iron sheets.

“Cheap Ch....se crap” was someone's response. That may be so but I have another theory. I think that the ocean around the Seychelles has become saltier.


My theory is supported by a paper published in the prestigious journal Nature in 2003. The paper says that the tropical Atlantic ocean has become saltier over a period of 40 years. These large-scale, rapid changes in the oceans seem to show that recent climate changes, including global warming, may be altering system that regulates evaporation and precipitation and cycles fresh water around our world Nature paper.

"This study is important because it provides direct evidence that the global water cycle is intensifying," said Elise Ralph, associate director of the US National Science Foundation's physical oceanography program, which funded the research. "This is consistent with global warming hypotheses that suggest ocean evaporation will increase as Earth's temperature does. These issues are particularly important as pressure on freshwater resources has become critical in many areas around the world."

This kind of change in the water cycle can affect global rainfall. In turn this will affect the distribution, severity and frequency of storms, floods and droughts. If more water is added to the atmosphere by these changes, global warming would intensify because water can trap heat.

Last year NASA created the first ever map ever which shows salinity levels in every ocean on the planet – and it could prove vital to understand everything from global rainfall to ocean currents.

NASA’s Aquarius/SAC-D satellite orbiting round Earth has been taking specialized radio measurements which have been put together to form an easy to understand map of the globe. The data will give scientists a new level of understanding about climatic patterns such as how freshwater is moving around, which influences ocean circulation NASA salinity map.

Definitely, the sea surrounding the granitic Seychelles has been more saline for quite a while than, say, the ocean around the Pacific islands. I remember visiting some model rooms for a new hotel some years ago and warning the architect that all the steel fittings would rust. Sure enough I was proven right. The wrong grade of stainless steel was used and the fittings corroded after less than a year. Now if it’s true that our sea has become even more saline, we have quite a lot to worry about and not just rusting fittings and roofs!

First published in The People, 20 September 2012