PARIS • Hydrocarbon gases bubbling from the bottom of the Red Sea are polluting the atmosphere at a rate equivalent to the emissions of some large fossil fuel exporting countries, researchers have said.

The gases seeping from the waters - which are ringed by the resorts and ports of several countries, including Egypt, Israel, Jordan and Saudi Arabia - then mix with emissions from industrial shipping and turn into noxious pollutants that are very harmful to human health.

During a 2017 expedition around the Gulf, researchers at the Max Planck Institute for Chemistry noticed that levels of ethane and propane in the air above the Northern Red Sea were up to 40 times higher than predicted, even accounting for regional man-made emissions.

The team came to an unexpected conclusion: The two gases have to be seeping out of the sea bed after escaping natural subterranean oil and gas reservoirs.

They are then carried by currents to the surface, where they mix with another greenhouse gas, nitrous oxide, which is emitted in high amounts by industrial shipping.

The resulting gas compounds are extremely harmful to human health, according to the team's study, published in Nature Communications.

"I have to admit that I was surprised myself with these results," lead author Efstratios Boursoukidis said on Tuesday.

"We spent almost two years working on this data set to confidently prove that the emissions were coming some 2km below the sea surface."

The team calculated that the rate of ethane and propane leakage was comparable in magnitude to those of several hydrocarbon exporting nations, such as the United Arab Emirates and Kuwait.

The emissions result in another source of atmospheric methane, a potent greenhouse gas, the study said.

The situation is exacerbated by nitrous oxide pollution from the large number of shipping containers passing through the Northern Red Sea, one of Earth's busiest transport lanes.

And it is only likely to get worse as the route gets busier.

"In the coming decades, ship traffic through the Red Sea and Suez Canal is expected to continue to increase, with a concomitant rise in nitrogen oxide emissions," said Dr Boursoukidis.

AGENCE FRANCE-PRESSE