One would expect the massive Middle Eastern petroleum industry to affect air quality over the whole region, including the Red Sea – and it does. But scientists on a 2017 shipping expedition in the Arabian Peninsula were astonished to discovery that ethane and propane levels in the northernmost Red Sea were up to 40 times higher than predicted.
Around the world, atmospheric concentrations of ethane and propane correlate with industrial activity, and the oil industry and pollution from gas flares can explain high concentrations over the Arabian Gulf and Suez Canal. But anthropogenic elements couldn't explain the high levels of propane and ethane over the northern Red Sea. Some agency other than industry was at play, and on Tuesday the explanation was published in Nature Communications.
To their surprise, deep analysis found the answers at the bottom of the Red Sea. Israel isn't affected because it is upwind from the emissions point, lead author Dr. Efstratios Bourtsoukidis of the Mainz-based Max Planck Institute for Chemistry (which also organized the expedition) tells Haaretz. The affected areas are mainly southern Egypt's Red Sea coast, Sudan, and Saudi Arabia.
The amount of gases rising from the seabed is comparable to the total anthropogenic emissions from entire individual Middle Eastern countries such as Iraq, the United Arab Emirates and Kuwait, the team reports.
But whence is this gargantuan emission of gaseous hydrocarbons from the seabed? The Red Sea lies between the Arabian and African continental plates, Bourtsoukidis explains. The southern Red Sea floor has been spreading for the past 5 million years, while the northern part is in a stage of continental rifting. Tectonic and seismic movements fracture the seafloor, which can potentially cause emission bursts.
More emissions come directly from dense super-saline water on the seafloor rising surface-ward, bringing gases seeping from hydrocarbon reservoirs – and from leaking wells.
In short, much of the "surplus" gas is natural in source, but there is an anthropogenous contribution. The magnitude of each contribution remains to be determined, Bourtsoukidis qualifies. But it seems that their cumulative contribution represents the missing source of the huge gas concentrations above the northern Red Sea, the team says.
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This phenomenon is unique to the Red Sea, Bourtsoukidis confirms to Haaretz. This makes sense: The Middle East has more than half of the planet's known oil and gas reserves.
And is there a problem with these gas concentrations? There might not be, if not for the shipping industry.
"In pre-industrial times, the underwater emissions of ethane and propane would not have had significant implications for regional air quality," Bourtsoukidis says. But among the pollutants ships emit are nitrogen oxides in gas form. These react with the ethane and propane, producing tropospheric ozone and peroxacyl nitrates – both of which damage our health, he says.
About the ozone: The troposphere is the lowest layer of the atmosphere, up to about 10 kilometers (6 miles) in altitude, and that ozone (O3) is unstable and toxic to flora and fauna alike. The "good" ozone layer that protects us from cancer-causing ultraviolet radiation, which science has been worrying about for decades, is 20 to 30 kilometers in altitude. As for the peroxacyl nitrates, they irritate our lungs and eyes, Bourtsoukidis explains.
The bottom line is that part of the problem stems from the natural riches of hydrocarbons in the local rocks and plate tectonics, which can't be solved. And since shipping through the Red Sea and Suez Canal is only expected to increase, we can expect a concomitant rise in nitrogen oxide emissions, Bourtsoukidis warns. That translates into deteriorating air quality.
The measurements took place in summer time. Considering the seasonality of the deep-water circulation, it is likely that the emissions to the atmosphere will be further enhanced during the wintertime, the team writes.
"The upwelling of the intermediate and deep water takes place in the narrow band along the Egyptian coast," Bourtsoukidis says – and it has a seasonal aspect: "The upwelling is weaker in summer compared with the winter, since atmospheric cooling drives the open water convection and enhances the vertical mixing in the water column," he adds.
Finally, let us be clear about something. "The newly discovered source should not be directly compared with the environmental impacts of the oil and gas industry in the Middle East, since these are emitting many more atmospheric pollutants," the scientists drive home.
However, the team recognized in the course of its 20,000-kilometer sailing mission – traversing the Mediterranean Sea, the Suez Canal, the Red Sea, the northern Indian Ocean and the Arabian Gulf, and back again – that the petroleum industry couldn't be the source of anomalies in the air. Which doesn't absolve them – including Israel's new massive gas-mining and production industry in the Mediterranean – of other ills.