The bottom of the sea can be a rather difficult place.
Underwater volcanoes and vents along the faults emit significant quantities of underwater gas including CO2, carbon dioxide.
Endless armies of bacteria make up dead marine creatures in natural methane.
And new Japanese research shows us huge reserves of greenhouse gases spread just below the seabed.
In a study published last month in the scientific journal Geophysical Research Letters, a research team has discovered one of these deposits under a basin located at the meeting point between Japan and the Philippines. By analyzing seismic data to map the fault structure, the team has identified a huge "pocket" of gas that extends for about 4km in length and which can contain more than 100 million tons of CO2, methane or a mix of the two.
Resource or danger?
It depends on the content. This huge underwater gas field can represent an energy opportunity, but also a huge bomb of greenhouse gases ready to release into the atmosphere (as if we were not already in bad shape).
If the gas in the bag is CO2 only, I estimate it in quantities of around 50 million tonsTakeshi Tsuji, Kyushu University's International Institute for Carbon-Neutral Energy Research.
A cross-section is the amount equivalent to the annual CO2 emissions of all private cars in Japan.
Tsuji and his colleagues navigated scientific vessels along the affected stretch of sea, using a device to generate small seismic waves from various angles. By measuring the variations of these waves as they passed to the seafloor, the team then profiled what lies beneath.
“Waves of this type usually travel slower in gases than through solids,” says the study's co-author Andri Hendriyana, also a researcher at the International Institute for Carbon-Neutral Energy Research. "By examining the speed of these waves we have identified these huge reserves, and we are trying to get information on how saturated these gases are."
The "blob" of underwater gas is there, in short. And like him under the bottom of the sea there are others, even bigger ones (as well as fresh water reserves).