“Tidal Influence: Methane Emissions from the North Sea Vary Dramatically”

Methane, a potent greenhouse gas, is known to naturally escape from the bottom of the North Sea. However, new research conducted by NIOZ oceanographer Tim de Groot has revealed that the amount of methane emissions can vary significantly depending on the pressure of high or low tide.

In a publication in Nature Communications Earth and Environment, De Groot highlights the importance of taking multiple measurements to accurately assess methane emissions from the seafloor. He emphasizes, “Our research shows that you can never rely on one measurement when you want to know how much methane escapes from the seafloor.”

Methane is produced when organic material in the seabed is broken down by bacteria in the absence of oxygen. This process occurs in old layers of organic materials at depths of up to 600 meters in the North Sea. Similar to swamp gas, methane can escape from the seafloor when the pressure reaches a certain level.

De Groot’s research near the Dogger Bank, located between Denmark and Scotland, revealed significant variations in methane emissions. Measurements taken at a bubbling methane source at a depth of forty meters showed that emissions can be three times higher or lower depending on the tide. This variation is attributed to the influence of high and low tides on methane release.

The study also found that methane emissions are lower in summer due to the activity of bacteria that consume methane and emit it as the less potent greenhouse gas CO2. In warmer and calmer waters, these bacteria have more time to convert methane into CO2, reducing the amount of methane that reaches the atmosphere.

While the warming of the climate may have a positive effect on methane consumption by bacteria, increasing storms could enhance methane emissions to the atmosphere. De Groot warns that taking measurements only during high tide or in the summer may lead to underestimating methane emissions from the seafloor. He stresses the importance of regular measurements in different seasons to obtain an accurate picture of methane emissions.

Overall, De Groot’s research serves as a cautionary tale for scientists studying methane emissions from the seafloor. By considering the influence of tides and seasons on methane release, researchers can better understand the impact of this potent greenhouse gas on the environment.