Researchers from the Max Planck Society's Institute of Marine Microbiology have revealed the vital role that microorganisms in the Black Sea play in reducing emissions of nitrous oxide (N₂O), known as "laughing gas," a powerful greenhouse gas that destroys the ozone layer.
Jan von Arx, the study's lead author, explained that nitrous oxide is the third most abundant greenhouse gas and remains in the atmosphere for about 120 years. He added, "Since the oceans are a major natural source of N₂O, understanding the dynamics of its production and breakdown is essential for assessing the response of marine systems to climate change."
The results of the scientific expedition aboard the Poseidon vessel to the western Black Sea showed that the semi-oxygenated zone—the layer of water with low oxygen levels between the oxygen-rich surface and the oxygen-free depths—has an active nitrous oxide cycle. Microbes that reduce N₂O to N₂ act as a "biological barrier," preventing the gas from escaping into the atmosphere.
Von Arx pointed out that some microbes produce nitrous oxide, while others convert it into nitrogen gas, which makes emissions from the Black Sea very limited despite continued production in its surface layers.
Scientists warn that as global warming accelerates and oxygen levels in the oceans decline, low-oxygen zones may expand, potentially leading to increased nitrous oxide emissions in the future.
