Last year, some surprising findings were published in Nature Geoscience. A research team led by Prof. Sweetman explored a deep-sea area between Hawaii and Mexico, where they planted sensors over 5 kilometers (about 3.1 miles) deep. This part of the ocean floor is rich in metal nodules, which are formed by dissolved metals in seawater gathering around shells and other materials over millions of years.
The sensors detected something unusual: rising oxygen levels. Initially, Prof. Sweetman dismissed it because he believed oxygen only comes from photosynthesis. However, he and his team decided to investigate further. In their lab, they tested the nodules in seawater and discovered that these metallic lumps could actually generate oxygen. They found that the nodules created electric currents that split seawater into hydrogen and oxygen.
Not everyone agreed with their findings. Critics, including Michael Clarke from a Canadian mining company, argued that there was no real oxygen production—just bubbles from the sampling process. Prof. Sweetman countered that their experiments could prove otherwise.
This debate matters because major mining companies are eager to extract these metal nodules from the ocean floor. The metals found there are crucial for batteries, which are seeing increased demand as the world shifts towards electric vehicles and moves away from fossil fuels.
However, this push for seabed mining has raised alarms among environmentalists and scientists. Over 900 marine experts from 44 countries have signed a petition warning about the environmental risks and calling for a halt in mining activities.
During a recent press conference, Prof. Sweetman emphasized the need for care, stating, “Before we do anything, we need to understand the deep-sea ecosystem as best as possible.” He believes it’s essential to pause and evaluate the global implications of these actions.
