Researchers globally utilize ocean monitoring technologies to assess climate change impacts. A team from the University of Alaska Fairbanks and their industry collaborators have improved the methods for detecting carbon dioxide in ocean waters. Their recently published design in the journal Ocean Science is now accessible to the scientific community.
Over the last six years, a collaborative group from the UAF International Arctic Research Center, along with private industry partners, developed a system to equip an autonomous underwater vehicle known as a Seaglider with a carbon dioxide monitoring sensor. This sensor communicates via satellite, delivering high-resolution data continuously for several weeks. The ongoing data stream provides scientists with a comprehensive understanding of the ocean’s chemical makeup, although the process required significant innovation.
The industry collaborators, Advanced Offshore Operations and 4H JENA Engineering, worked on reducing the weight and size of the Contros HydroC sensor, enabling it to fit onto the Seaglider.
Despite this progress, the sensor remains bulkier and requires more energy than usual sensors for the Seaglider. Thus, the team meticulously accounted for its impact on buoyancy, using weights and 3D-printed materials to make adjustments.
Claudine Hauri, an oceanographer and deputy director at IARC, noted that monitoring CO2 levels in the ocean provides essential data for crafting climate change adaptation strategies.
Carbon dioxide is a greenhouse gas emitted from burning fossil fuels like coal, oil, and gas, and contributes to global warming by trapping heat in the atmosphere. The ocean has played a crucial role in alleviating climate change effects, absorbing about one-third of the CO2 emissions since the beginning of the industrial age. However, this has resulted in ocean acidification.
“When atmospheric carbon dioxide dissolves in ocean water, it lowers the pH, causing ocean acidification,” Hauri explained. “Such conditions can hinder various marine species from forming and maintaining their shells, and can even impact fish populations.”
Building on their success with the CO2 sensor, the team has now turned to studying another greenhouse gas—methane. They have equipped a Seaglider with a methane detection sensor, which is currently undergoing testing.
Although methane doesn’t persist in the environment as long as carbon dioxide does, it has a much stronger heat-trapping ability. Approximately 60 percent of methane emissions are human-induced, stemming from agriculture, waste management, and fossil fuel extraction, while the remainder occurs naturally, including from the ocean where it escapes from the Earth’s deepest areas.
Methane hydrates, which are trapped in undersea permafrost and mixed with sediments on the ocean floor, can be destabilized by rising water temperatures. When this happens, methane is released into the water column, where microorganisms can convert it into carbon dioxide, potentially leading to events of ocean acidification.
Hauri mentioned that the Seaglider team faces another hurdle: overcoming the harsh conditions of Alaskan waters.
“The Seaglider we are currently using isn’t particularly suited for the coastal oceans of Alaska,” she remarked. “We are seeking an autonomous underwater vehicle that can endure these conditions. Once we find one, we’ll integrate it with the CO2 and methane sensors to gather data from some of the most isolated areas on the planet, enhancing our understanding of the ocean’s chemical processes.”
