Research Team Designs Technology to Measure Carbon Dioxide in Oceans

A Seaglider. Photo: Hydroid, Inc./Kongsberg Maritime.

New technology developed by University of Alaska Fairbanks researchers and their industry partners would enable an unmanned underwater vehicle to measure carbon dioxide in the ocean in order to help develop climate change adaptation plans.

The design is now available to the scientific community, researchers at UAF’s International Arctic Research Center said Nov. 26. It was published Oct. 29 in the journal Ocean Science.

Over the past six years, a team from the UAF International Arctic Research Center (IARC) and private companies developed a way to equip an Autonomous Underwater Vehicle (AUV) called a Seaglider with a sensor that monitors carbon dioxide. 

The sensor communicates with a satellite to provide high spatial and temporal resolution data for weeks at a time. This continuous flow of data, which gives scientists a clear picture of ocean chemistry, took some ingenuity to bring together, researchers said.

Monitoring carbon dioxide levels in the ocean creates the information needed to develop climate change adaptation plans, said Claudine Hauri, the team’s oceanographer and IARC’s deputy director.  

One challenge the Seaglider team still faces is extreme conditions in waters around Alaska. 

“The Seaglider we’re using isn’t really made for Alaska’s coastal oceans,” she said. “We’re looking for an autonomous underwater vehicle that can withstand the elements. Then we’ll integrate it with the carbon dioxide and methane sensors to collect data from some of the most remote spots on Earth, furthering our understanding of chemical processes in the ocean.”

IARC’s industry partners—Advanced Offshore Operations and 4H JENA Engineering—made the Contros HydroC sensor lighter and more compact so it would fit the Seaglider.

The sensor is still larger and demands more power than those typically used on a Seaglider, so the team had to carefully account for its effects upon buoyancy and adjust by using weights and 3D-printed materials.

Carbon dioxide, released when humans burn coal, oil and gas, is called a greenhouse gas because it traps heat in the atmosphere and contributes to climate warming. The ocean has slowed the effects of climate change by absorbing about a third of carbon dioxide emissions since the industrial revolution began, but that has led to ocean acidification. 

Hauri noted that when carbon dioxide from the atmosphere dissolves into the ocean, it decreases the pH, leading to ocean acidification and making it difficult for some marine organisms to maintain their shells. Fish also may be affected, she said.

“While I can’t speak specifically to this study, all work to improve our understanding of climate change impacts to the ocean and the fisheries managed by the council can help all of us (managers, communities, individuals) make more informed decisions,” said Katie Latanich, the climate project manager for the North Pacific Fishery Management Council in Anchorage.

“From our vantage point in the management process, our task is to work with our scientific partners to connect climate science with the decision-making process, and this is one focus of the council’s current climate readiness planning,” she said.

In the wake of their technological success with the carbon dioxide sensor, researchers tried monitoring another greenhouse gas, methane. While methane doesn’t stay in the environment as long as carbon dioxide, it does trap more heat. Roughly 60% of methane emissions are from agriculture, waste and fossil fuel industries. The rest occur naturally, including in the ocean where it bubbles to the surface from the deepest parts of the Earth.

Seagliders, initially developed at the University of Washington, measure temperature, salinity and other quantities in the ocean, sending back data using global satellite telemetry.

Seaglider AUVs are in use worldwide, collecting oceanic physical properties and performing various other missions for oceanographers, including the U.S. Navy, government agencies and research organizations.