IMAS scientist urge caution on ocean C02 removal methods

In a new paper published in Environmental Research Letters, a team of international researchers including scientist from the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS) reviewed the effectiveness of four nature-based techniques that use marine biological processes to remove CO2.

These include seaweed farming, shellfish cultivation, increasing whale populations through re-wilding, and coastal blue carbon captured by restoring seagrass, saltmarsh, and mangrove forests.

IMAS oceanographer Phillip Boyd said limiting warming to less than 2 degrees required both emissions reductions and CO2 removal.

"But multiple techniques need to be developed and massively upscaled to achieve that goal," Dr Boyd said.

While new methods are being proposed regularly, the study team says there are "insufficient checks and balances" in place.

"This is particularly true for ocean-based CO2 removal, which is attracting greater interest as the constraints on land-based methods become increasingly apparent," Dr Boyd said.

The study team said the ocean-based approaches they've reviewed are being advocated not only by scientists but, in many cases, also by the private sector, without due diligence on the "underpinning fundamental science".

"Those advocating these approaches have given insufficient attention to basic constraints relating to ecosystem functioning and the ocean carbon cycle," Dr Boyd said.

"There is a need for better communication of the basic criteria for viable CO2 removal through marine processes.

"Safety and durability, and being verifiable and scalable, should be considered when prioritising relevant research and development funding by governments, as well as providing checks and balances for policymakers."