Speed Up Oceanic Carbon Sequestration, to Fight Climate Change

It has been almost a year since carbon dioxide in the earth’s atmosphere surpassed the 400 parts per million (PPM) mark, which some scientists and environmental activists say is a “tipping point” in the struggle to curb climate change. With that 400 PPM mark in mind, the global conversation that comprises electric cars and the development of new clean technologies also includes carbon sequestration, often touted as a way to limit the increase in global temperatures to 2°C this century by sucking carbon out of the atmosphere.

The International Energy Agency (IEA), for example, declared last month that carbon capture and storage (CCS) is crucial in order to slow rising temperatures this century. While projects have developed worldwide, from Abu Dhabi to Norway, critics of this technology repeatedly say that the high expense of this technology is not worth the investment.

But what about storing carbon in the world’s oceans?

The idea of oceanic carbon sequestration has been described by one science writer as “the world’s best bad idea.” No, carbon captured from fossil fuels and other carbon-intensive industries would not just be dumped into the sea. For example, researchers from Harvard University and Columbia University a decade ago suggested that carbon dioxide could be pumped a few hundred yards into the sea floor in deeper regions of the ocean. Those scientists suggested carbon be stored at depths of at least 3,300 feet, where low temperatures and high pressure would prevent that CO2 from dissipating and killing marine life. As in the case with most carbon sequestration ideas, however, this theory worked well on paper or in the lab, but in reality could not scale.

Now scientists at the California Institute of Technology and University of Southern California believe they have found a way to bring oceanic carbon sequestration closer to reality.

The key is carbonic anhydrase, an enzyme that can quickly catalyze CO2 into bicarbonate and other protons. Cal Tech’s Jess Adkins and USC’s William Berelson became curious about the role of calcite in the world’s oceans. Calcite, comprised of calcium, carbon and oxygen, is critical in the formation of limestone and granite, and is also found in shellfish, plankton and the exoskeletons of coral.

Adkins, Berelson and their research team bio-engineered a sample of calcite similar to how it forms in oceanic environments, and dissolved it in seawater. They then added carbonic anhydras, and found that that the enzyme sped up the chemical reaction that helps the ocean sequester CO2 by a rate 500 times faster than how it would occur naturally.

“The implication is that we might better mimic the natural process that stores carbon dioxide in the ocean," said Caltech graduate student and the study’s lead author, Adam Subhas, to Phys.org.

Does this mean we are ready to build pipelines of CO2 to the world’s oceans? Probably not, as the question of how bad ocean acidification is wreaking havoc on the oceans worldwide still generates lively debate within the scientific community. But this research can inspire more research on innovations that can help the earth confront climate change. “Novel molecular structures are a first step toward economical carbon capture at a wide scale,” said Richard Martin in a September 2015 article on MIT Technology Review.

Image credit: Leon Kaye