According to a new study published in the journal Nature Geoscience, fjords, deep narrow estuaries, have shown to play a crucial role in regulating carbon levels and combating climate change. Fjords absorb about 18 million tones of carbon annually, which is equivalent to 11 percent of annual marine carbon burial globally.

Scientists have known for a while that fjords play an important role in carbon storage in coastal environments, but because they only make up about 0.1% of the world’s oceans, no one realized just how much so until now. Dr Candida Savage of New Zealand’s University Otago, one of the study’s authors, and her colleagues calculated fjord organic burial per unit area and they found that it is actually twice as large as the ocean average. “As deep and often low oxygen marine environments, fjords provide stable sites for carbon-rich sediments to accumulate,” said Dr. Savage.

Dr. Savage and her team conducted fieldwork in Fiordland, an immense stretch of mountainous terrain in the south-west corner of the South Island of New Zealand. They also conducted research on nearly all of the world’s fjord systems, analyzing data from 573 surface sediment samples and 124 sediment core samples.

“The Earth is currently in an interglacial period after ice sheets receded around 11,700 years ago. During glacial retreats, fjords would trap and prevent large volumes of organic carbon flowing out to the continental shelf, where chemical processes would have caused carbon dioxide to be produced,” Dr Savage said.

“Once glaciers started advancing again this material would likely then be pushed out onto the shelf and carbon dioxide production would increase.”

“In essence, fjords appear to act as a major temporary storage site for organic carbon in between glacial periods. This finding has important implications for improving our understanding of global carbon cycling and climate change,” she said.

“Carbon sequestration is the big buzzword, but we’re still getting a handle on how it works. In order to make informed land-use decisions and accurate climate predictions, finding and understanding these hot spots is critical,” added co-author Dr Thomas Bianchi of the University of Florida.

Carbon burial is a very important process for keeping atmospheric carbon dioxide at manageable levels. This study suggests that  fjords play a very important role in regulating atmospheric carbon dioxide levels, especially during times when ice sheets are advancing or retreating, like is happening today.