This year, our ocean issue recognizes the United Nations Ocean Decade with a close look at the carbon cycle in the deep blue sea. In “Our Evolving Understanding of Biological Carbon Export” researchers analyze the processes and organisms that make up the biological carbon pump. Authors of the opinion “The Science We Need to Assess Marine Carbon Dioxide Removal” encourage scientists to develop standards for judging the effectiveness of carbon dioxide removal methods. Finally, with research presented at AGU23, we examine when and how carbonate corals made a new island in the Philippines. Dive in!
“Marine snow,” ubiquitous across the open ocean, comprises tiny (approximately millimeter-long) bits of organic detritus that accumulate and break down as they descend through the water column. This photo shows marine snow in the water surrounding jellies. Credit: Florian Olivo, Unsplash. Read more. 
Fig. 1. Various strategies for removing carbon dioxide from seawater and sequestering it for long periods of time have been proposed, each with its own considerations, complications, and potential durabilities. Credit: Mary Heinrichs/AGU. Read more. 
The researchers discovered an area of hidden coral biodiversity, called the Makkovik Hanging Gardens, by searching for underwater slopes and cliffs. Credit: Dave Cote, Fisheries and Oceans Canada. Read more. 
In a new study, researchers analyzed the basic oceanography of Marian Cove, a narrow fjord north of the Antarctic Peninsula. Credit: Cristian Coman/Imaggeo, CC BY-ND 3.0. Read more.
—Caryl-Sue Micalizio, Editor in Chief