Climate models have also predicted large-scale declines in oceanic oxygen. As surface waters warm up, they become less efficient at absorbing oxygen and act as a cap, preventing the mixing of oxygen into deeper layers. If upwelled into coastal regions, these deep waters—depleted in oxygen but rich in nutrients—may prime local areas for hypoxia. Studies have documented a drop in oxygen levels across the Pacific Ocean, possibly contributing to the emergence of hypoxia in Oregon.
The primary challenge facing scientists is lack of sufficient long-term data for upwelling systems, states Jane Lubchenco, an Oregon State marine ecologist. A recent symposium highlighted the urgent need for more monitoring, as well as the importance of continued communication among scientists. “It is clear that these systems are not exactly alike,” Lubchenco notes, but comparing them may help researchers figure out how hypoxia develops. Ultimately, predicting future changes will be crucial in determining if—or more likely, when—expanding low-oxygen zones might choke fisheries worldwide.
Note: This article was originally printed with the title, "Suffocating Seas".