Quartz: “On January 5, 2018, a paper published in the journal Science delivered a sobering message: The oxygenation of open oceans and coastal seas has been steadily declining during the past half century. The volume of ocean with no oxygen at all has quadrupled, and the volume where oxygen levels are falling dangerously low has increased even more. We’re seeing the same thing happen in major lakes. The main culprits are warming and—especially in coastal seas and lakes—eutrophication caused by enhanced nutrient loads in runoff. The findings reaffirm that we urgently need to address global warming, and that we are in need of an updated Clean Water Act. We only need to look to the Mediterranean Sea and, more recently, the North American Great Lakes region for dramatic illustrations of what lies in store if we don’t act now…”

Beneath the waves, oxygen disappears – “As plastic waste pollutes the oceans and fish stocks decline, unseen below the surface another problem grows: deoxygenation. Breitburg et al. review the evidence for the downward trajectory of oxygen levels in increasing areas of the open ocean and coastal waters. Rising nutrient loads coupled with climate change—each resulting from human activities—are changing ocean biogeochemistry and increasing oxygen consumption. This results in destabilization of sediments and fundamental shifts in the availability of key nutrients. In the short term, some compensatory effects may result in improvements in local fisheries, such as in cases where stocks are squeezed between the surface and elevated oxygen minimum zones. In the longer term, these conditions are unsustainable and may result in ecosystem collapses, which ultimately will cause societal and economic harm…”