Aquatic Deoxygenation

Extract

• Crossing Planetary Boundaries (PB)—a concept that defines nine potential ecological “tipping points”—could spell doom for ecosystems and humanity’s future on the planet.
• Of these PBs, humans have already crossed six of the nine thresholds.
• Now, scientists are arguing that there’s potentially a tenth boundary that’s gone unrecognized, which concerns worldwide aquatic deoxygenation in lakes, reservoirs, oceans, and other bodies of water.

“Climate change” is a scary, catch-all term that summarizes all the anthropogenic degradation humans are inflicting on the planet. In reality, climate change is only one of the many threats facing the planet.

First introduced in 2009, the Planetary Boundary (PB) concept identifies nine unique thresholds that could spell disaster if humanity crosses them. While climate change is one of the nine boundaries, the list also includes things like biosphere integrity, ozone depletion, ocean acidification, freshwater change, and more. (Of course, what we think of as climate change exacerbates all of these issues, so in a sense, it remains Public Enemy No. 1.)

Now, scientists argue that a 10th boundary could be added to the list: aquatic deoxygenation. Some bodies of water in the world (such as basins in the Black Sea, the Baltic Sea, and various fjords) are naturally anoxic, meaning that they contain little or no oxygen. But widespread deoxygenation is different, as it affects previously oxygenated bodies of water globally and to varying degrees.