Thursday, May 11, 2017

Due to Accelerating Greenhouse Effect, Oceans Are Recently Losing More Oxygen, with Deeper Water Masses Leaking Even Further

We know global oceans are absorbing 93 % of increased Earth’s heat content due to greenhouse effect, which are caused by anthropogenic emissions of greenhouse gases such as carbon dioxide (CO2) and methane (CH4). Are those oceans just very generous bottomless sinks of global heat with no side effects? Of course, “NO”. They have been leaking oxygen into the atmosphere, possibly due to the rising water temperature.

The finding comes from a recent paper published in the journal Geophysical Research Letters. Historic observations of dissolved oxygen (DO) in the global oceans from 1958 to 2015 quantitatively prove a significantly negative correlation between the DO and ocean heat content (OHC). Yes, our oceans are losing oxygen.

Sounds familiar? But, this study goes further. It shows that deeper water is losing more oxygen than the water at shallower depths. The reason? Deeper ocean is storing more heat. I regret that I cannot show the disturbing graphs here. Check out the paper by clicking the link below.

Reference: Ito, T., Minobe, S., Long, M. C., & Deutsch, C. (2017). Upper Ocean O2 Trends: 1958–2015. Geophysical Research Letters, (In Press), n/a–n/a. [Full-text at]

Figure: Global map of the linear trend of dissolved oxygen at the depth of 100 meters. (Credit: Georgia Tech)