What did we do? We analyzed outputs from the Community Earth System Model Large Ensemble to examine the century-scale trend of dissolved oxygen in the mid-depth part of the global oceans. The Large Ensemble included 24 simulations of global climate from 1920 to 2100, and allowed us to determine the Time of Emergence (ToE) when the human-induced signal exceeds the natural variability.
What did we find? We likely to observe widespread anthropogenic ocean deoxygenation by 2030-2040s.
Why is it important? Ocean is the dominant heat sink in the climate system, and it is heating up due to the global warming. The increasing temperature and stratification is predicted to drive oxygen decline in the seawater – aka Ocean Deoxygention. We care about the oxygen level of the oceans because it is an important factor shaping the habitats for all marine mammals, fish, shellfish, and multi-cellular organisms.
Reference: Long M., C. Deutsch and T. Ito, (2016), Finding forced trends in oceanic oxygen, Global Biogeochemical Cycles, doi:10.1002/2015GB005310