Decadal Scale Variability of Oxygen Minimum Zones in the Atlantic and Pacific Oceans

For the first time, a study documents long-term, large-scale Oxygen Minimum Zone (OMZ) variability since the 1950s based on historical oceanographic data from the World Ocean Atlas 2009. This study provides a baseline to quantify the magnitude of OMZ water volume and area changes in the Atlantic and Pacific Oceans on decadal time scales for 3 DO2 ranges (d45, d61, and d90 µmol kg-1). Positive linear trends of volume and area superimposed on large decadal-scale fluctuations were observed at all DO2 thresholds except for the d90 µmol kg-1 threshold in the Pacific. Heat content and DO2 content variability within the OMZ exhibited a high degree of correlation, particularly in the Atlantic at all DO2 thresholds. Large fluctuations in the extent of OMZ have major biological and socio-economic implications. Additional work is needed to quantify the changes, the ecosystem response scenarios, and the mechanistic role of physical processes including water-mass transport variability