Weiwei Fu’s paper published this week in Global Biogeochemical Cycles shows ocean oxygen minimum zones are poised for a wild ride over the next few centuries. First they will expand from warming, but then they may shrink far below current levels. Recovery of oxygen after 2200 does not necessarily bode well for ecosystems: the reversal in the hypoxia trend is driven by loss of nutrients from surface waters and decreases in marine productivity well below contemporary levels. The O2 recovers because the tropical ocean biosphere becomes more like a desert. This work is a nice illustration of a biological tipping point (one we don’t want to cross) and the value of exploring Earth system changes in deep future time!