A new review in Limnology and Oceanography led by scientists at UC San Diego's Scripps Institution of Oceanography warns that the rapid loss of oxygen from the ocean and other aquatic ecosystems is pushing Earth toward an "unsafe space," with consequences that could be irreversible on human timescales.

Alberto Borges, oceanographer at the University of Liège, has conducted a comparative study in Belgium and Africa on the microbial oxidation of methane in rivers, a natural process in which certain bacteria consume this powerful greenhouse gas before it is released into the atmosphere. His research reveals that this biological filter, which is more active in African rivers than in Belgian rivers, remains insufficient to offset the rise in methane emissions expected because of global warming and nitrate pollution.