Geophys. Res. Lett. 38, L24608 (2011)

Very-low-oxygen (hypoxic) zones occur in many coastal waters. These so-called dead zones have spread rapidly since the 1960s owing to human-induced nutrient enrichment, and pose a serious threat to coastal systems worldwide. An important question is whether climate change will enhance or attenuate this existing environmental problem.

To investigate this issue, Markus Meier, from the Swedish Meteorological and Hydrological Institute, Sweden, and co-workers used modelling experiments to quantify the potential influence of climate change on oxygen conditions in the Baltic Sea over the twenty-first century.

Their results indicate that climate warming will very likely exacerbate existing hypoxic areas in the Baltic Sea, with a slight reduction in hypoxia only brought about by assuming optimistic reductions in nutrient load. These results were consistent regardless of the global climate model and carbon-emissions scenario employed, which improves confidence in the findings. The authors suggest that similar expansion of hypoxic zones can be expected for other coastal waters worldwide.