Oxygen and indicators of stress for marine life in multi-model global warming projections

[摘要] Decadal-to-century scale trends for a range of marine environmental variablesin the upper mesopelagic layer (UML, 100–600 m)are investigated using results from seven Earth System Models forced by ahigh greenhouse gas emission scenario. The modelsas a class represent the observation-baseddistribution of oxygen (O₂) and carbon dioxide (CO₂),albeit major mismatches between observation-based and simulated values remain for individualmodels. By year 2100 all models project an increase in SST between 2 °C and 3 °C, and a decrease inthe pH and in the saturation state of water with respect to calcium carbonateminerals in the UML.A decrease in the total ocean inventory of dissolved oxygen by 2% to 4%is projected by the range of models.Projected O₂ changes in the UML show a complex pattern with bothincreasing and decreasing trends reflecting the subtle balance of differentcompeting factors such ascirculation, production, remineralization, and temperature changes. Projectedchanges in the total volume of hypoxic and suboxicwaters remain relatively small in all models. A widespread increase of CO₂ in the UML is projected. The medianof the CO₂ distribution between 100 and 600m shifts from 0.1–0.2 mol m⁻³ in year 1990 to 0.2–0.4 mol m⁻³ in year2100, primarily as a result of the invasion of anthropogenic carbon from theatmosphere. The co-occurrence of changes in a range of environmental variables indicates theneed to further investigate their synergistic impacts on marine ecosystems and Earth System feedbacks.

[学科分类] 地球化学与岩石