The increasing concentration of atmospheric CO2 is thermally and chemically impacting the ocean and its ecosystems. If current trends continue, mean atmospheric CO2is expected to exceed 500 ppm by 2050 — a more than 80% increase above pre-industrial (pre-1750) levels1. This rate of increase seems to have few, if any, parallels in the past 300 million years of Earth’s history2. By mid-century the consequences of such an increase are projected to result in a global mean warming of at least 2 °C (ref. 1) and a >60% increase in mean surface ocean acidity3 that will have occurred over a span of just three centuries. Both the magnitude and rapidity of these changes is likely to surpass the ability of numerous marine species to adapt and survive4. Impacts are being and will be felt from tropical to polar oceans3, 5, 6, 7, although regional and ecosystem differences in forcings and biological responses are anticipated. Coral reef ecosystems and associated fisheries are likely to be particularly affected by the thermal and chemical changes8, 9, 10, 11, 12, 13, 14, 15, 16, with trillions of dollars in economic benefit at risk globally17, 18, 19, not to mention the threats to environmental services provided by the ocean that directly contribute to Earth’s habitability. Our concern is that the specific actions to counter such impacts as identified in current policy statements will prove inadequate or ineffective. Therefore, a much broader evaluation of marine management and mitigation options must now be seriously considered.

Rau G. H., McLeod E. L. & Hoegh-Guldberg O., in press. Nature Climate Change. doi: 10.1038/nclimate1555. Article.