Introduction to special issue

Oceans of change

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Science  13 Nov 2015:
Vol. 350, Issue 6262, pp. 750-751
DOI: 10.1126/science.350.6262.750

In Malé, the capital of the Maldives, more than 120,000 people live just a meter or so above current sea level.

PHOTO: GEORGE STEINMETZ

The phrase “climate change” typically evokes thoughts of rising air temperatures or other atmospheric phenomena such as droughts and extreme storms. Much less often do we consider the parallel changes that are occurring in the oceans, despite their extent and importance.

Climate change in the oceans has many facets. One is a rise in sea levels. Scientists are learning about how previous warm periods altered sea levels, and what that past may tell us about the future. To help us cope, so-called green infrastructure, such as planted marshes or oyster reefs, may help protect low-lying shorelines. Climate change is also creating problems for fisheries; for example, commercially valuable stocks move in response to warming seas.

Climate change has caused ocean temperatures to rise, a trend that will continue in the coming centuries even if fossil fuel emissions are curtailed. The uptake of carbon dioxide also makes the oceans more acidic, affecting the ability of organisms to create and maintain calcium-based shells and skeletons. Warm-water corals are particularly susceptible to these effects and may not survive the century unless carbon emissions are greatly reduced. Climate change impacts in the deep ocean are less visible, but the longevity and slow pace of life in the deep makes that ecosystem uniquely sensitive to environmental variability. Marine vertebrates at every depth are being affected, as are humans. Even if international negotiations like those kicking off soon in Paris succeed, we will be coping with the impacts of ocean climate change for centuries.

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