Ocean Science

Refuges for Corals

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Science  27 Jul 2012:
Vol. 337, Issue 6093, pp. 391
DOI: 10.1126/science.337.6093.391-d
CREDIT: THINKSTOCK

Global warming presents a real and present danger to coral reefs, owing to the increasing frequency of bleaching events as water temperatures rise. In the central Pacific, for instance, sea surface temperatures are projected to increase by nearly 3°C by the end of this century, a rise that could be devastating to many of the rich marine ecosystems that thrive there. However, the climate system is complex and heterogeneous in its response to global warming, particularly at smaller scales, and there should be regions in which surface ocean warming is less pronounced than others. Karnauskas and Cohen report that warming around some Pacific islands could be mitigated by enhanced upwelling caused by the strengthening of the equatorial undercurrent, which models predict will occur. Less warming should translate into less severe negative impacts on the coral reefs and rich ecosystems in those locations, potentially providing vital refuges in otherwise more hostile environmental conditions. Although few coral reefs may benefit from this island effect, because the equatorial undercurrent flows only around the Equator, knowing where refuges could exist might help planning efforts to protect them in ways that we can control.

Nat. Clim. Change 2, 530 (2012).

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