2010: hottest year, Caribbean coral bleaching record

There is some big climate news under way. Negotiators in Cancún however can consider themselves fortunate that it will be at least another month before NASA scientists can announce their findings: 2010 will be the hottest year on record.

This confirms what climatologists have been saying all along: there is no downward trend from 1998’s El Niño record – and there has never been one. (Also 2005 came very close to breaking the record – according to some datasets that year was hotter already.)

Of course you can count on us for further coverage on the matter. No doubt there will be another nice graph to show.

Before all the temperature statistics are in nature already shows us it’s been a devastating year. A NOAA coral research group that investigated the 2005 bleaching event in a new publication in PLoS ONE state this year, at least in the Caribbean, shows the biggest die-off of coral algae, caused by heat stress and leading to bleaching and erosion of coral reefs (the coral polyps live in symbiosis with the coral algae: without the algae also the polyps start to die).

In total 80 percent of Caribbean coral was found to have bleached over the year 2010 and locally 40 percent of the coral actually died. Coral bleaching was also found to take place in all the other coral harbouring regions of the world, notably the Persian Gulf, Southeast Asia and the Central Pacific.

Acidification, that other threat to coral

Coral is not only threatened by warming of the world’s oceans, but also by ocean acidification. Under a continued rise in CO2 levels the aragonite concentrations that coral organisms require to build their carbonate reefs would be insufficient from 2070 onwards, a 2010 study estimates. By that time many types of plankton and shellfish could already be much worse affected. This is very relevant to the Cancún negotiations and the UNFCCC process. Failure to reach agreement on carbon emissions reductions would point the world to albedo geoengineering. A recent cost analysis shows a compensating cooling using sulphur aerosols could be cost-effective. Opting for this route may however undermine attempts to contain the ever increasing CO2 concentrations – thereby loosing grip on ocean acidification.

© Rolf Schuttenhelm | www.bitsofscience.org

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