[Coral-List] Evidence that ocean warming has caused most Caribbean coral loss

Bruno, John jbruno at unc.edu
Tue Apr 25 08:50:16 EDT 2017

Dear Mike, thank you for your ongoing interest in this topic and my post.

"the Caribbean had already lost more than half its reefs before water temperatures had increased by more than a fraction of a degree”

This is a common misconception from folks unaware that global warming began many decades ago. Please have a look at the NOAA data plotted in this figure from my post: http://theseamonster.net/2017/04/caribbean-bleaching/nclimate2915-f4/  Or the graphics in Kuffner et al 2014 below it. These data should sort you out. The Caribbean had clearly warmed significantly by the time mean coral cover had been roughly halved (around the mid-1980s). Also, we haven’t lost any reefs yet, what we’ve lost is coral cover (and fish biomass).

Iv’e dove near Havana and I agree - its a mess and was probably locally impacted. And I don’t understand the logic in arguing managers should give up because climate change has had significant impacts on corals. I’ve said it a million times: local impacts need to be mitigated. We all agree on that. I think you’re underestimating managers and local conservation capacity. (All the managers I know acknowledge climate change but aren’t giving up). As the Ocean Optimism symposium highlighted over the weekend, local successes are realistic and very much meaningful and worthwhile.

"and there is overwhelming evidence of land-based stress going back to the 70’s”

You have been promising this list-serv these references for years now. If you ever find them, please do share with us if you have the time.

"how well could coral reefs survive ocean warming if they were not already stressed by [local] human impacts?”

That experiment has been run dozens of times. On the northern GBR, on Scott Reef, off Southern Cuba or in the Bahamas, across the central Pacific, etc. The answer is not well at all.

The reason is that local impacts do not appear to act synergistically with ocean warming. As Cote and Darling suggested (http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000438), the interaction appears to be antagonistic, not synergistic. Either that or the impact of warming is so much stronger that it swamps the local and synergistic signals. Also see Darling et al 2010: http://research.fit.edu/sealevelriselibrary/documents/doc_mgr/389/Kenya_Coral_Reef_Stressors_Not_Synergistic_-_Darling_et_al.pdf



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