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

Risk, Michael riskmj at mcmaster.ca
Sun Apr 30 11:06:22 EDT 2017

   Hello Steve.

   I would like to be optimistic, but I am not.

   This list has seen a lot of recent discussion on causes of decline. People
   have taken sides. I am not remotely surprised to see those involved in
   “managing” the reefs of the Florida Keys plump for “global change” as the
   main driver. After all, those reefs went from 45% cover to <4% under that
   mgt-and it’s always easier to blame external forces than deal with local
   stresses. But.

   We must always bear in mind that Caribbean decline started long ago: in
   60’s and before in Jamaica (Goreau, 1992: “mass bleaching did not occur
   before 1987"), and before the early 70’s in Florida (Dustan). So those
   land-based stresses are still ongoing, to which we must add warming and OA.
   But now the opposition has been handed a new weapon.

   There has been recent coverage, here and in the media, of the effects of
   oxybenzone sunscreen on corals. A campaign to ban these sunscreens was
   started on Hawaii. Legislation was proposed.

   This  should  have been a slam dunk: toxicity so high that one drop of
   oxybenzone  in 6 Olympic swimming pools shuts down coral reproduction;
   alternative (European) products available; evidence that “zombie reefs” had
   formed where sunscreen use was high. Again-but.

   American industry went into high gear defending the indefensible. Their
   major point was "climate change is the primary driver of coral death.” The
   legislation stalled.

   So for the foreseeable future, attempts to control local stresses will be
   met with the argument that the major problem lies elsewhere.

   There is almost zero chance the coral reef biological community will come
   together  in  time-they  haven’t yet, and the world has lost a lot off
   reef…besides, even if they did, they would have to convince society in
   general-and the world may shortly have bigger problems to face.

   My  first saltwater dive was Dry Rocks, 1959. It is with deep personal
   sadness that I now believe the major value of coral reefs, to society, may
   be the lesson they impart in their passing.


   On Apr 30, 2017, at 10:10 AM, Steve Mussman <[1]sealab at earthlink.net> wrote:

    Dear Mike ,
   You make a number of good points and I agree with you although I'm trying my
   best to resist accepting what I consider to be your realistic/pessimistic
   position on the future of coral reefs. It is just too painful a picture to
   envision so for now I choose to look away. Sometimes even focusing on the
   next resurgence that I like to imagine will occur over geological time. We
   certainly did miss opportunities to speak with a forceful, unified voice
   early  on,  but  I attribute that to our tendency to unify only when a
   situation rises to the level of an undeniable crisis. Coral reefs now seem
   to be approaching that tipping point so the question has the be is there
   single mindedness among coral scientists as to what must be done and can a
   message be articulated that can save the day or at least make it appear as
   if we tried?  I don't presume to have the answers, but at this point it
   appears that reducing carbon emissions holds out our best chance.  That
   doesn't mean that addressing local stressors is futile or meaningless, only
   that such efforts should be framed in such a way that there is no ambiguity
   - if we are to have any real hope of preserving what's left of our coral
   reefs we must address anthropogenic climate change. I come at this from the
   diving industry where a message has evolved suggesting that protecting
   marine  ecosystems  equates to increasing MPAs (without limiting diver
   access), removing plastic debris, controlling lionfish populations and
   protecting sharks and rays - all worthwhile endeavors, but without clear
   recognition of the overriding impacts of climate change it seems to me to be
   nothing more than a cruel facade.  It's as if a powerful line from a movie
   rules the day. "You can't handle the truth!"
   Sent from my iPad
   On Apr 27, 2017, at 12:35 PM, Risk, Michael <[2]riskmj at mcmaster.ca> wrote:


   There is certainly little to disagree with in your statement. I take an even
   more nuanced and pessimistic position-if it is indeed possible to be more
   pessimistic than “looming extinction.”

   Some years ago, I posted on this same list comments to the effect that sure,
   global warming will put an end to coral reefs: but it really will only be
   kicking over the edge of the cliff those poor sad remnants that remain after
   we humans have messed with them.

   We need to bear in mind that the world had already lost a lot of reefs,
   perhaps more than half the original total, by the time climate change began
   to ramp up. Yes, undoubtedly, we need to band together and speak with one
   voice about reducing outputs of carbon dioxide. At the same time, I wonder:
   where  was  that unanimity of purpose in the past, when the impacts of
   land-based sources of pollution were obvious? Reef biologists chased after
   various hypotheses-the reefs will come back if only the fish come back, or
   if the urchins come back, or… while ignoring the gorilla in the room.

   I do not really understand why this happened. Perhaps there was fear to
   challenge vested interests; perhaps there was money to be made consulting
   for developers and saying nutrients were unimportant; perhaps the trees of
   individual careers were pursued inside the forest of gathering decline.
   Perhaps the biologists who dominate this field were loath to tackle aspects
   of chemistry and geology involved in pollution and sedimentation studies.

   Those really interested in maintaining reefs need to bear in mind that there
   have been (to the best of my always-incomplete knowledge) only two studies
   on what happens to reefs if you improve the water quality: one Caribbean,
   one Pacific. In both cases, the reefs improved. In neither case should this
   have come as a surprise.

   In short, I agree with you that we need a unified front, and my opinion is
   that the need is all the greater because there was not a unified front 30
   years ago. We have lost the opportunity to see how well truly unstressed
   reefs respond to ocean warming. The news from the Northern GBR is truly
   appalling-but as Charles says, recovery is another story.

   I echo Charles’ sentiments, that we are conditioned by the reefs we have
   seen. To me, a trip into the future was always epitomized by the transect
   going from the outer Pulau Seribu (Thousand Islands) into the harbour at
   Jakarta. One goes from lush coral islands (though severely over-fished),
   past impoverished reefs, past some reefs that are now no more (see Tom
   Tomascik’s poignant descriptions) and finally into an azoic sea-floor out of
   the Archean. That’s what the future holds.


   On Apr 26, 2017, at 11:41 AM, Steve Mussman <[3]sealab at earthlink.net> wrote:

   Dear John and Mike,
   I ask this respectfully,  don't you both (as well as the vast majority of
   your colleagues) ultimately arrive at the same conclusion?
   Correct me if I'm wrong, but regardless of how we got here, don't you agree
   that it is ocean warming that now represents the consummate threat?   I may
   be interpreting things incorrectly, but It seems to me that at this point we
   need a unified message reflecting the urgency of addressing this particular
   At the same time we can all remain supportive of the various efforts aimed
   at addressing local stressors.

   Sent from my iPhone
   On Apr 25, 2017, at 8:50 AM, Bruno, John <[4]jbruno at unc.edu> wrote:

   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:
   [5]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
   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
   0438), 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: htt


   1. mailto:sealab at earthlink.net
   2. mailto:riskmj at mcmaster.ca
   3. mailto:sealab at earthlink.net
   4. mailto:jbruno at unc.edu
   5. http://theseamonster.net/2017/04/caribbean-bleaching/nclimate2915-f4/
   6. http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000438

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