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

Risk, Michael riskmj at mcmaster.ca
Thu Apr 27 12:35:31 EDT 2017


   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 <[1]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 <[2]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:
   [3]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:jbruno at unc.edu
   3. http://theseamonster.net/2017/04/caribbean-bleaching/nclimate2915-f4/
   4. http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000438

More information about the Coral-List mailing list