The day has come. Scientists are heartbroken. Corals are as good as dead. RIP beautiful coral reefs. (sniff, sniff, *reaches for Kleenex*)
It must be grim; it’s not like Eric Holthaus to get all emotional and fatalistic about yet another global warming catastrophe. So, I thought I’d lend support and give him a shoulder to cry on:
Then I thought I would do some digging and see what all the fuss was about. First the paper itself:
Spatial and temporal patterns of mass bleaching of corals in the Anthropocene
Not enough time for recovery
Coral bleaching occurs when stressful conditions result in the expulsion of the algal partner from the coral. Before anthropogenic climate warming, such events were relatively rare, allowing for recovery of the reef between events. Hughes et al. looked at 100 reefs globally and found that the average interval between bleaching events is now less than half what it was before. Such narrow recovery windows do not allow for full recovery. Furthermore, warming events such as El Niño are warmer than previously, as are general ocean conditions. Such changes are likely to make it more and more difficult for reefs to recover between stressful events.
Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.
The title alone is enough to warn you that what comes after is not necessarily going to be unbiased, hard-nosed science, but ideology. The Anthropocene is an idea, not a formally recognised geological period. Its adoption is being pushed by people like Mark Maslin, for obvious reasons, not without resistance from actual geologists. Thus its use without qualification in a ‘scientific’ study should ring alarm bells.
Unfortunately, the paper is pay-walled, so I’ll have to rely upon second hand reports as to what is actually in it, but the general gist seems clear. The authors analysed 100 coral reefs between 1980-2016, looking at coral bleaching events. They concluded that not only have bleaching events become more common since 1980, they have become global in scope, whereas apparently, before then, bleaching events were localised. In the words of Prof Terry Hughes, lead author of the study:
Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise.
The articles continues:
The study establishes a transition from a period before the 1980s when bleaching only occurred locally, to an intermediate stage in the 1980s and 1990s when mass bleaching was first recorded during warmer than average El Niño conditions, and finally to the current era when climate-driven bleaching is now occurring throughout ENSO (El Niño-Southern Oscillation) cycles.
So, they took their data from the 1980s onwards and claim that before then coral bleaching events were localised only, not global. I don’t know if there was any consistent worldwide monitoring of the state of coral reefs prior to 1980, but here’s a thing. El Nino and La Nina instrumental records only go back to 1950. Guess what? There have only been three recorded “very strong” or super El Nino events since 1950 – all after 1980, namely 1982-83, 1997-98 and 2014-16 (NOAA keep messing with the 0.5C 3-monthly mean thresholds for these events, making it difficult to know when exactly they started and ended. Twice now: once when they updated to ERSSTv4, then again when they updated to ERSSTv5).
Yebbut, we should expect more super El Ninos because the oceans are warming, right? No, it doesn’t work like that. El Nino and La Nina events are defined by anomalies or departures from a 30 year mean and CPC have now adopted a system where this mean period changes every 5 years in order to account for warmer oceans, so the strength of El Ninos is intrinsic, not relative, and consistently defined throughout the record.
Which means that the authors of this study have (cherry?) picked a period in history where very strong El Ninos have been unique and frequent and by no means at all can this fact be unequivocally attributed to climate change. Indeed, it is more likely to be related to the Great Pacific Climate Shift of 1976, whose cause is still something of a mystery. Which means that the global mass bleaching events which the authors identify and which Hughes tells us were “unheard of” before 1980 might be rather more related to super El Ninos than actual generalised warming of the oceans. If so, GHG warming, even supposing it is the main contributor to the rise in tropical ocean temperatures since 1980 (very debatable) is not the principal cause of widespread coral bleaching events; El Ninos are and these events are naturally caused and have been ongoing for centuries. Oh bugger.
But wait, is it just El Nino events that cause mass coral bleaching? Apparently not . The Guardian says:
Friday’s paper also determined the link between El Niño and mass bleaching events has diminished as global warming continues.
Prior to the 1980s mass coral bleaching on a regional scale was “exceedingly rare or absent” and occurred in localised areas stretching tens of kilometres, not the hundreds of kilometres affected in recent times, the paper said.
These local bleaching events were largely caused by small-scale stressors like unusually hot or cold weather, freshwater inundation or sedimentation.
Then global warming increased the thermal stress of strong El Niño events, the paper said, widening the impact of individual bleaching events. Now, they are occurring at any time.
“Any time”? That would imply that mass coral bleaching is occurring randomly regardless of El Nino events. This is clearly double Dutch from the Guardian. The paper itself says coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases. It should come as no surprise then that there have been three mass coral bleaching events since 1980 associated with very strong El Ninos (1983, 1998 and 2016). There is also a fourth mass bleaching event associated with the “moderate” Modoki (Central Pacific) El Nino of 2010. So in that respect yes, there is evidence that even the moderate El Nino in 2010 bleached corals across the world because tropical sea surface temperatures were already elevated. You might say this was because of GHG global warming occurring since 1980. You might also say that it was due to an enhanced release of ocean heat via two very strong El Ninos in 1982-83 and 1997-98. Where did that ‘extra heat’ come from though? Climate scientists will tell you it was prevented from escaping from the planet by demonic CO2. Others might tell you it arose via enhanced direct solar short wave heating of the tropics due to the decrease in tropical cloud cover that occurred from the early 1980s to 2000, remaining stable thereafter.
Who knows for sure. Climate scientists just think they know. Climate change activists and warmist politicians don’t think, but they know. What is certain is that the huge El Nino of 2014-16 resulted in yet another major global coral bleaching event in 2016. Warmists freaked out and still are freaking out. The Great Barrier Reef was reportedly dead, then it started to recover, but alas, warmists have not recovered their senses and now tell us that coral everywhere will never recover – ever (unless of course we – but not the Chinese or the Indians – decarbonise yesterday).
I’m not sure how the authors did their analysis, not being privy to the paper itself, but here’s what the Guardian says about the increase in frequency of mass bleaching events:
The study found that time between bleaching events had diminished five-fold in the past 30 to 40 years, and was now too short to allow for a full recovery and was approaching unsustainable levels.
While mass bleaching events used to occur about once every 27 years, by 2016 the median time between them had shrunk to 5.9 years. Only six of the 100 sites had escaped bleaching.
Just like the shrinking Arctic sea-ice measured over 36 years which was supposed to be the death knell for polar bears, corals are now deemed to be in imminent danger of extinction using 36 years of coral bleaching observations and only 4 recorded instances of mass bleaching – in 1983, 1998, 2010 and 2016. Yes, the time between events has shortened dramatically – but they only have 4 data points to work with! However, this appears to be sufficient to pronounce gravely upon the future survivability of corals in the dreaded Anthropocene, i.e. corals which survived the extinction of the dinosaurs, which survived the rapid 4C global warming of the PETM, which have survived millions of years on a hotter Earth when no ice existed at either pole, are done for because the planet warmed 0.6C after 1980 and we had a few very powerful El Ninos which bleached them.