Guest essay by Jim Steele
Director emeritus Sierra Nevada Field Campus, San Francisco State University and author of Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism
A Warm Evolutionary Legacy
Despite increasing confirmation of the Adaptive Bleaching Hypothesis and its ability to explain coral resilience, most people are unaware of its debate within the scientific community. The ability to rapidly adjust to changing environments by modifying their symbiotic partnerships has been the key to their success for millions of years. As one expert wrote, the “flexibility in coral–algal symbiosis is likely to be a principal factor underlying the evolutionary success of these organisms”.
Our modern day reef-building corals first evolved in exceedingly warm and stable climates when deep ocean temperatures were 10°C higher than today and palm trees dotted the Antarctic coast. As ice caps began to form in Antarctica ~35 million years ago sea levels fell and warm epi‑continental seas dried. After ocean depths had cooled for another 30 million years, Arctic ice caps began to form and the earth entered an age with multiple episodes of glacier advances and retreats causing sea levels to rise and fall. Just eighteen thousand years ago during the last glacial maximum, all our shallow reefs did not exist, as sea levels were 400 feet lower than today.
The 35 million year cooling trend increasingly restricted reef-building corals to more tropical latitudes where winter water temperatures remain above 16 to 18 °C. As their evolutionary history would predict, today’s greatest concentrations and greatest diversity of corals are found in the earth’s persistently warmer waters, like the Indo-Pacific Warm Pool. Likewise species inhabiting our warmest waters have undergone the fewest episodes of severe coral bleaching. Given their evolutionary history, coral’s greatest achievement has been enduring bouts of sustained climate cooling and rapid temperature swings. Even during warm interglacials coral battled cold temperatures dips. Studies of 7000-year-old fossil coral reefs in the South China Sea revealed high coral mortality every 50 years due to winter cooling events. Indeed most researchers believe past coral extinctions were most commonly due to cold events. Accordingly research has estimated that during the cold nadir of each ice age, coral reef extent was reduced by 80% and carbonate production was reduced by 73% relative to today.
As the last ice age ended, coral expanded their range with warming temperatures. At the peak of the Holocene Optimum 10,000 years BP (Before Present), coral adapted to tropical ocean temperatures in the heart of the Coral Triangle were 2.1 °C warmer than today. As illustrated above, temperatures cooled since then but frequently spiked or plummeted by 2 to 3 degrees over the course of a few centuries. One thousand years ago during the Medieval Warm Period, coral thrived in Pacific water masses that were ~0.65° warmer than in recent decades, then cooled ~0.9°C by the 1700s. Given coral’s evolutionary history, it is unlikely coral were better adapted to 1800s Little Ice Age temperatures versus Medieval Warm Period or 20th century temperatures. Emerging research now suggests coral bleaching has been an integral part of corals’ adjustment mechanisms to an ever-changing environment.
Coral Mortality and Resilience
There are 4 widespread misconceptions about bleaching propagated by tabloid media hyping climate doom and researchers like Hoegh-Guldberg. To clarify:
1 Bleaching is not always driven by warming temperatures
2 Bleaching is not responsible for most coral mortality.
3 Coral can rapidly respond to disturbances and replace lost cover within a decade or less.
4 Bleaching, whether or not it results in coral mortality, is part of a natural selection process from which better-adapted populations emerge.
1. Multiple Causes of Bleaching
In contrast to researchers like Hoegh-Guldberg who emphasizes coral bleaching as a deadly product of global warming, bleaching is a visible stage in a complex set of acclimation mechanisms during which coral expel, shift and shuffle their symbionts, seeking the most beneficial partnership possible. Bleaching can be induced by stressful interactions between temperatures, disease, heavy rains, high irradiance from clear skies and competition with seaweeds. Indeed abrupt warm water events like El Nino have induced widespread bleaching and high mortality. But cold winters or La Nina induced upwelling of colder waters have also induced bleaching.
NOAA has also contributed to these misconceptions by overemphasizing just warm-event bleaching. On NOAA‘s web page “What is Coral Bleaching”, NOAA reported, “the U.S. lost half of its coral reefs in the Caribbean” in one year due to warmer waters. But the Caribbean’s main cause of lost reefs was due to an outbreak of the White Band disease in 1981-82. White band specifically targets members of the genus Acropora, like the Staghorn and Elkhorn coral, reducing by 80% of their cover that once dominated the Caribbean reefs. However since the mid 80s experts reported coral cover has changed relatively little.
NOAA also downplayed cold temperature bleaching stating the 2010 cold event just “resulted in some coral death.” However NOAA’s statement stands in stark contrast to coral experts who reported the January 2010 cold snap was the worst coral bleaching and mortality event on record for Florida’s Reef Tract. They reported, “the mean percent coral mortality recorded for all species and subregions was 11.5% in the 2010 winter, compared to 0.5% recorded in the previous five summers, including years like 2005 where warm-water bleaching was prevalent.” Globally there has been an increase in observed cold bleaching events and 2010 was Florida’s first cold bleaching since the 1970s. Globally there have been several more reports of cold induced bleaching and then recovery as the waters warmed.
There is a perception that bleaching suddenly became more common only since the 1980s, leading some to speculate bleaching is due to rising CO2 and global warming. However, whether warming since the Little Ice Age is natural or anthropogenic, warming does not explain the increased observations of cold bleaching. More frequent observations of bleaching events may be partially due to the advent of remote sensing satellites that have allowed greater global coverage only since the 1980s. Furthermore determination of bleaching severity and mortality requires teams of divers to ground truth satellite data and fine-tune percentages of affected reefs. But SCUBA diving only became possible in the decades after Jacques Cousteau invented the Aqualung in the 1940s. Although natural rates of warming during the 30s and 40s were similar to today, coral reef studies were also hampered by the unsafe battleground between Japan and the Allies. War-time efforts such as the Battle of the Coral Sea, and fights to control the islands of Peleliu, Midway, Iwo Jima, the Philippines, or subsequent nuclear testing on the Bikini Atoll. The resulting reef devastation likely obscured any natural bleaching events.
We now know bleaching regularly happens due to seasonal fluctuations between high solar irradiance and warm temperatures of summer versus lower irradiance and cooler temperatures in winter. High irradiance can damage the corals’ symbiotic algae when photosynthesis runs too rapidly, while low irradiance detrimentally reduces photosynthetic output. Thus coral undergo natural adjustments to seasonal changes by expelling a portion of their symbiotic algae in summer. This leads to temporary or partial bleaching. Low light and colder temperatures slow photosynthesis, so coral increase their symbiont density in winter.
Similarly in response to changes in sunlight, the same species will alter their symbiotic partnerships as irradiance declines at increasing depths or when and where water turbidity alters irradiance. Bleaching is often temporary and mild as coral shuffle and switch their symbiotic algae in order to adapt, but sustained extremes, warm or cold, can prolong bleaching and starve the coral. Whether coral die or not depends on how quickly new symbionts are acquired relative to how much energy the coral has stored, or coral’s ability to feed on plankton as an alternative energy source.
All recent global bleaching events have been driven by El Nino events. The 1998 El Nino caused widespread mortality, an estimated 16% globally. Observed bleaching in response to warm tropical waters invading cooler regions aroused fears that climate change had contributed to this “unprecedented” event. However researchers have noted the relationship between warmer ocean temperatures and “bleaching has been equivocal and sometimes negative when the coolest regions were not in the analyses.” In other words coral living in the warmest waters were well acclimated to the warmest waters redistributed by an El Nino. Furthermore mortality did not always occur during periods with the warmest temperatures, but during the winter or ensuing cold La Nina conditions. Such observations suggest the rapid swings between anomalously warm El Nino and anomalously cold La Nina conditions are the most stressful.
Stressful rapid temperature variations due to El Nino events have occurred throughout the past 10,000 years. As illustrated below from Zhang 2014, the frequency of El Ninos during the past century has been neither extremely high, nor extremely low. Most living coral species have survived over a million years of climate change and have endured the extreme El Nino frequencies of the past 3000 years including the Little Ice Age. El Nino events are a function of natural ocean variability and there is no consensus regards any effect from rising CO2 on El Nino frequency or intensity. To survive extremes from past natural variability, coral species had to be extremely resilient in ways that are just now being understood.
2. Bleaching Causes the Least Mortality
Most extreme bleaching events are associated with El Ninos, but the high mortality rates are not just a function of higher temperatures. Due to associated flooding and high rainfall, the resulting change in salinity disrupts coral osmosis, which can result in coral death. Furthermore tropical storms and heavy wave action are a major cause of lost coral reefs, but storms also bring heavy rains that also induce bleaching. Although some try to link storm-related mortality to climate change, there is no evidence of an increasing trend in tropical storms. As illustrated by the pie graph from Osborne 2011, in the Great Barrier Reef the explosion of the coral-eating Crown of Thorns starfish (A. planci) and tropical storms contributed to the greatest loss of coral colonies, 70.5%. Bleaching is a very minor contributor to coral mortality, just 5.6%, and that bleaching can be induced by warm or cold temperatures, heavy rains and floods or high irradiance from anomalously clear skies.
Due to coral’s symbiotic efficiency and recycling of nutrients, corals dominate in nutrient-limited tropical waters. Normally those low nutrient conditions also prevent predators like the Crown of Thorns starfish (COTS) from rapidly reproducing because their plankton-feeding larvae typically starve. But increased inflow of nutrients due to landscape changes, agriculture run-off and sewage, has increased plankton blooms and thus the survivorship of COTS’ larvae. The ensuing population explosions of coral eating adults have decimated many reefs. COTS does not exist in the Caribbean. Instead coral there are battling bacterial diseases like white-band that can be spread by coral-eating snails. Humans have indeed tipped the balance in favor of COTS and in addition to destructive over fishing with dynamite and cyanide, those causes of coral death are the only factors we can remedy.
To understand coral resilience in the face of the variety of onslaughts, coral reefs must be seen as dynamic systems that oscillate over decadal periods, as well as centuries and millennia. Snapshots focused only on a few years when coral reefs decline misrepresents coral resilience and promotes false gloom and doom, as well as useless management plans. A long-term study of coral ecosystems of an island in French Polynesia demonstrates corals’ dynamics response to 32-years of storms, Crown of Thorns starfish and bleaching. Coral mortality is often measured as a function of the change in “coral cover”, and 45 to 50% of the healthy reef system around the island of Tiahura was covered with coral.
As illustrated below in Figure 1 from Lamy 2016, an outbreak of COTS removed 80% of the live coral cover between 1979 and 1982, reducing total coral cover to 10% of the reef. However by 1991 the coral had fully recovered. As designated by the small gray arrows at the top, three bleaching events occurred during that recovery period. Later destruction from a 1991 cyclone again reduced coral cover but again coral recovered reaching its greatest coverage of 50% by the year 2000. And again during that recovery there were 3 more bleaching events. Since 2006 the coral suffered their greatest loss due to another outbreak of COTS, quickly followed by another cyclone. High mortality promoted high seaweed cover (dotted green line) that has inhibited coral recovery. Over that time, coral bleaching was associated with periods of recovery, suggesting little if any detrimental effects. As will become clear shortly, one also could reasonably argue those bleaching events were beneficial.
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3. Rapid Coral Recovery:
Tiahura’s coral recovery periods typically required 7 to ten years, and appeared to be unaffected by the 1998 El Nino. Several other studies have reported similar recovery periods, but some locations required 10 to 20 years to fully recover. In Australia’s Great Barrier Reef (GBF), the 1998 El Nino induced above average sea surface temperatures and salinity changes for 2 months triggering massive coral losses in the reef’s upper 20 meters. At the GBF’s Scott Reef, the upper 3 meters lost 80 to 90% of its living coral and the disappearance of half of the coral genera. Yet researchers observed, “within 12 years coral cover, recruitment, generic diversity, and community structure were again similar to the pre-bleaching years.” A similar long-term study in the Maldives observed a dramatic loss of coral during the 1998 El Nino but by 2013 the reefs also had returned to “pre-bleaching values”. Although a reef’s recovery sometime requires re-colonization by larvae from other reefs, a process known as re-sheeting or Phoenix effect can facilitate a reef’s speedy recovery. Often a small percentage of living “cryptic” polyps with a more resilient symbiotic partnership were embedded within a “dead” colony and survive extreme bleaching. They then multiply and rapidly “re-sheet” the colony’s skeletal remains.
In addition to rapid recovery of coral cover, researchers are finding bleached reefs have been increasingly less susceptible to subsequent bleaching. For example studies in Indonesian waters determined that two coral species, highly susceptible to bleaching, had experienced 94% and 87% colony deaths during the 1998 El Nino. Yet those same species were among the least susceptible to bleaching in the 2010 El Nino, with only 5% and 12% colony deaths despite a similar increase in water temperatures. Similarly, changes in resilience were observed in response to cold water bleaching in the Gulf of California. Increased resilience in response to a variety of bleaching events prompted the Adaptive Bleaching Hypothesis first proposed in 1993. The hypothesis suggests that although bleaching events are a response to stress, it creates the potential for coral to acquire totally new and different symbionts that are better suited to those stressful conditions. Contrary to Hoegh-Guldberg’s claim that coral reef systems will “experience near annual bleaching events that exceed the extent of the 1998 bleaching event by the year 2040”, scientists are increasingly observing the exact opposite. After reefs recover from severe bleaching, colonies have evolved enhanced resilience to future bleaching.
4. Coral Symbiosis, Symbiont Shuffling and Rapid Adaptation
A single coral colony is comprised of 100s to millions of individual “polyps” (seen above). Each polyp can be visualized as an upside down jellyfish (coral’s close cousins) with their backs cemented to a surface and tentacles extended outward to capture passing food particles, live prey, or new symbionts. However because coral live in nutrient depleted environments, in addition to filter feeding, polyps harbor single-celled photosynthesizing symbionts inside their cells. Those symbionts (aka zooxanthellae) typically provide ~90% of the coral’s energy needs. Just 40 years ago it was believed all corals were host to just one photosynthesizing symbiont, a single species from the dinoflagellate genus Symbiodinium. But thanks to technological advances in genetic sequencing, we now know a coral species can harbor several potential species or types of Symbiodinium algae, each capable of responding optimally to a different set of environmental conditions and coral physiology. As predicted by the adaptive bleaching hypothesis, improved genetic techniques have revealed a wondrously diverse community of symbionts that coral can choose from. Coral can no longer be viewed as organisms that only adapt slowly over evolutionary millennia via genetic mutation and natural selection. Coral must be seen as an “eco-species” (aka holobiont) that emerges from the synergy of the coral and its varied symbionts. And we now know those emergent eco-species can rapidly evolve with changing climates by shuffling and shifting those symbionts.
A single colony’s polyps are typically all clones resulting from asexual reproduction and on their own offer the colony scant genetic versatility. However within a colony, a wide variety of symbionts can be harbored within a small percentage of polyps, although one symbiont type typically dominates. That small percentage of “cryptic” polyps often survive severe bleaching episodes and then multiply rapidly over the skeletal remains in a process known as the Phoenix effect. Just one square centimeter of coral tissue typically harbors a million individual symbionts and on average those symbionts can double every 7 days. Thus after severe colony bleaching, a more resilient colony can arise in just a few years with better-adapted symbionts now dominating. Likewise symbiont variability within a reef results in some colonies bleaching while adjacent colonies of the same species do not. And similarly a varied symbiont and coral community allows neighboring reefs to adapt to their unique regional climates.
Figure 6 Colony on the left remains unbleached
Variations in coral reproduction can conserve an “ecospecies” or rapidly promote greater ecospecies diversity. Twenty-five percent of the coral species produce larvae inoculated directly from their parent’s symbionts. However 75% of the species produce larvae that initially lack a symbiont. Only after coral larvae settle on a surface, do those larvae engulf one or more different types of free-living Symbiodinium, drawing them inside their cells. As the larvae develop into mature polyps, coral typically keep the symbiont types best suited to the local microclimate and expel the others. In this manner completely new eco-species emerge.
Furthermore as conditions change, all species can shuffle their symbionts as polyps will expel their current residents and acquire a different type that had been harbored by a neighboring polyp. A colony can also shift its symbiont population by acquiring new types not yet hosted by the colony but are present in the reef. Due to improving genetic techniques, previously undetected types of symbionts with greater thermal tolerance are now being detected after bleaching events. Thus a combination of symbiont shuffling and shifting is the key to corals’ rapid adaptation. Although bleaching can result in coral death due to starvation when new symbionts are not acquired quickly enough, surviving polyps with their altered symbiont community have the potential to re-direct the reef on a trajectory that is better suited to the new environment. Or if conditions return to those prior to an extreme event, coral can re-acquire their old symbiont types.
Scientists have found that coral colonies nearer the surface often harbor a different type of symbiont than colonies living just a few meters deeper. The symbionts residing closer to the surface may be better adapted to high irradiance by making proteins that protect against too much ultra violet light or by modifying their photosystem. Conversely symbionts living at greater depths may photosynthesize more efficiently under low light conditions but are more susceptible to UV damage. Transplant experiments revealed that when coral colonies growing at greater depths were relocated closer to the surface, the polyps expelled their symbionts resulting in temporary bleaching. Bleaching allowed polyps to acquire new symbionts better adapted to higher irradiance. However colonies adapted to high-light surface conditions, photosynthesized much more slowly when transplanted to lower depths. Bleaching never happened and the coral died. Although experiments can force bleaching by raising temperatures, other controlled laboratory experiments found that in the absence of stress from high solar irradiance, anomalous temperatures 4 degrees above average still did not induce bleaching.
According to the adaptive bleaching hypothesis we can infer that bleaching events are not simply the result of recent global warming. Bleaching should have been ongoing for millions of years, as background temperatures have risen and fell. Thus we would expect that as the Little Ice Age ended and naturally temperatures rose, there should be observations of bleaching in the early 1900s. And indeed there are albeit limited. For example bleaching was reported in Florida on hot days in the early 1900s. But more telling, enough warm weather bleaching had been observed in the early 20th century that the Great Barrier Reef expedition of 1928-29 focused on warm weather coral bleaching when oceans were cooler than today and long before any possible CO2 warming effect.
Coral Response to Climate Change
Since his first Greenpeace-funded 1999 study, Hoegh-Guldberg has promoted catastrophic climate change as the biggest threat to coral reefs. His papers are frequently cited as evidence of climate related coral demise by some researchers and hyped by media outlets that boost readership by promoting climate catastrophes. The bases for his claims relied on 3 simplistic assumptions that a) bleaching is evidence that coral have reached their limit of maximum thermal tolerance, b) bleaching will increase due to global warming, and c) coral cannot adapt quickly enough to temperatures projected by climate models.
In 1999 Hoegh-Guldberg argued “thermal tolerances of reef-building corals will be exceeded within the next few decades” and coral reefs “could be eliminated from most areas by 2100” due to climate change. In his 2014 paper he continued to dismiss the emerging science supporting the adaptive bleaching hypothesis, belittling it as a “persistent mirage”. His catastrophic claims also intensified, suggesting “as much as 95% [of the world’s coral] may be in danger of being lost by mid-century.” To support his extirpation claim he cited two of his own previously published papers. Hoegh-Guldberg’s history of exaggeration and circular reasoning has led other coral experts to accuse him of “popularizing worst case scenarios”, while others have accused him of persistently misunderstanding and misrepresenting the adaptive bleaching hypothesis. Furthermore other researchers have pointed out the pitfalls and weaknesses in framing threats to coral based on a simplistic temperature threshold. They argue, “A view of coral reef ecosystems that emphasizes regional and historical variability and acclimation/adaptation to various environments is likely to be more accurate than one that sees them as characterized by stable and benign temperature regimes close to their upper thresholds.”
As one of many examples of his deceptive misstatements, in his 2014 paper Hoegh-Guldberg wrote, “there is little evidence that acclimatisation has resulted in a shift or extension of the upper thermal tolerance of reef-building corals [42].” His citation simply referenced a paper he had co-authored. But in that paper he admitted never identifying the symbionts or trying to detect any symbiont shuffling or shifting. Furthermore his methodology removed coral from their potential symbiont community during experimental heat stress treatments, minimizing any possibility for the coral to switch symbionts. But it is symbiont shifting that allows coral to shift their upper thermal tolerance levels. Hoegh-Guldberg’s basis for claiming “little evidence” was totally irrelevant, if not dishonest.
In contrast, improved genetic sequencing is increasingly providing evidence that in response to warm water bleaching events coral begin acquiring new heat resistant symbionts. The results below from Boulotte 2016 show that over the course of 2 years, colonies radically altered their symbionts. The pie charts represent the changing percentage of dominant symbiont types due to shuffling in a single reef species. The bar graphs list just the rarer symbionts and stars identify types not previously detected suggesting an ongoing shift. Symbionts “types” are characterized first by their genetic lineages known as clades. When the adaptive bleaching hypothesis was first proposed, only 4 clades were known. Now at least nine have been identified. The most heat resistant symbionts belong to clade D, but other heat resistant types have evolved within other clades. Many earlier acclimation studies simply identified a symbiont’s clade. But we now know each clade can harbor hundreds of types (potential species) and improved detection of those species is uncovering more shifting. The most heat resistant species identified to date belonged to clade C. As seen here, different types/species are identified as D_I:6 or D1.12. As illustrated below after 2 bleaching episodes, a new symbiont species from clade C began to dominate and previously undetected clade D symbionts began to appear more frequently in just 2 years.
Nevertheless Hoegh-Guldberg 2014 continues to dismiss coral’s ability to rapidly adapt arguing, “current rates of change are unprecedented in the past 65 Ma [million years] if not 300 Ma.” But such exaggeration is pure nonsense. Ocean temperatures were warmer just 1000 years ago, and paleo-studies of temperatures in the Great Barrier Reef suggest local reef temperatures were higher between 1720 and 1820 as illustrated below from Hendy 2003. (Their luminescence index measures changes in salinity associated with monsoons). Perhaps CO2 concentrations are higher now than over the last 300 Ma. But given the extreme warmth just 65 million years ago, that is evidence that our climate is not very sensitive to CO2 concentrations, as realized by more researchers. In contrast to IPCC models that predict more warming that Hoegh-Guldberg ties to coral demise, climate experts note the Holocene temperature conundrum. While CO2 driven models simulate 6000 years of warming due to rising CO2, all the proxies indicate a cooling trend interrupted only by warming spikes.
Although coral genomes may evolve slowly, their symbionts have extremely fast generation times, averaging every 7 days. Furthermore the symbiont community consists of hundreds of symbionts that have already adapted to a wide variety of temperature, irradiance and salinity variables within different microclimates over the past million years. Symbiont shuffling and shifting is an evolutionary masterpiece that circumvents plodding evolutionary mechanisms of most organisms with long generation times and enables immediate adaptation. To counter the emerging science, Hoegh-Guldberg can only invoke silly semantics to argue symbiont shifting is not “true adaptation”. But again his arguments evoke criticism from his colleagues who wrote, “flexibility in coral–algal symbiosis is likely to be a principal factor underlying the evolutionary success of these organisms”. But Hoegh-Guldberg seems less interested in embracing the emerging science of coral resilience, in order to cling to his belief in catastrophic climate change.
Jim, this is the best article on this subject I have ever seen!….
…Thank you!
I’ll give that a resounding second!
I will third. Absolutely brilliant.
Thanks Latitude. Good to have my efforts appreciated. I have always been amazed of the lack of media attention for all the research demonstrating coral resilience from symbiont shuffling and shifting. Inevitably all the gloom and doom articles that get a lot of hype simply cite Hoegh-Guldberg’s empty, one-sided assertions
Jim, this is so well written….I just can’t brag enough!
Every time I would think of something…..you would cover it in the next sentence or next paragraph.
….well written!
Swapping dinos is what they do….
If you want to have some fun….look how much hotter the Red Sea reefs are….as compared to the GBR and Caribbean…..it’s all in the dinos
My compliments as well. So nice to have such a complete, clear and concise summary of these issues.
Thank you.
What seems to have really gone extinct are many forms of curiosity. Fear and conflict are powerful in moving people to seek certainty and a global framework to explain everything.
I appreciate everything you write, but this is GREAT! I was “hoping” just the other day, that you would take up this subject.. Thank you so much!
Beautiful eloquent and succinct 🙂
Together with scorpions and cockroaches, corals are the most stubborn organisms on Earth. Just think about the deep-water (or cold-water) corals in the Noth Atlantic ocean, even growing prolifically north of the Polar Circle (www.lophelia.org). They don’t have algal symbionts, so we are looking for other symbionts, perhaps of bacterial or archeal nature. They survived the 120 m lower water level during the glaciation 18 thousand years ago, and are still thriving. To find out what they can tolerate, we have tried burying them in sediments for several days. It was found they they manage to cope even this, by retracting the polyps into their exosceletons.
Agreed!
I’ll give it a fourth, outstanding!
“It aint’t that simple” seems to be a generally true statement, and a retort to most disaster scenarios.
Coral resilience to bleaching and water temperature has always been and always will till the Sun goes dim.
Now suntan lotion is anther thing entirely, they should wear Top Rash Guardthin nylon wetsuits, I use something similar for all my tropical snorkeling and diving.
Good ol Darwin,survival of the fittest seems to be a resilient and robust hypothesis.
I’m not sure that corals experience bleaching due to abnormally warm waters at all. Is it not more likely that the phenom that CAUSES the abnormally warm water in the first place — slower overturning water currents which also decreases nutrients in surface waters — is the reason corals sometimes show bleaching in warmer surface waters?
pretty much…..think these guys are hot?
http://www.danintranet.org/storymedia/13641.jpg
RW, Experimentally warmer waters have been able to induce bleaching. Warming induced bleaching is always relative to local background temperatures. So yes an El Nino, or other changes in ocean circulation, or a high pressure system can warm the water and induce bleaching. It need not be due to climate warming such as we experienced after the LIttle Ice Age.
The habitat for coral is naturally low in nutrients, which is why their symbiotic associations are so critical. More nutrients are a mixed bag, Too much nutrients promote Crown of Stars population growth, too little can reduce plankton that coral could feed on during symbiont switching.
Warming induced bleaching is always relative to local background temperatures.
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Depends on which dino they are hosting at the time….and the concentration of dinos.
Some dinos are adjusted to the swings….corals grow in the mouths of inlets, etc where they can have massive swings in temp, pH, and salinity…..four times a day….that’s the dino they are hosting
…but if they are hosting a dino that took advantage of certain conditions….that were within it’s range…and it became dominate…and those conditions change to where it’s hostile…..then they need to go shopping for a new one
This is excellent, Thank you! I figure to post a portion of this over where I post my climate arguments, with a link back here and to your blog. (more) People need to know!
Thanks ClimateOtter, I hope many others re-post this article. Once people understand the biology the better they can evaluate the issues and separate the gloom and doom hype.
Jim, very comprehensive article. I get the GBRMPA updates and the video message starts well but always ends in a CO2 warning, always. Example from 6th May https://www.youtube.com/watch?v=aYIZfoh5Sy4
I will try to get more traction for this excellent summary on twitter.
Having observed coral bleaching over the last 30 years as a diver, I have always been convinced that temperature is not the main driver for this. It is generally the corals in the lagoons ( and thus the warmest) that seem to recover first from bleaching events. There are often areas of bleaching in cold up-wellings when the warmer surface corals remain fine. This is an excellent article that exposes the push to link the bleaching to temperature rather than to the more complex combination that I, for one, am convinced causes it. Thank you Jim Steele.
The dinoflagellates they need will not only be adjusted to the lagoon…but they will be in a much higher concentration….making it easier for them to be replaced.
But temperature alone does not explain those same corals at the mouth or inlet to that lagoon…when they can have massive swings in temp pH and salinity…four times a day or more
They have also picked up a dino clade that’s adjusted to it…..
I imagine that as science better understands the various sorts of dinoflagellates it will turn out some depend on bleaching events, in the same manner some species of pines depend on forest fires. If bleaching events did not occur, these dinoflagellates would lose their evolutionary advantage.
In New England there is a tree, the poplar, that can’t really survive unless a clearing is created, and it prefers the clearings created by beaver ponds. Once the beavers have eaten every tree in sight they abandon the ponds, the dam breaks, and a “beaver meadow” appears, and is quickly colonized by poplar trees. Poplar trees grow swiftly and have a short life span, but other trees seldom move in to shade them out, because the poplar happens to be a favorite food of beavers, who move back in, rebuild their dams, and the cycle continues.
In the view of the short-sighted the beavers running out of food is a “disaster”, the breaking of the dam and the loss of fish habitat is a “disaster”, the loss of a beaver meadow to invasive poplar trees is a “disaster”, and the return of the beavers and the destruction of a grove of poplar is a “disaster”. The short-sighted suffer many sleepless nights, for life is just one disaster after another to them.
It takes a more far-sighted view to understand there is a cycle involved, and nature has adopted species to take advantage of the cycle, and has species that fit in every phase of the cycle. I fully expect the tale of coral bleaching, and how various dinoflagellates interact with coral, will just be one more example.
A late comment just for informational extension
@Caleb 6:23 (… will know this, but others may not)
The Poplar tree reappears quickly because it does not need to start from a seed. Beavers remove only the top. See:
https://en.wikipedia.org/wiki/Populus_tremuloides#Ecology
Thanks greytide. Indeed shallow lagoons are exposed to the greatest temperature fluctuations from hot to cold as well as being most susceptible to land runoff and circulation stagnation. Shallow lagoons also expose their coral to the air during low tide as seen in Latitude’s photo above. Accordingly from the research that I have read to date, those lagoons also harbor the greatest diversity of symbionts.
Jim, that’s the great barrier reef…..
Latitude I am not sure the purpose of your comment. The Great Barrier Reef has many micro climates. The GBF has many Inshore and lagoonal reefs that are exposed at low tide. Are you saying the exposed reefs in you photo are more seaward?
I have, unfortunately, not had the pleasure of the GBR. Most of my diving has been Red sea & Indian Ocean. I am not sure that, in a high current environment as are many of the areas and lagoons of the Maldives, the dinoflagellates can be “Adjusted”. Land runoff and circulation stagnation cannot be an issue as there is nothing to run off from other than coral sands (no farming, vehicles, roads etc) and the circulation certainly does not stagnate. Maybe the warmer environment encourages a more rapid population bloom of appropriate dinoflagellates to the detriment of those not so well adapted thus providing the right organisms at the right time. Corals have survived for millennia, I’m sure that humankind will not be their downfall.
yep….that’s not in a lagoon….that’s the actual reef at a extremely low tide….happens about twice a year
http://static.panoramio.com/photos/large/67545339.jpg
correction…..It “can” happen twice a year…..doesn’t always
Who’d a thunk it.
Organisms that live in a constantly changing environment have developed the ability to handle constantly changing environments.
Will wonders never cease?
Indeed. 🙂
“But Hoegh-Guldberg seems less interested in embracing the emerging science of coral resilience, in order to cling to his belief in catastrophic climate change.” And the grants it brings from the LIP’s (low info politicians). There. Fixed that fer ya 🙂
However,as said above by many,excellent article on a long ignored/not reported species. Too bad you didn’t have more time to devote to this research.
It’s even less alarming than that.
The corals replace their clades on the fly. Bleaching is the first step where the lower temperature zooxanthellae are booted out and a higher temperature clade is brought in.
How the reef became blue again
Ray Berkelmans from AIMS, which is right on the reef at Townsville, is Ove’s rival. Ove is based ‘way south at UQ in Brisbane, which is also the employer of John Cook.
Of course the media like if-it-bleeds-it-leads stories so they publish every spouting from Prof Hoegh-Guldberg while rarely mentioning things like Dr Berkelmans’ findings.
exactly……and each “coral” being made up of hundreds of individual animals……each one can host a different zoox/dino
Here’s a porites that was obviously bi-polar……
http://cdn.phys.org/newman/csz/news/800/2016/2-scientistsbl.jpg
That looks like a pathogen, when zooxanthellae exit the skeleton it lightens almost uniformly. I laugh at these self aggrandised coral experts who can’t grow coral artificially, let alone propagate it in natural captive surroundings … when they can grow and sustain it for many years then can they pass an opinion, otherwise they have no idea. According to one such “expert” from JCU in Australia, the sign of bleaching is colorful brightness of the coral. In that case my age old stands of acropora sp have been bleaching continuously for many years at 26C water temperature and remaining colorfully bright!
Thank you, Jim. This is the most enjoyable article on living things I’ve read in a very long time.
Thanks, Jim, for a very informative post. But there is one logic error: In response to H-G’s claim that “current rates of change are unprecedented in the past 65 Ma [million years] if not 300 Ma“, you say “Ocean temperatures were warmer just 1000 years ago, and paleo-studies of temperatures in the Great Barrier Reef suggest local reef temperatures were higher between 1720 and 1820“. H-G’s claim refers to rates of change, which is not addressed by your statement on past temperatures. It seems very unlikely that H-G has any evidence that high rates of change did not occur in the past, and thus his claim would appear to be false. But in order to fully refute H-G’s claim, evidence of past high rates of change is needed.
But in order to fully refute H-G’s claim, evidence of past high rates of change is needed.
============
8000 years ago there is plenty of evidence of rates of change far in excess of present conditions. As H-G would have us believe, coral evidently went extinct at that time.
http://www.ncdc.noaa.gov/paleo/ctl/images/8200.gif
Absolutely brilliant post. Bleaching is a symbiont exchange event, evolved over millions of years to help corals adapt. Not an extinction event as warmunists falsely portray.
There is one exception. Bleaching caused by runoff organic matter decomposition producing H2S can be very deadly. LD50 for most bottom dwelling marine organisms including corals, shrimp, crabs is ~25ppb! even for most adapted mussels is only 125ppm. Essays Shell Games and When Good News Isn’t.
The reefs are okay, and always grow back. Settle…. alamists… settle.
Thank you Jim Steele. It turns out that the bleached coral disaster is another over-hyped simplification of a complex issue based on deliberately selected data with interpretation skewed towards pre-determined conclusions. In other words, typical Climate Science. Why am I not surprised?
This is the kind of well written article that allows us to come away with the feeling that we’ve learned something of substance, that the truth is much more complicated than we’ve all been led to believe, and that it isn’t nearly as bad as the media want to make out. Why am I not surprised? (except by the quality of the article which is outstanding, even by the standards of WUWT)
Plus many. The quality here is outstanding.
The world needs more Jim Steele’s
Many thanks for the VERY informative piece on corals. I had never thought of corals as a life form in a low nutrient environment and the evolutionary challenges which result. INTERESTING!
Valerie Taylor [ http://www.telegraph.co.uk/culture/film/11700946/The-most-glamorous-shark-hunter-in-the-world.html ] saw widespread bleaching along the GBR in the mid 1960s [ http://www.theaustralian.com.au/life/weekend-australian-magazine/valerie-taylor-80-diver-and-shark-expert/news-story/a2c552677cbe0ff0f09f8ed282fbfd12 ].
By the mid 1970s all traces of the bleaching had gone.
That suggests reefs are a bit more resilient than the chicken littles would have us believe.
but but but … they wouldn’t be able to fleece the public with apocalyptic stories of the death and destruction of the GBR.
Enjoyed reading this immensely. Gives me a lot of material to track down and study. Thanks!
See also the reefs – both shallow and deep in the muddy waters of the Amazon River delta.
http://www.cbc.ca/news/technology/coral-reef-amazon-1.3559343
It is very interesting from an evolutionary point of view. Those polyps that bleach have a very high chance of dying, but if they do die they open the way for the coral to be recolonized by their “cryptic” clonal polyps that survive because they have better adapted symbionts. Their dying increases the chances of colony survival.
Let’s hope Dr. Hoegh-Guldberg doesn’t find out about the mass die-off of timber bamboos every so often. He would probably attribute that to global warming, too.
4 Bleaching, whether or not it results in coral mortality, is part of a natural selection process from which better-adapted populations emerge.
Similarly the reason that we hunted the Passenger Pigeon to extinction was to produce better pigeons.
I guess the passenger wasn’t one of the better ones.
….
Reefs are suffering from pollution, from ocean acidification, from warming, and in regions from cyclone activity, and moving dead zones.
Do adapt you need time to build up genetic diversity before the next population drop. The capacity to adapt is genetic biodiversity.
Your passenger pigeon comparison is a false equilavency. Coral can adapt immediately via symbiont shuffling and shifting and short symbiont generation time. Passenger PIgeons require far greater periods
You should also read 1491. Anthropologists found passenger pigeons were scarce due to competition with native Ameicans for nuts and seeds. The arrival of Europeans and small pox wiped out most native Americans leading to an explosion in pigeon populations
Your passenger pigeon comparison is a false equilavency.
The point is that the argument that putting extinction pressure on an animal, or worse a critical ecosystem upon which 25% of ocean species are directly dependent, to make is stronger is flawed.
Evolution happens on much longer timescales that is being suggested.
Coral can adapt immediately via symbiont shuffling and shifting and short symbiont generation time.
This must be some new meaning of “immediately”. The symbiot can appear very long distances down current, but migration across a bleached coral against the current is measured in centimetres per year.
Note also that when a coral is colonised after temperature bleaching by a more temperature-hardy symbiote, the coral does not thrive.
Anthropologists found passenger pigeons were scarce due to competition with native Ameicans for nuts and seeds.
The point is that destroying large swaths of an ecosystem, does not, in the modern age, increase the viability of the component species, any more than shooting even the most abundant bird on the continent will encourage it to evolve.
Seth says, “The point is that destroying large swaths of an ecosystem, does not, in the modern age, increase the viability of the component species”
You are again confusing the issues. Climate change has not destroyed large swaths of an ecosystem.
I agree that destroying reefs by dynamite fishing is an issue and should be stopped
Seth says, “Note also that when a coral is colonised after temperature bleaching by a more temperature-hardy symbiote, the coral does not thrive.”
That is a myopic view that is misleading. It is sometimes true more heat tolerant symbionts will produce less photosynthate, but that should be expected. When irradiance and temperature are higher than normal photosynthetic systems can tolerate, coral choose tolerant symbionts that run slower. If those extreme conditions remain, then there is not a negative effect on coral growth. However if temperatures and irradiance drop back to normal, then those less productive symbionts can create a net decrease in energy and slow coral growth. In that case the coral simply expel the more heat tolerant symbionts and re-acquire the previous types.
That is the beauty of coral’s rapid adaptation.
Evolution happens on much longer timescales that is being suggested.
================
genetics doesn’t work that way. death and extinction are the process by which life survives at the expense of the individual and the group.
Live didn’t start out with a whole lot of different species, and end up with a few as species went extinct along the way. Life started out with a few species, and ended up with many species as many more went extinct along the way.
The life forms on earth carry the genes from thousands if not millions of extinct species. And these genes are routinely turned on and off and resuffled as new species emerge and old species go extinct.
Thus we find bacteria resistant to penicillin and rats resistant to warfarin. Did the bacteria and rats develop new genes? Or did old genes resurface as required?
Seth, I know you love playing the idiot, but even you should be able to tell the difference between putting pressure on a population and an extinction event.
Evolution happens on both short and long time scales. Evolution can happen in as little as one generation.
The boring troll continues his unbroken streak of completely missing the point and generating bogus analogies.
To Mr Jim Steele
I just heard a scientist on the radio (a climate alarmist) state that when co2 was 15 times higher than present THE EQUATORIAL REGIONS of the Earth were uninhabitable. I imagine he was talking about a period when Earth had no ice at either pole & the global average temperature was much warmer than now
Would he be correct?
thanks for any response
When modern corals evolved the pCO2 was around 1,500 ppmV, which is over 5 times the pre industrial CO2 level.
From the graph at the latter link you can see the pCO2 was well over 15 times the human era level back in the Precambrian, when multicellular life evolved. Temperature too was as much as 10 C above the current level for most of the last 600 million years and life was doing quite well thank you.
Today if you watch the international weather reports you’ll see places like Baghdad are often 50 C in summer, yet humans seem to do fairly well in those cities even without good aircon. It’s all garbage.
When modern corals evolved the pCO2 was around 1,500 ppmV, which is over 5 times the pre industrial CO2 level.
From your link, modern corals evolved in the Miocene, which mostly had PCO2(atmos) peaking at around 400ppm(V). Which is almost 2 times the pre-industrial level. It averaged about pre-industrial levels.
(See figure 8 of this paper, for example).
From the graph at the latter link you can see the pCO2 was well over 15 times the human era level back in the Precambrian, when multicellular life evolved.
Unfortunately for precambrian life, while it might to well under massive global warming for temperature, there are two significant issues that mean that will not do well under the current warming.
1) Current oxygen levels would wipe them out.
2) They are extinct.
More relevant is the effect of global warming on existant species.
Temperature too was as much as 10 C above the current level for most of the last 600 million years and life was doing quite well thank you.
Is your argument that anything that is “life” can tolerate conditions of 600 million years ago, therefore “life” can tolerate a return to some aspects of those conditions?
Would you say that because camels do quite well thank you in the deserts of the Arabian Peninsular, that whales would also do quite well there thank you, because they’re both life?
I think that most people would rather look at what existant species can tolerate, and how many of each would be under extinction pressure from climate change, rather than assuming that species from an atmosphere and solar activity from the long lost past will somehow be able to transfer their capacity to live under high CO2 concentration under those circumstances to modern species trying to exist under those CO2 levels and modern conditions.
Today if you watch the international weather reports you’ll see places like Baghdad are often 50 C in summer, yet humans seem to do fairly well in those cities even without good aircon.
A series of warm nights is what kills people, and it does in Baghdad especially when the power is out, so the aircon doesn’t go.
I see that Seth is continuing his streak of just making up facts as he needs them.
Uninhabitable by what? Microorganisms live everywhere. There are some alarmist claims that equatorial regions will become too hot for humans due to climate change. Fat chance given the natural cycles and offsetting factors. IMHO, just pure alarmist blather.
As for history, where were the continents when CO2 was 15 times higher than now? The alarmists are worrying about a doubling of CO2, not 15 times now. And if it was 15 times what it is now, what was around. How would they even know – well they claim by proxies here:
http://earthguide.ucsd.edu/virtualmuseum/climatechange2/07_1.shtml
http://earthguide.ucsd.edu/virtualmuseum/images/CO2History.html
Money quote:
Also read this:
http://www.ncdc.noaa.gov/paleo/ctl/cliscibeyond.html
Interesting extinction events on the list along with sea level variation.
The article suggests that the poles were much warmer, the equator not so much. You can search this in a few minutes. 500 million years ago Godwana was over or nearly over the south pole. I suggest that you read one of our authors that posts here: “Blowin’ Smoke” because I think that the quote you heard was just that … or out of context. I could be wrong but duckduckgo.com says I am probably reasonably correct.
Alarmist brain fxrts all the way down.
There is a big debate about how warm the tropics were and how much CO2 was in the atmosphere. Most proxy data suggested the tropics were not much warmer than today. That argument is supported by clausius-clapeyron relation that shows at around 32 C additional heat causes evaporation that cools the ocean. The thermostat hypothesis suggests there is an upper limit to ocean temperatures. There have been proxy data that suggests warmer ocean temperature were possible but there are some issues regards the reliability of proxies on both sides of the debate.
Modern observations also show that warming does not cause tropical warm pools to increase in temperature, but instead the war pool expands
Also proxy data is problematic regards determining past CO2 concentrations. There were no ice caps that usually provide our more recent estimates of CO2. Climate models driven by CO2 require CO2 concentrations 3 to 10 times greater than most proxies estimate to create the warm temperatures of the Age of Dinosaurs.
Jim Steele:
Have your book and sent copies to my children. Thank you for the book and your comments here with all the detailed information collated in one place. The book with its look at water and animal habitat is an excellent read and practical. Love observation with good thinking of alternative hypotheses to consider for the results over TIME. Thanks.
Wayne Delbeke
Faraway, Alberta
Fantastic, well researched, well written article. Like a gourmet meal, where each course wets the appetite for the next.
It is really quite disappointing that academia has become stuck in the mud, resistant to change, promoting a single version of the truth. What happened to the notion that youth and universities were supposed to challenge the old ideas?
We know that bacteria, insects and animals routinely adapt to environmental change. That competition, not habitat is what limits life. Very little grows under evergreens for a reason, because the evergreen is killing the competition.
But somehow “pretty” animals can’t adapt. Why is it so hard to believe that a species that has survived for hundreds of millions of years might just have a few tricks up its tentacles?
Ants farm aphids. Why is it such a surprise to academics to learn that polyps farm algae. And when conditions change, the farmers switch crops. Just like human farmers, they plant what works for local conditions.
And when conditions change, they plant something else or starve. And if they starve, next year a new farmer takes over the farm. Because there is a lot more farmers than farm land. And in the sea there are way, way more free swimming polyps than there are shallow seas, rocky bottoms and warm water available to build reefs.
Most of the ocean bottom is mud, which is no good for corals. Corals need a hard surface. If an area of a reef dies, that is prime real estate for free swimming polyps to colonize and start reproducing. Which they do prodigiously.
Excellent article. I appreciate your effort to explain your subject in terms even an economist can understand.
Thank you Jim Steele!
It is better to light a candle than to curse the darkness.
A few years ago there was a freeze in Florida that caused coral bleaching there. It’s not always about heat…
There have been many presentations about debatable matters of global warming. This clear and logical exposition by Jim Steele is another.
Does the collective readership of WUWT not contain a single person who could encourage a scientist like Dr Hoegh-Guldberg to semi-formally respond?
Sooner or later there has to be a better path of communication between ‘sides’ here. The present stand-off, already seen time and again, is doing great harm to science overall.I don’t know the people involved here, otherwise I would be writing.
Geoff.
Politicization is toxic to science. A party line is agreed and then is forcefully imposed in defiance (denial) of real world data. The signature of pseudoscience and dysfunctional epistemology is always the same – highly inductive narratives are given precedence over deductive inferences, simulations and models given precedence over observations. There is always an arrogant assumption of knowledge which is baseless. (“Our models predict it, it does not matter that it is not observed in the real world.”) The same thing happened in the nuclear field with radiation carcinogenesis and the linear no-threshold hypothesis, also false, which also has become settled science.
Why would he _want_ to respond? Seriously, what would Dr H-G gain by doing so? Can’t you just hear the “debating them only gives them undeserved legitimacy” theme song playing?
Yah, that is known, but those who disagree must make repeated invitations to the others, so that the closed door is not attributed to them so easily.
Many thanks to Jim Steele for a beautifully written, well argued and factual article.
If only stuff like this could get out into the main media….
Chris
Great post, Jim!
Here’s a collection of recent “inconvenient” articles about coral reefs…
Ooops, part deux…
Ooops, part trois…
Ooops, part quatre…
Ooops, part cinq…
Ooops, part six…
Ooop, part sept…
This is the biggest oops of all. The Gorebots “simply do not have enough information to” know how coral reefs are coping with the weather… yet they are on the fast track to extinction because it’s part of the Gorebal Warming narative.
Oops, part huit…
Ooops, part neuf…
Ooops, part dix…
Ooops, part onze…
I’ve noticed that scuba divers tend to whine more than other groups about Gorebal Warming and Ocean Neutralization killing coral reefs. I have also noticed variations of this in several articles…
Ooops, part douze…
oops, part treize…
Ooops, part quatorze…
Ooops, part quinze…
Ooops, part seize…
Oops, part dix-sept…
Ooops, part dix-huit…
Ooops, part dix-neuf…
What is so special about Little Cayman’s reefs?
Here’s a SWAG… They are REMOTE.
Ooops, part vingt…
The Sangamonian interglacial stage is one big ass ooops for the Gorebots. Fortunately for coral reefs, there were no scuba divers 130,000 years ago.
Ooops, part vingt et un…
Scientists warn that 2 C target is not enough to protect corals
Those “scientists” need to clean their crack pipes…
Ooops, part vingt-deux…
Why does it always shock the “scientists” when they discover healthy, thriving coral reefs?
It seems as if every newly discovered reef is healthy and thriving… particularly if it is in a remote area and not frequented by scuba divers?
Oops, part vingt-trois…
Ooops, part vingt-trois A… If Acropora cervicornis and Acropora palmata can interbreed to produce genetically viable offspring (Acropora prolifera), they are not distinct species and should not be listed as endangered species. Acropora is not endangered, prolifera might be a clue.
Oops, part vingt-trois B… Coral reefs appear to be adapting quite well to climate change, if not adapting so well to scuba divers, snorkelers, agricultural runoff and fishing with dynamite.
Great addition Dave
Dave,
When I was living in the Marianas, the reefs near tourist areas were always trashed. The ones that were hard to get to were absolutely fantastic. We always taught the divers in training how to hover near the reefs, because too many newbies want to stand on the coral or grab it to stabilize themselves. Once they had buoyancy control cold, we never had any incidents in our groups.
>>Researchers are surprised at thriving coral growth at Rottnest Island.
Hardly a surprise. My PADI course was done while diving on the Rottnest reef – back in the 80s. And this is a cold-water reef. Very cold, as I remember.
R
This well written piece needs to be edited into a script for a video highlighting the beauty, variety and resiliency of coral reefs.
Such a video would reach a different and wider audience that needs to hear the logic of dynamic recovery instead of the doom & gloom spread by the “CO2 is killing everything in the oceans” alarmunists.
Dan, I would love to such a video and would gladly help in anyway. Do you know some who could produce it. My attempts to produce amateur videos were OK but would not do the issue justice.
https://www.youtube.com/watch?v=_FuKSK7kP0s
Jim Steele, My sincerest gratitude for yet another clear, concise explanation of knowledge. You are indeed a great teacher. Thank you!
This is to clarify the evolutionary history of scleractinian reef building corals. They evolved 240 million years ago in the Triassic. They thrived at first, but were pushed out of their niche by rudist reef builders during the Cretaceous when it was much warmer than today and the seas were more saline. The Rudists went extinct during the mass extinction event at the end of the Cretaceous when the dinosaurs died off. Some of the coral animals went extinct then as well. But, most of the scleractinian corals came back and thrived after the extinction event finished 60 million years ago. They took a while to come back and were not as common in the Paleocene-Eocene when both CO2 and temperatures were much higher than today. They really took off in the Oligocene and later. The temperatures and CO2 were lower in the Oligocene than in the Paleocene-Eocene, but were still much higher than today.
http://www.dailymail.co.uk/news/article-3593787/Great-Barrier-Reef-killed-two-weeks-just-one-large-coal-spill.html
Yeh right!
http://www.dailymail.co.uk/news/article-3599261/Scientists-say-10-billion-needed-save-Great-Barrier-Reef-10-years.html
http://i.dailymail.co.uk/i/pix/2016/05/12/13/3414E9B800000578-3586655-image-a-23_1463055983410.jpg
Cos it is a nice picture 🙂
Followed the link to the paper
Abstract
The Great Barrier Reef (GBR) is a World Heritage site off the north-eastern coast of Australia. The GBR is worth A$ 15–20 billion/year to the Australian economy and provides approximately 64,000 full time jobs. Many of the species and ecosystems of the GBR are in poor condition and continue to decline. The principal causes of the decline are catchment pollutant runoff associated with agricultural and urban land uses, climate change impacts and the effects of fishing. Many important ecosystems of the GBR region are not included inside the boundaries of the World Heritage Area. The current management regime for catchment pollutant runoff and climate change is clearly inadequate to prevent further decline. We propose a refocus of management on a “Greater GBR” (containing not only the major ecosystems and species of the GBR, but also its catchment) and on a set of management actions to halt the decline of the GBR. Proposed actions include: (1) Strengthen management in the areas of the Greater GBR where ecosystems are in good condition, with Torres Strait, northern Cape York and Hervey Bay being the systems with highest current integrity; (2) Investigate methods of cross-boundary management to achieve simultaneous cost-effective terrestrial, freshwater and marine ecosystem protection in the Greater GBR; (3) Develop a detailed, comprehensive, costed water quality management plan for the Greater GBR; (4) Use the Great Barrier Reef Marine Park Act and the Environment Protection and Biodiversity Conservation Act to regulate catchment activities that lead to damage to the Greater GBR, in conjunction with the relevant Queensland legislation; (5) Fund catchment and coastal management to the required level to solve pollution issues for the Greater GBR by 2025, before climate change impacts on Greater GBR ecosystems become overwhelming; (6) Continue enforcement of the zoning plan; (7) Australia to show commitment to protecting the Greater GBR through greenhouse gas emissions control, at a scale relevant to protecting the GBR, by 2025.
So they want to spend 10 beeellion on plans, regulations and commitment to control greenhouse gasses. Nice pile of treasure if you can get it for doing not much.
Follow the money….