CO2, pH og Koraller

" The world's oceans are likely to become more acidic than at any time in the past 14 million years, scientists have found... the pH of the oceans would be less than 7.8 in 2100.."

" Under a 'business-as-usual' future scenario where we continue to emit CO2 at the same rate as we do today, atmospheric CO2 would be near 930 parts per million in the year 2100"

" More than 75 percent of the coral reefs in the Atlantic region are at risk from local threats (i.e., coastal development, overfishing/destructive fishing, marine-based pollution, and/or watershed-based pollution), with over 30 percent in the high and very high threat categories.

The least-threatened reefs are almost entirely in areas remote from large land areas, such as the Bahamas, the southern Gulf of Mexico, and the oceanic reefs of Honduras and Nicaragua."

" Heron Island reef flat of the Great Barrier Reef show that this species exerts strong physiological controls on the pH of their calcifying fluid (pHcf).. having near-constant pHcf values independent of the large natural seasonal fluctuations of the reef flat waters (pH ∼7.7 to ∼8.3)
"

"Andreas Andersson of the Scripps Institution of Oceanography in San Diego, California, and his colleagues carefully monitored a coral reef in Bermuda for five years, and found that spikes in acidity were linked to increased reef growth.

"At first we were really puzzled by this," says Andersson. "It's completely the opposite to what we would expect in an ocean-acidification scenario.""

"The team found that coral growth itself made the water more acidic as the corals sucked alkaline carbonate out of the water to build their skeletons. The corals also ate more food during these high-activity periods and pumped more CO2 into the water, increasing acidity further.

All the pieces then seemed to fit together: phytoplankton blooms seemed to be washing in and feeding the corals, resulting in a higher growth rate and greater acidity levels in the water around the reef.
These corals didn't seem to mind the fluctuations in local acidity that they created, which were much bigger than those we expect to see from climate change. This may mean that corals are well equipped to deal with the lower pH levels.
"

" Visual surveys of colony mortality and bleaching status of more than 13,000 corals at 14 reef sites indicated that most coral taxa at wave-protected sites were severely affected by the event.

Between 40 and 75% of colonies in the major coral taxa (Acropora, Porites, Faviidae, Mussidae and Pocilloporidae) were either bleached or suffered partial mortality. In contrast, corals at wave-exposed sites were largely unaffected (<1% of the corals were bleached), as periodic washing by waves prevented desiccation."

"Our results demonstrate that coral acid-rich proteins (CARPs) not only bind Ca2+ stoichiometrically but also precipitate aragonite in vitro in seawater at pH 8.2 and 7.6, via an electrostatic interaction with protons on bicarbonate anions. Phylogenetic analysis suggests that at least one of the CARPs arose from a gene fusion. Similar, highly acidic proteins appear to have evolved several times independently in metazoans through convergence. Based purely on thermodynamic grounds, the predicted change in surface ocean pH in the next decades would appear to have minimal effect on the capacity of these acid-rich proteins to precipitate carbonates."

" Randomly arranged, amorphous nanoparticles are initially deposited in microenvironments enriched in organic material; they then aggregate and form ordered aragonitic structures through crystal growth by particle attachment. Our NMR results are consistent with heterogeneous nucleation of the solid mineral phase driven by coral acid-rich proteins. Such a mechanism suggests that stony corals may be able to sustain calcification even under lower pH conditions that do not favor the inorganic precipitation of aragonite."


"This has important implications for the health of corals in our warmer, higher-CO2 future."

Dette var input vedrørende formationen af Aragonit.
Men den anden vej, hvor hurtigt bliver Aragonit opløst ved pH niveau 7,8?

" More than 75 percent of the coral reefs in the Atlantic region are at risk from local threats (i.e., coastal development, overfishing/destructive fishing, marine-based pollution, and/or watershed-based pollution.."

" There have been 207 known impacts from tropical cyclones along the east coast since 1858. Major east coast tropical cyclones impacts include
1890 Cardwell;
1893 Brisbane;
1898 NSW;
1899 Bathurst Bay;
1918 Innisfail;
1918 Mackay;
1927 Cairns and inland areas;
1934 Port Douglas;
1949 Rockhampton;
1954 Gold Coast;
1967 Dinah, Southern Queensland;
1970 Ada, Whitsunday Islands;
1971 Althea, Townsville;
1974 Wanda, Brisbane;
2006 Larry, Innisfail."

" The response of calcification rate to temperature remained linear. Variation in annual average SST accounted for 84% of the variance. For each 1°C rise in SST, average annual calcification increased by 0.33 g cm−2 year−1...
calcification rates may have already significantly increased along the GBR in response to global climate change."

" this study demonstrates that through rapid sea level fall, the 2015–2016 El Niño has impacted Indonesian shallow coral reefs well before high sea surface temperature could trigger any coral bleaching.

Sea level fall appears as a major mortality factor for Bunaken Island in North Sulawesi, and altimetry suggests similar impact throughout Indonesia."

"Record heat in 2016 caused massive coral bleaching and death accross Auatralias Great Barrier Reef – especially in the North."

" Prof Ridd said it was difficult to see from aerial surveys whether coral at depths of 10m were bleached, while he had been unable to find out from the Prof Hughes-led researchers the depth of their underwater surveys."

" However, 20–30% of faviid colonies were bleached throughout the depth range, suggesting that the increase in benthic irradiances during extreme low tides caused light stress in deeper water. Analyses of an 8-year dataset of tidal records for the area indicated that the combination of extended periods of aerial exposure and high irradiances occurs during May–September in most years, but that the event in September 2005 was the most severe. We argue that extreme low-tide, high-irradiance events are important structuring forces of intertidal coral reef communities, and can be as damaging as thermal stress events. Importantly, they occur at a time of year when risks from thermal stress, cyclones and monsoon-associated river run-off are minimal."

" The corals could then overgrow the submerged hills, to form the present cays and reefs. Sea level here has not risen significantly in the last 6,000 years.The CRC Reef Research Centre estimates the age of the present, living reef structure at 6,000 to 8,000 years old."

1) De dystre artikler der via længere varende sammenligning af data, "trends" til tiden med færre El ninos til i dag, eller via forsøg der ikke er direkte i havet, eller ved forhold hvor man tilsætter saltsyre for at ændre pH i stedet for CO2, forsøg uden bølger osvosv. kommer til konklusioner at det ser meget svært ud for korallerne. De kan ræsonnere sig frem til at koraller er nærmest doomed og at de har meget svært ved at komme igen.

2) De mange artikler hvor forskere efter helt konkrete koral død/bleaching events i den virkelige verden kommer tilbage og konstaterer at:
"Hey..?! Korallerne klarer sig da ganske udmærket! Pyha!"

"We've seen headlines stating that 93 per cent of the Reef is practically dead. We've also seen reports that 35 per cent, or even 50 per cent, of the entire Reef is now gone.

"However, based on our combined results so far, the overall mortality is 22 per cent — and about 85 per cent of that die-off has occurred in the far north between the tip of Cape York and just north of Lizard Island, 250 kilometres north of Cairns."

"[It's] very surprising as previous studies have shown a two-to-three year delay in reproductive activity following bleaching events.
It means they have enough energy, they've recovered the zooxanthellae and the symbiosis and they even have energy to invest in reproduction and egg development."
...
What it means is the corals along the entire Great Barrier Reef, are survivors that are going to reproduce earlier than expected which could help drive quicker recovery"

" By 2005, live coral coverage had shrunk to a quarter of what it had been a few years before. The reefs had been bleached, meaning the symbiotic algae that live there had vanished. "We thought, oh my God, this is a catastrophe," says Kaufman.

But by the time of Rotjan's voyage in 2009, something incredible had happened. The reefs had started to recover. The team of scientists on board the Nai'a saw opportunity. If these reefs can recover, they thought, maybe others can, too."

"We're taking away all the diseases except for one, the climate insult, and it turns out these reefs are able to survive"

"In 2014, only four years after one of the most extreme cases of coral decline documented, abundance of juvenile and adult colonies had regained or exceeded pre-disturbance levels, and no phase-shift to macroalgal dominance was recorded."

"However, taxonomic differences in coral susceptibility to disturbances and contrasting recovery trajectories have resulted in changes in the relative composition of species."

A Pleasant Surprise: The Recovery of Bleached Panamanian Corals

"This was the most extreme coral bleaching we had ever seen since we started our studies there in 1998. We worried that many of the bleached corals would die. Unsure of what would happen, we returned last month to check on them.

Some corals were sick and others had died, but we are happy to report that much of the bleached coral has regained its color. The reef seems to be on the road to recovery"

"Scientists have witnessed a "promising" recovery in the coral reefs around the Maldives, a recent survey has revealed.
The results show that some reefs now have more live coral cover than before the catastrophic El Niño bleaching event in 1998"

"Coral reefs may be more independent and resilient than previously thought.
New research shows that an isolated reef off the northwest coast of Australia that was severely damaged by a period of warming in 1998 has regenerated in a very short time to become nearly as healthy as it was before. What surprises scientists, though, is that the reef regenerated by itself"

"But amazingly, after about six years, the surviving corals matured and began to reproduce, creating even more new colonies than before the bleaching. "They recovered, and the larvae they produced settled and survived, at much higher rates than is often reported," Gilmour said. By 2012, the reef was basically back to its old self."

" Coral Reefs Show Remarkable Ability to Recover from Near Death"

"found that reefs could rebound even from severe bleaching events, such as those that whitened more than 90 percent of a given reef in 1998."
"Reefs that have survived one bleaching event may even be more resistant to future trouble, as reefs that weathered 1998 proved even more resilient in the 2010 bleaching event off Indonesia. "Many reef corals just might be capable of adapting fast enough to survive current rates of global environmental change"

" On the other hand, marine reserves [MYNDIGHEDERNE] did not seem to offer any extra protection to coral reefs, at least off the Seychelles islands of Mahe and Praslin, even though more seaweed-eating fish were present in these no-take reserves."

Men lad os så sige at...

Koraller er elendige til at komme sig over problemer, at de ikke kan tåle pH 7,8 uanset forklaring deres Aragonit skelletter kan ikke tåle den pH som det kunne tidligere osvosv. - og lad os sige at vi på nærmest overnaturligvis kan holde fossil CO2 oppe i de aller øverste meter af oceanet trods opblanding, og lad os sige at havets buffere ikke ville afdæmpe 4 promille mere CO2 i havet over 82 år... osv..

Vejen til at vurdere at mennesket kan tvinge oceanerne til at have pH 7,8 i år 2100 OG at dette vil give problemer for koraller er umådelig lang. Der er så mange trin i den dominorække af antagelser der i sig selv har problemer at jeg personligt på nuværende ikke kan købe denne vurdering.

"We've seen half of the corals on the Great Barrier Reef killed by climate change in just two years," Mark Eakin, study author and coordinator for the US National Oceanic and Atmospheric Administration's Coral Reef Watch, wrote in an email. "This study shows that the coral reefs that have been least affected by heat stress in the past are more sensitive to heat stress than we realized. It also shows climate change threatens the diversity that is the hallmark of coral reefs."

"Under the best conditions, the fastest-growing corals take 10-15 years to come back," Eakin wrote. "Unfortunately, our recent paper in Science showed that severe coral bleaching events are now happening every six years, on average, across the world's coral reefs.

Although some of the coral has proved resistant to heat waves, those few species won't be able to maintain the diversity that is essential to coral reefs -- a hallmark of the Great Barrier Reef and the vast diversity of marine life it sustains.

*
Rapid warming and ocean acidification directly linked to Deccan volcanism and KPB mass extinction.

*
Rapid warming and ocean acidification linked to NAIP volcanism, methane degassing and PETM faunal turnover.

*
Anthropocene's CO2 input and environmental changes 12–16 × faster than PETM or KPB

*
PETM is best-case analogue for Anthropocene; KPB is worst-case analogue leading to sixth mass extinction.

In contrast, the current rapid rise in atmospheric CO2 and climate warming are magnitudes faster than at the KPB or PETM events leading to predictions of a PETM-like response as best case scenario and rapidly approaching sixth mass extinction as worst-case scenario.

"The 2016 marine heat wave caused the most severe and catastrophic coral bleaching event the Great Barrier Reef has ever experienced, the study found. Overall, these events have affected every part of the reef."

"To add insult to injury, another marine heat wave hit the Reef in 2017, with severe heat stress and bleaching striking the central region."

Current conditions on the Reef
Overview of coral reef health reports

Prior to summer 2017/2018, multiple significant impacts affected the Great Barrier Reef over the years 2016 and 2017, including severe coral bleaching, outbreaks of coral disease and crown-of-thorns starfish, and a severe tropical cyclone and subsequent flood plumes. A separate summary of these past reef health impacts is available.

Reports from the Eye on the Reef network indicate that, following summer 2017/2018, there are currently minor levels of coral bleaching, disease and damage in the Marine Park. Severe active outbreaks of the coral-eating crown-of-thorns starfish continue in the northern and central management areas, as well as in the southern Swain Reefs.

"To add insult to injury, another marine heat wave hit the Reef in 2017, with severe heat stress and bleaching striking the central region."

FL: Jeg nævner her Professor Ridd og hans indsigelser bl.a. fordi han er blevet fyret af JCU for at have indvendinger mod den konventionelle opfattelse at det er varme temperaturer der forklarer koraldøden. Ridd skulle ikke have forfulgt muligheden at det til dels kunne være lav vanstand og svage vinde der er årsagen. Der er nu oprettet protest indsamlinger til fordel for Professor Ridd og hans videre forskning og indsamlingerne går strygende. Igen synes GW-folkets intolerance og handlinger for andres synspunkter at skabe mere klimaskepsis.

Spørgsmålet er blot: når nu vi har 1000vis af forskere, der forsøger at formidle en vurdering omkring fremtidens klimaændringer, som er ganske dystre, og vi så har nogle andre personer, der ikke tror på forskningen, skal vi så lade disse personer vedvarende undergrave forskningen pga uvidenhed eller bevist manipulerende, eller skal vi finde frem til, at de faktisk tager ganske alvorligt fejl i deres måde at stykke deres historier sammen?
Jeg mener det sidste i og med, at jeg støtter tanken om, at der skal også være et godt liv til de næste generationer.

Kære Christian,

Jeg vil gerne opfordre dig til at se DR2 debatten fra i går.
Her deltog blandt andet en nu rystet klimaminister, så nu ser det ud til, at det er begyndt at dæmre for ham.

Desto mere jeg læser forskningsrapporter fra anerkendte institutioner, rapporter fra hele verden omkring øget ekstremvejr etc, desto mindre tid ved jeg, at vi har til diskussioner og istedet må kræve handlinger.

Det var engang til diskussion om der er en klimakrise, det er det for mig ikke mere.

Uden handling vil vores gode livsbetingelser reduceres alvorligt over de næste årtier, århundrede. Det bekræftes 100% af videnskaben, minus nogle ekcentrikere, som der altid vil være. Vi går mod 3 grader i dette århundrede og vi ved end ikke hvordan vi får standset op i tide. Så problemet er tydeligt og klart.

Med den erkendelse, så vil jeg sige som George Bush: enten er du med os, eller også er du imod os. Deraf også min holdning: jeg arbejder for de næste generationers ret til et stabilt klimasystem. Nogen bryder sig ikke om det, men det kan faktisk ikke siges tit nok.

Klimaproblemet er diskuteret nu i 30 40 år. Der er kun kommet øget videnskabelig evidens om bla mere ekstremt vejr. Måske ikke tornadoer? men ekstremregn, skovbrande, hedebølger er tydeligt øget.
Hedebølger iøvrigt både på land og i oceanerne.
Vi er omkring 1 grads stigning, og ingen ved præcist hvad 3 grader bringer yderligere.
3 grader er ikke et tilfældigt tal. Det er mest sandsynlige ved fordobling af CO2, måske mere, måske mindre.
Jeg siger nej tak til dette uansvarlige eksperiment.

Coral Reefs, Mangroves, and Seagrasses
17.2.4.1. Coral Reefs
Coral reefs represent one of the most important natural resources of many tropical islands. They are a source of food, beach sand, and building materials and function as natural breakwaters along the coasts of many tropical islands. They also provide habitats for many marine animals and reef fish and generate significant revenues for many small island economies through avenues such as tourism (e.g., snorkeling and scuba diving). On many islands, coral reefs are facing severe threats from climate- and non-climate-related stressors. The total areal extent of living coral reefs has been estimated at about 255,000-1,500,000 km2 (Spalding and Grenfell, 1997), of which 58% are considered at risk from human activities, according to a global assessment (Bryant et al., 1997).
Owing to their narrow temperature tolerances, some species of corals currently live at or near their thermal limits (Goreau, 1992; IPCC, 1998). SST projections (based on three variants of the Max Planck Institute ECHAM and CSIRO GCMs) suggest that the thermal tolerance of reef-building corals will be exceeded within the next few decades. Moreover, the incidence of bleaching will rise rapidly, with the rate of increase highest in the Caribbean and slowest in the central Pacific region (Hoegh-Guldberg, 1999).
There is now substantial evidence that indicates that "episodic" warming of the ocean surface, as occurs in El Niño years, leads to significant coral bleaching (Brown and Ogden, 1993; Glynn, 1993; Goreau and Hayes, 1994; Wilkinson and Buddemeier, 1994; Brown, 1997a,b; CARICOMP, 1997; Goreau et al., 1997). The major coral bleaching episodes in the past 20 years were found to be associated with periods when ocean temperature were about 1°C higher than the summer maximum. It also has been suggested that bleaching events could occur annually in most tropical oceans in the next 30-50 years (Hoegh-Guldberg, 1999). Bleaching was particularly severe and widespread during the period of the most recent El Niño episode of 1997-1998, which was considered to be the most intense such event on record. On some islands, more than 90% of all live reefs have been affected (Goreau and Hayes, 1994), with branching species generally most severely impacted (Wilkinson 1998, 1999). An assessment of the literature on coral bleaching is provided in Chapter 6.
The impact of increasing CO2 concentrations in the oceans on coral reefs is now the focus of an emerging though as yet unresolved debate. Since publication of the SAR and the Special Report on Regional Impacts of Climate Change (IPCC, 1998), it has been suggested that the ability of reef plants and animals to make the limestone skeletons that build the reefs is being reduced by rising atmospheric CO2 concentrations. Indeed, some authors suggest that based on projected CO2 concentration in the atmosphere, the calcification rate of corals would decline by approximately 14-30% by 2050 (Gattuso et al., 1999; Kleypas et al., 1999). Again, see Chapter 6 for a full evaluation of the main issues in this debate.
Chapter 6 points out that earlier IPCC assessments have concluded that the threat of sea-level rise to reefs (as opposed to reef islands) is negligible. This conclusion was based on projected rates of global sea-level rise from Warrick et al. (1996) on the order of 2-9 mm yr-1 over the next 100 years. It has been suggested that healthy reef flats will be able to keep pace with projected sea-level rise, given an approximate upper limit of vertical reef growth during the Holocene of 10 mm yr-1 (Schlager, 1999). However, the prognosis is far less positive in many small island states (e.g., in the Caribbean Sea and the Indian Ocean), where reef structures have been weakened by a variety of anthropogenic stresses. This concern also is applicable to many island countries, where reefs in close proximity to major settlements have been severely stressed. The ability of reefs to keep pace with sea-level rise also will be adversely affected by more frequent coral bleaching episodes and by reduced calcification rates resulting from higher CO2 concentrations.

The world's oceans absorb about 30% of the carbon dioxide released into the atmosphere every year, which has already resulted in a 30% increase in acidity. But carbon dioxide emissions continue to rise. If we continue to emit carbon dioxide at current rates, estimates predict that surface water will be around 150% more acidic by the end of the century. That would be the highest acidity our oceans have seen for more than 20 million years.

People all over the U.S. and the world rely on the ocean for food, income, and industry. As ocean acidity rises, these industries and food sources may be at risk. In order to help mitigate that risk, NOAA continues to invest in products like these maps in order to provide the most accurate, up to date, and user-friendly information about ocean acidification.

"It shows that bleaching events have become five times more frequent, with the average reef being affected once every 25 to 30 years in the 1980s and once every six years in 2016."

Mass coral bleaching events during the last 20 years have caused major concern over the future of coral reefs worldwide (Hughes et al., 2017). Despite these mass bleachings, little is known about bleaching frequency prior to 1979
...
Here, we use linear extensions from 44 overlapping GBR coral cores to extend the observational bleaching record by reconstructing temperature-induced bleaching patterns over 381 years spanning 1620–2001. Porites spp. corals exhibited variable bleaching patterns with bleaching frequency (number of bleaching years per decade) increasing (1620–1753), decreasing (1754–1820), and increasing (1821–2001) again.

Så "varmen" i 2016 der dræbte koraller var i høj grad lav vandstand - kunne det se ud til - og "varmen" i 2017 der dræbte koraller var primært stormen Debbie der landede lige ved Cairns / Townsend hvor bleaching skete.

Tropical corals live close to their upper thermal limit making them vulnerable to unusually warm summer sea temperatures. The resulting thermal stress can lead to breakdown of the coral-algal symbiosis, essential for the functioning of reefs, and cause coral bleaching. Mass coral bleaching is a modern phenomenon associated with increases in reef temperatures due to recent global warming. Widespread bleaching has typically occurred during El Niño events. We examine the historical level of stress for 100 coral reef locations with robust bleaching histories. The level of thermal stress (based on a degree heating month index, DHMI) at these locations during the 2015–2016 El Niño was unprecedented over the period 1871–2017 and exceeded that of the strong 1997–1998 El Niño. The DHMI was also 5 times the level of thermal stress associated with the 'pre-industrial', 1877–1878, El Niño. Coral reefs have, therefore, already shown their vulnerability to the modest (~0.92 °C) global warming that has occurred to date. Estimates of future levels of thermal stress suggest that even the optimistic 1.5 °C Paris Agreement target is insufficient to prevent more frequent mass bleaching events for the world's reefs. Effectively, reefs of the future will not be the same as those of the past.