Archives par mot-clé : Corals

Impossible research produces 400-year El Niño record, revealing startling changes

by Charles the moderator, May 7, 2019 in WUWT


University of New South Wales

Melbourne: Australian scientists have developed an innovative method using cores drilled from coral to produce a world first 400-year long seasonal record of El Niño events, a record that many in the field had described as impossible to extract.

The record published today in Nature Geoscience detects different types of El Niño and shows the nature of El Niño events has changed in recent decades.

This understanding of El Niño events is vital because they produce extreme weather across the globe with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.

The 400-year record revealed a clear change in El Niño types, with an increase of Central Pacific El Niño activity in the late 20th Century and suggested future changes to the strength of Eastern Pacific El Niños.

“We are seeing more El Niños forming in the central Pacific Ocean in recent decades, which is unusual across the past 400 years,” said lead author Dr Mandy Freund.

“There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity.”

This extraordinary result was teased out of information about past climate from coral cores spanning the Pacific Ocean, as part of Dr Freund’s PhD research at the University of Melbourne and the Centre of Excellence for Climate Extremes. It was made possible because coral cores – like tree rings – have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past. However, until now, they had not been used to detect the different types of El Niño events.

More Evidence for Rapid Coral Adaptation

by Jim Steele, April 2, 2019 in WUWT


Good news continues to accumulate regards corals’ ability to rapidly adjust to changing climates. The view of coral resilience has been dominated by the narrative of a few scientists. In the 1990s they advocated devastating consequences for coral reefs due to global warming, arguing coral cannot adapt quickly enough. Since the Little Ice Age ended, they believed rising ocean temperatures had brought coral closer to a “bleaching threshold”, a more or less fixed upper temperature limit above which corals cannot survive. Their model predicted the speed of recent global warming “spells catastrophe for tropical marine ecosystems everywhere”. Their assertions that “as much as 95% of the world’s coral may be in danger of being lost by mid-century” was guaranteed to capture headlines and instill public fear. However, a growing body of scientific research increasingly casts doubts on such alarming predictions. Unfortunately, that good news gets much less attention.

A recent peer-reviewed paper titled A Global Analysis of Coral Bleaching Over the Past Two Decades (Sully 2019) compared 20 years of ocean temperatures at which coral bleaching was initiated. From 1998 to 2006, the average sea surface temperature that initiated bleaching was 82.6 °F. But that temperature limit proves not to be “fixed” as earlier researchers incorrectly believed. From 2007 to 2017 the average temperature limit that initiated bleaching was higher, 83.7 °F. This indicates coral have been rapidly adapting to warmer regional climates much faster than once believed.

Coral Reefs in West Hawaiʽi Showing Signs of Recovery

by P. Homewood, February 21, 2019 NotaLotofPeopleKnowThat


Surveys identified 25 coral species in West Hawaiʻi. Lobe coral (Porites lobata), one of the area’s most dominant species, proved to be the most resilient—with only 50% bleaching in 2015. Cauliflower corals (Pocillopora meandrina) were hardest hit—with 98% bleaching—but recent surveys show that they are beginning to recover.

CORAL REEFS CAN TAKE THE HEAT, UNLIKE EXPERTS CRYING WOLF

by Peter Ridd, December 26, 2018 in GWPF


Scientists from James Cook University have just published a paper on the bleaching and death of corals on the Great Barrier Reef and were surprised that the death rate was less than they expected, because of the adaptability of corals to changing temperatures.

It appears as though they exaggerated their original claims and are quietly backtracking.

To misquote Oscar Wilde, to exaggerate once is a misfortune, to do it twice looks careless, but to do it repeatedly looks like unforgivable systemic unreliability by some of our major science organisations.

The very rapid adaptation of corals to high temperatures is a well-known phenomenon; besides, if you heat corals in a given year, they tend to be less susceptible in the future to overheating. This is why corals are one of the least likely species to be affected by climate change, irrespective of whether you believe the climate is changing by natural fluctuations or because of human influence.

Corals have a unique way of dealing with changing temperature, by changing the microscopic plants that live inside them. These microscopic plants, called zooxanthellae, give the coral energy from the sun through photosynthesis in exchange for a comfortable home inside the coral. When the water gets hot, these little plants effectively become poisonous to the coral and the coral throws them out, which turns the coral white — that is, it bleaches.

 

Thriving reef fisheries continue to provide food despite coral bleaching

by Lancaster University, November 29, 2018 in ScienceDaily/Nature


The unexpected results of a 20-year study into reef fisheries published in the journal Nature Ecology and Evolution this week showed fisheries being maintained despite extreme coral bleaching. Remarkably, rapid proliferation of fishes with low dependence on corals led to catches remaining stable or even increasing.

But the results also showed fishing success was ‘patchy’ and more dependent on fewer species.

Around six million people fish on coral reefs. Each year their catch — estimated to be between 1.4 and 4.2 million tonnes — provides a critical source of food and income for many millions more.

Coral Adaptation and Epigenetics

by Rud Itsvan, November 17, 2018 in WUWT


WUWT has posted several excellent articles by Jim Steele on how global warming alarmism uses corals as the poster child for warming and acidifying oceans, none of which is scientifically justified. A brief review follows, calling attention to a recently discovered additional adaptation mechanism not covered AFAIK by Jim Steele’s posts. The motivation for this post was triggered by a recent lunch with newish neighbor Charles the Moderator (CtM), and his sharing many wonderful underwater photographs of the coral reef he now dives frequently off Pompano Beach (same reef system as off Fort Lauderdale, just a few miles further north and more conveniently onshore).

Proof that Corals are Adapting to Warming Temperatures

by Coles et al., November, 11,  2018 in CO2Science


In light of the above findings, Coles et al. state the obvious, that the corals “were able to withstand elevated temperatures (31.4 °C) for a longer period of time in the current 2017 experiment” compared to the 1970 study. Consequently, they conclude that their results “indicate a shift in the temperature threshold tolerance of these corals to a 31-day exposure to 31.4 °C,” which findings “provide the first evidence of coral acclimatization or adaptation to increasing ocean temperatures.” And that observational reality should hold great bearing on the status and health of coral reefs in response to future climate change. If temperatures rise in the future, clearly, as living organisms, corals can (and do!) adapt. Alarmist predictions of their fast and ensuing demise due to global warming should not be taken too seriously.

Large stretches of coral reefs can be rehabilitated

by University of California – Davis, September 27, 2018 in ScienceDaily


For the study, published this week in the journal Restoration Ecology, researchers installed 11,000 small, hexagonal structures called “spiders” across 5 acres of reef in the center of Indonesia’s Coral Triangle. Coral diversity is the highest on Earth in that region but is threatened by human activity, including overfishing, pollution and climate change.

Between 2013 and 2015, researchers attached coral fragments to the structures, which also stabilized rubble and allowed for water to flow through freely.

A CORAL SUCCESS STORY

Live coral cover on the structures increased from less than 10 percent to more than 60 percent. This was more than what was reported for reefs in many other areas of the Coral Triangle, at a cost of about $25 per square meter.

Les coraux blanchissent depuis très longtemps

by Prof. Dr. Paul Berth, 5  septembre 2018, in ScienceClimatEnergie


Le blanchissement des coraux est un phénomène dont on entend souvent parler dans les médias. Il s’agirait d’un grave problème environnemental, dont la fréquence augmente, et qui pourrait mener à la perte totale des récifs coralliens. Le réchauffement climatique global, qui serait causé par l’augmentation de la concentration atmosphérique en CO2 est, bien entendu, pointé du doigt. Cependant, le blanchissement des coraux n’est-il pas un phénomène très ancien? Est-il seulement causé par des variations de température? Quel recul avons-nous à ce sujet? Une récente publication de Nicholas Kamenos et Sebastian Hennige, deux chercheurs anglais des Universités de Glasgow et d’Édimbourg, apporte de nouveaux éléments.

Remember when they told us coral bleaching was a sure result of recent man-made global warming? Never mind.

by Anthony Watts, August 17, 2018 in WUWT


From the “science eventually self-corrects” department, new science showing coral bleaching of the Great Barrier Reef is a centuries-old problem, well before “climate change” became a buzzword and rising CO2 levels were blamed.

Marc Hendrickx writes:

New paper shows coral bleaching in GBR extending back 400+ years.

New Study Shows Some Corals Might Adapt to Climate Changes

by Anthony Watts, August 4, 2018 in WUWT


UM Rosenstiel School-led study exposes two threatened corals to future climate change conditions

MIAMI—New research shows that not all corals respond the same to changes in climate. The University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science-led study looked at the sensitivity of two types of corals found in Florida and the Caribbean and found that one of them—mountainous star coral—possesses an adaptation that allows it to survive under high temperatures and acidity conditions.

“Stressful periods of high temperature and increasingly acidic conditions are becoming more frequent and longer lasting in Florida waters,” said Chris Langdon, marine biology and ecology professor and lead author on the new study. “However, we found that not all coral species are equally sensitive to climate change and there’s hope that some species that seemed doomed may yet develop adaptations that will allow them to survive as well.”

See also (in French) here and  here

Corals use epigenetic tricks to adapt to warmer and “more acidic” water

by JoNova, June 12, 2018 inJoNovaBlog


After half a billion million years of climate change, I’m shocked, shocked I tell you, that life on Earth (and specifically corals) have so many ways to cope with the climate changing. After all, it’s natural (if you are trained by Greenpeace) to assume that corals can only survive in a world with one constant stable temperature just like they never had.

One more tool in the coral-reef-workshop

Corals don’t just have a tool-box, they have a Home Depot Warehouse. h/t to GWPF

(..)

More Proof of a Biological Control on Coral Calcification

by Ross C.L. et al., 2017, June 10, 2018 in CO2Science


The global increase in the atmosphere’s CO2 content has been hypothesized to possess the potential to harm coral reefs directly. By inducing changes in ocean water chemistry that can lead to reductions in the calcium carbonate saturation state of seawater (Ω), it has been predicted that elevated levels of atmospheric CO2 may reduce rates of coral calcification, possibly leading to slower-growing — and, therefore, weaker — coral skeletons, and in some cases even death.

As we have previously pointed out on our website, however (see The End of the Ocean Acidification Scare for Corals and A Coral’s Biological Control of its Calcifying Medium to Favor Skeletal Growth), such projections often fail to account for the fact that coral calcification is a biologically mediated process, and that out in the real world, living organisms tend to find ways to meet and overcome the many challenges they face; and coral calcification in response to ocean acidification is no exception.

(…)

See also in French

Evidence for the Thermal Bleaching of Porites Corals From 4.0 ka B.P. in the Northern South China Sea

by S. Xu et al., December 2017, in AGU1000Biogeosciences


Coral bleaching is becoming a serious issue for coral reefs under the stress of global warming. However, whether it has occurred in the past in times of thermal stress remains unclear. Moreover, an understanding of historic coral bleaching events would greatly improve our insight into the adaptive capabilities of corals under such stresses. It is known that Porites corals, a massive coral, have relatively high levels of symbiotic zooxanthellae and a strong thermal tolerance when compared with most other corals (and particularly branched corals). Thus, growth hiatuses and/or mortality surfaces of fossil Porites may be used to indicate past ecological or environmental stress events, such as severe bleaching. In this study, monthly geochemical and isotopic environmental proxies of four fossil Porites corals with well‐preserved growth hiatuses and mortality surfaces (aged 3,800–4,200 years before 2013 A.D.), collected from Wenchang fringing reef, Hainan Island, Northern South China Sea were analyzed. Specifically, the Sr/Ca, δ18O, and δ13C were measured with a monthly resolution for each sample.

Bleaching of coral reefs reduced where daily temperature changes are large

by University of California – Irvine, April 26, 2018 in ScienceDaily


By taking a closer look, scientists find resilience in face of heat stress.

Coral reef bleaching is stark evidence of the damage being inflicted by global climate change on marine ecosystems, but a research team has found some cause for hope. While many corals are dying, others are showing resilience to increased sea surface temperatures, pointing to possible clues to the survival and recovery of these vitally important aquatic habitats (…)

See aslo here