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Corals Are Thriving in Modest Warming

May 20, 2021

Climate Change Weekly #398

Climate alarmists have long hyped an alleged threat of purported human-caused climate change to coral reefs, blaming every bleaching event on warming oceans and ocean acidification, and claiming the damage is permanent. The evidence shows these claims are untrue.

The notion that climate change could cause the extinction of coral reefs is among the least-supported but most persistent assertions climate alarmists make.

Less than 20 percent of the world’s ocean area has been mapped or explored in detail. Although coral reefs make up only 2 percent of the ocean floor, they are often called the rainforests of the ocean because of all the seagoing species that have been discovered and described, 25 percent spend all or part of their lives on or interacting with coral reefs, depending on them for food, shelter, and protection.

The oceans are far from acidic, and they are not threatened with becoming acidic from increasing carbon dioxide emissions. In fact, the oceans’ health is improved, not harmed, by increases in carbon dioxide. Carbon dioxide nourishes phytoplankton, which form the foundation of the marine food chain.

The first corals arose during the Cambrian period, about 535 million years ago. The number and types of corals increased dramatically more than 400 million years ago, when global temperatures and carbon dioxide concentrations were much higher than at present. Corals have proved adaptable, expanding their range, evolving, and thriving through periods of higher and lower temperatures than the Earth is either currently experiencing or reasonably expected to reach in the foreseeable future.

Although adaptable, corals are limited to warm waters and aren’t found near either of the frozen poles. Recent warming has allowed corals to expand their range modestly poleward while still thriving near the equator.

Bleaching is caused by a variety of factors, some known, some still unknown. For most corals in most places that have suffered bleaching, human development of one sort or another, such as chemicals (including sunscreens), silt, and waste from coastal development or commercial agriculture is a prime factor. Fortunately, many if not most of the portions of coral reefs that have suffered bleaching in recent years have already recovered.

Scientists have had no clear count of the total number of corals or coral species now in existence. Recent research, however, is changing this, and it is providing even more reason to believe corals are far from being threatened by modest climate change.

A peer-reviewed study published recently in Nature Ecology & Evolution reveals there are more than 500 billion coral colonies in the southwestern Pacific Ocean alone. The researchers note theirs is the first study to measure the number of corals in a large region. Previous estimates of coral species and colonies were all based on “qualitative expert opinion”—in other words, speculative guesses—instead of observational surveys of ocean reefs. Based on the staggeringly large and diverse number of coral and mixed coral colonies the researchers found in this one section of the Pacific, the study’s authors conclude it is extremely unlikely coral in general, or almost any coral subspecies in particular, faces extinction pressures in the foreseeable future.

Commenting on the sheer number of corals and coral species, the authors write,

Our analysis suggests that approximately half a trillion corals (0.3 × 1012–0.8 × 1012) inhabit these coral reefs, similar to the number of trees in the Amazon. Two-thirds of the examined species have population sizes exceeding 100 million colonies, and one-fifth of the species even have population sizes greater than 1 billion colonies.

As Heartland Institute President James Taylor noted in a recent Climate Realism article on this study, “The authors explain that their estimates of coral population size ‘are several orders of magnitude larger than sizes that would put them at risk of global extinction.’” This means global corals would not be at risk of extinction even if there were only 10 percent as many corals as there are now. Of course, this is just the number of corals and coral species found in a portion of the Pacific Ocean. There has yet to be similar survey of coral reefs in the Atlantic, but there is no reason to think tens to hundreds of billions more corals won’t be discovered there if such a survey is done. interviewed several of the authors of the study, including lead author Andy Dietzel, Ph.D., from the ARC Centre of Excellence for Coral Reef Studies at James Cook University. Dietzel told the journal “the eight most common coral species in the region each have a population size greater than the 7.8 billion people on Earth.”

The research contradicts the International Union for the Conservation of Nature’s (IUCN) claim that 80 coral species are facing an elevated risk of extinction. Twelve of those species have estimated population sizes of more than one billion colonies, the researchers found.

“As an example, the finger-coral, Porites nigrescens, ranks amongst the ten most abundant species we examined. It’s also not considered to be highly susceptible to coral bleaching—yet it is currently listed by IUCN as vulnerable to global extinction,” Prof. Sean Connolly, a coauthor of the study, told

Climate alarmists have made much ado about bleaching events in recent years in portions of Australia’s Great Barrier Reef. This research shows the reef is far from being destroyed. “We counted an average of 30 corals per square meter of reef habitat,” Connolly told “This translates into tens of billions of corals on the Great Barrier Reef—even after recent losses.”

Even if the number of corals making up the Great Barrier Reef were not so varied and numerous, corals have proven resilient in the face of climate change over the eons of their existence, as I noted above. Recent surveys show many of the coral colonies making up the Great Barrier Reef that have suffered bleaching have subsequently recovered or are in the process of doing so.

This study should put an end to the myth that corals are threatened with extinction by current or reasonably expected climate change. The available evidence is clear: coral reefs are numerous, and modest warning does not threaten them with extinction.

SOURCES: Nature Ecology and Evolution (behind paywall); Climate Realism;; Climate Realism; Climate at a Glance: Coral Reefs; Climate at a Glance: Ocean Acidification




New research published in the peer-reviewed journal Geophysical Research Letters compares present damage from tropical hurricanes to future damage projected by a range of climate models. After accounting for the size of hurricanes and maximum wind speed—storms’ kinetic energy— the authors project no measureable worsening of future hurricanes if the Earth continues to warm.

The international team of researchers from universities and research institutes in Spain (lead author), France, Germany, and the United Kingdom first ran climate models in a way they are commonly operated: a static fashion with no interaction between the atmosphere and oceans. The models projected smaller but more intense tropical cyclones would result. Because they were smaller in size, the overall kinetic energy, and thus destructive force, was estimated to be comparable to present hurricane conditions. When the models were run allowing a more realistic interaction between the atmosphere and oceans, the models project smaller and less-intense storms.

“Comparing cyclone integrated kinetic energy between present conditions and a projected future climate scenario did not suggest notable changes between the two periods,” the researchers conclude.

SOURCE: Geophysical Research Letters (behind paywall)


If increasing anthropogenic greenhouse gases are causing climate change, a new accounting of national greenhouse gas emissions shows China is the straw that stirs the drink. In 2019, China’s annual emissions exceeded those of all developed countries combined, for the first time. China accounted for 27 percent of global emissions in that year, the Rhodium Group report found. The United States, the second-highest greenhouse gas emitter, produced 11 percent of global emissions. India was responsible for 6.6 percent, and the European Union accounted for 6.4 percent. The United States still leads the world in per capita emissions, but China is catching up fast.

Although China has pledged to become carbon-neutral by 2060, its carbon dioxide emissions are growing dramatically. So are the emissions from India and many African and Asian countries where China is helping build hundreds of coal-fueled power plants. In addition, China does not count its emissions of other greenhouse gases toward its goal of carbon neutrality, even though gases such as methane and HFCs contribute much more warming per unit emitted than carbon dioxide, the Rhodium Group study notes.

Based on the trajectory of emissions from China and other developing countries, Climate Action Tracker calculates pledges made by world governments under the Paris climate accord and other agreements to limit carbon emissions will be woefully insufficient to meet the goal of keeping global temperatures from rising above 1.5 degrees Celsius above preindustrial levels.

SOURCES: Yahoo News; Rhodium Group


The beginning of May marked the 15th anniversary of the day the IUCN declared polar bears vulnerable to extinction because of climate change, the first time such a designation had ever been made. Research strongly suggests this classification was politically motived and was never justified. It was based solely on the opinion of a narrow group of polar bear specialists, not on data.

As Susan Crockford, Ph.D., notes in a new publication, polar bear numbers have continued increasing since the species was categorized as vulnerable by the IUCN in 2006 at the behest of the IUCN’s Polar Bear Specialist Group (PBSG).

Based on no research or data showing a threat to polar bear populations, which were on the upswing, IUCN listed polar bears as vulnerable to extinction based solely on experts’ predictions and computer model projections that a future loss of sea ice would cause polar bear numbers to plummet in the coming decades. The PBSG said climate model projections indicated “2/3 of the world’s polar bears would disappear when sea ice dropped by about 40 percent and stayed there for 10 years—which was not expected to occur until 2050.”

In fact, sea ice declined by the projected amount in 2007, and since then it has remained below or near the average level PBSG said would kill off the polar bears. Polar bear numbers increased.

Aware that their projections had proven woefully wrong, with polar bear numbers estimated at between 22,000 and 31,000 (an average of 26,000), the IUCN commissioned a new assessment of the threat to bears based on sound mathematical principles instead of opinion. The new assessment concludes that at worst, if summer sea ice remains low, “by 2050, there was a 70% chance that the population would decline by 30% or more.” This means polar bear numbers would still be above levels at which IUCN considered the species stable and safe from extinction prior to the PBSG raising the specter of climate change in 2005.

Surveys indicate the polar bear population is currently above 30,000, and realistic estimates place their numbers as high as 58,000.

This raises the question of why polar bear numbers continue to increase despite relatively low summer sea ice levels. Crockford explains:

Polar bears only require sea ice until about mid-May or mid-June (depending on the latitude) and again in the late fall (November) through the winter. As long as ice is present at those times the bears will be fine. The idea that summer sea ice is essential for polar bear survival was an early assumption made by polar bear specialists that turned out to be wrong.

[I]f polar bears really required as much summer ice as IUCN biologists assumed back in 2006, there would be fewer than 10,000 bears remaining—and that simply didn’t happen.

SOURCE: Polar Bear Science

H. Sterling Burnett, Ph.D., is the Director of the Arthur B. Robinson Center on Climate and Environmental Policy and the managing editor of Environment & Climate News.
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