Ocean Acidification

Doom Never Goes Out of Fashion: The Problem With PIK’s “Planetary Health Check”

On September 21st, the Potsdam Institute for Climate Impact Research (PIK) released its 2026 Planetary Health Check, an annual report now authored, we are told, by more than 60 scientists.

The “planetary boundaries” framework, first proposed in 2009, holds that nine interlinked Earth-system processes must remain within defined “safe limits” to preserve planetary stability.

A satirical illustration featuring a woman in a dramatic black dress made of various alarming phrases, representing climate issues. She stands in front of an audience, with a humorous emphasis on catastrophic themes like 'Climate Breakdown' and 'Ecosystem Collapse'. In the background, a shopkeeper promotes the 'Doom Boutique' with customer reviews highlighting skepticism about data.

From Tilak´s Substack

By Tilak Doshi

A healthcare professional holds a small globe in both hands, symbolizing global health and care.

On September 21st, the Potsdam Institute for Climate Impact Research (PIK) released its 2026 Planetary Health Check, an annual report now authored, we are told, by more than 60 scientists. The Guardian duly reported, as it always does, the verdict with the gravity the occasion apparently demanded: the planetary life-support systems on which humanity depends have deteriorated to their worst levels ever recorded, and seven of nine “planetary boundaries” are now breached at their “highest ever levels of transgression”.

The seven transgressed boundaries, PIK tells us, are climate change, biosphere integrity, land-system change, freshwater change, biogeochemical flows, novel entities and ocean acidification. Only stratospheric ozone and atmospheric aerosol loading remain, for now, within bounds. Having delivered this verdict, PIK’s sixty co-authors extend the traditional mercy of the apocalyptic genre: salvation remains possible, if only humanity accelerates action to “return to the safe operating space” and thereby secures “shared future prosperity”. It is a formula as old as the genre itself — diagnose civilisational catastrophe, then offer just enough hope to keep the reader turning the page, or better still, funding the institute.

These cycles of doom repeat themselves regularly (remember the Club of Rome’s 1972 report Limits to Growth anyone?) The PIK report is simply the latest instalment. It deserves to be read carefully, not because its science is compelling, but because its rhetorical machinery — the appeal to consensus, the confusion of value judgement with measurement and the use of pseudo-scientific “tipping points” is now so deeply embedded in Western policy discourse that it has driven trillions of dollars in investment and regulation.

Nine boundaries, one big assumption

The “planetary boundaries” framework, first proposed in 2009, holds that nine interlinked Earth-system processes must remain within defined “safe limits” to preserve planetary stability. It is a seductive idea: a single dashboard, nine dials, and a simple readout of humanity’s report card. The trouble is that these ‘dials’ have no scientific content. As the Breakthrough Institute noted in its detailed review of the concept’s scientific foundations, the great majority of the nine boundaries — land-system change, biosphere integrity, nitrogen and phosphorus flows, freshwater use, aerosol loading and novel entities — have no identified global biophysical “tipping point” at all.

Infographic illustrating the Planetary Boundaries framework, highlighting nine environmental thresholds: Stratospheric Ozone Depletion, Atmospheric Aerosol Loading, Ocean Acidification, Freshwater Change, Land System Change, Climate Change, Biogeochemical Flows, Novel Entities, and Biosphere Integrity, including indicators of safe operating space and increasing risks.

Climate change and ocean acidification are nominally the exceptions, in that both have genuinely global physical drivers — but a global driver is not the same thing as a well-quantified, catastrophic one. MIT’s Richard Lindzen has long argued that the roughly one degree Celsius of warming observed since the pre-industrial era is consistent with a climate sensitivity to doubled CO₂. This is well below the range built into the models PIK and the IPCC rely on and sits comfortably within the bounds of natural climate variability.

Ocean acidification fares no better under scrutiny: the ocean’s average surface pH, still solidly alkaline at around 8.1, has fallen by roughly 0.1 units since industrialisation — a shift that, as shown by field studies of natural pH variability documented by Matt Ridley, is dwarfed by the swings that reef and open-ocean sites already experience within a single day or season. Neither of PIK’s two supposedly rigorous, globally-driven boundaries survives contact with the underlying data appreciably better than the other seven.

A single global number for a process that operates locally is not a scientific measurement. It is an arbitrary value judgement presented with the authority of a measured threshold. The entire framework, moreover, treats the Holocene — the roughly 12,000-year climatic interval since the last ice age — as the one true “safe operating space” for humanity, as though any departure from Holocene baselines were self-evidently catastrophic. Yet, as critics of the concept have long pointed out, many of the very changes PIK now labels “transgressions” — expanded fertiliser use, land conversion for agriculture, freshwater withdrawal, higher atmospheric CO₂ — are precisely what enabled large-scale agriculture, mass nutrition and the extraordinary rise in human welfare over the past two centuries. There is remarkably little evidence that crossing any of PIK’s chosen numbers produces a sudden, planet-wide collapse in habitability.

Consider the report’s headline climate metric: the 350 parts-per-million CO₂ boundary. This figure did not emerge from an IPCC consensus process. It originated with James Hansen’s 2008 paper, adopted wholesale into the planetary-boundaries architecture. What the “breach” framing omits is the geological record: for most of the past 500 million years, atmospheric CO₂ has run at several multiples of today’s level, and life did not merely survive those eras but flourished in them.

NASA’s own satellite data confirm as much now: a landmark NASA-funded study attributes the bulk of the global greening observed since the 1980s — new leaf cover equivalent to twice the area of the continental United States — directly to rising CO₂ fertilising plant growth. Princeton physicist William Happer, in written testimony to Germany’s Bundestag, has gone further, arguing that CO₂ concentrations have in fact been dangerously low across most of the recent geological past, and that additional CO₂ is a net benefit to agriculture, forestry and photosynthetic life generally. None of this fits the “massive and dangerous breach” framing.

The Limits to Growth, redux

None of this is new. PIK’s “planetary health check” stands squarely in the tradition of the Club of Rome’s 1972 report The Limits to Growth, which ran a computer model of five interacting global variables — population, agriculture, resources, industrial output, and pollution — and concluded that unchecked growth would collide with natural resource limits within a matter of decades. The model’s arbitrary assumptions produced arbitrary conclusions, dressed in the borrowed authority of systems science and computer modelling. Economists at the time savaged the exercise as an elaborate apparatus concealing unfalsifiable claims.

Malthusian gloom, in other words, never really goes out of fashion; it merely changes its wardrobe. Where the Club of Rome had mainframe computers and system dynamics diagrams, PIK has Earth-system modelling and a “Planetary Health Check” branded website. The underlying choice on offer, then as now, is the same: either humanity abandons industrial civilisation or it faces Armageddon. I have written before about how this framing has resurfaced in the contemporary ‘degrowth’ movement, which dresses the same anti-growth instinct in the more marketable language of ‘wellbeing economics’ and planetary limits. PIK’s report is simply the scientific-sounding scaffolding on which that political project is built.

Sixty scientists, zero falsifiability

There is an old, likely apocryphal, story about Albert Einstein. Confronted with a pamphlet titled 100 Authors Against Einstein which denounced the theory of relativity, he is said to have remarked that if he were wrong, one scientist with proof would have been enough. The anecdote endures because it captures something true about science: authority by headcount is not evidence. Sixty PIK co-authors signing a report is a demonstration of institutional consensus, not of a tested and falsifiable hypothesis. Science, as Karl Popper argued, proceeds by proposing hypotheses that can in principle be proven wrong and then rigorously trying to prove them wrong — not by assembling ever-larger committees of agreement. A plurality of scientists agreeing has, historically, been wrong before; the early 20th century’s favourable view of eugenics was also, in its day, a consensus position among credentialed experts.

Judged by that Popperian standard, PIK’s “planetary health check” fails at the very first hurdle. Its “tipping points” — the supposed thresholds beyond which Earth systems flip irreversibly into a new and debilitated state — are treated throughout as settled fact rather than contested hypothesis. Yet large, complex equilibrium systems generally do the opposite of what catastrophist framing assumes: when perturbed, they tend back towards equilibrium, as described by Le Chatelier’s principle. The “tipping point” is a scare quote with no scientific content.

The German science blog Klimanachrichten has made precisely this case against PIK directly, in an analysis summarised and translated by No Tricks Zone. Its central argument is that PIK researchers routinely interpret ordinary statistical noise in climate data — natural, historically unremarkable fluctuations — as evidence of a permanent, accelerating catastrophe. On this reading, the “accelerations” PIK reports are not statistically distinguishable from background variability. “Tipping points,” the critique continues, function for PIK less as a proven physical mechanism than as a psychological instrument: a way of instilling fear and shaping policy that borrows the vocabulary, but not the evidentiary discipline, of science.

This is hardly a new complaint against the doom-forecasting industry. The Competitive Enterprise Institute has catalogued more than 50 years of confidently declared environmental deadlines — mass starvation, resource exhaustion, the ‘end of oil’, ice-free summers by dates now long past — that have come and gone without incident. The predictions fail; the institutions and the Al Gores issuing them rarely pay a reputational price, and the doom-forecasting business simply issues an updated deadline. PIK’s 2026 report reads as this year’s instalment of a genre that has been wrong, repeatedly and specifically, for half a century, without noticeably updating its priors.

What is it about the Germans?

Ideology has a near-miraculous capacity to reshape how intellectual elites misperceive objective reality and impose their views by compliant mass media which amplify the ideology into received wisdom. Germany’s climate politics offer a case study. There is a peculiar metaphysical puzzle at the heart of all this well captured by Rupert Darwall’s book on the totalitarian roots of the climate industrial complex that deserves more attention than it gets. PIK is a German institution, and Germany today presents one of the odder spectacles in the industrialised world. Sixty German scientists confidently inform the world that industrial civilisation must be reined in after the country dismantled its own nuclear and coal capacity in moralistic fervour – deindustrialising its own economy, felling millennia-old Teutonic forest for wind turbines that cause habitat loss and kill birds of prey, and exporting, through institutions like PIK, an ‘end of the world’ mania to the rest of Europe and beyond. It is an industrial civilisation that appears, in its official climate discourse, to have turned against itself, sacrificing the welfare of its citizens at the altar of Gaia.

Adaptation, not apocalypse

The question that PIK-style reports systematically avoid is the William Nordhaus question: given real but modest and manageable warming, what is the economically optimal, gradual path of adaptation and carbon pricing, as opposed to the demand for immediate, sweeping transformation justified by worst-case unscientific “tipping-point” scenarios? Even the Nordhaus question is overstated. As William Happer and W. A. van Wijngaarden show, CO₂’s strong absorption bands are already largely saturated, so each extra increment of the gas traps far less heat than the last in a logarithmic function. The “planetary-boundaries” framework, dressed up annually as a “health check”, presents an essentially political judgement. The planet is not a medical patient, and it has no need for doctors prescribing a modern version of bloodletting as a cure.

A patient’s chart is only as good as the thresholds written on it. When those thresholds are arbitrary, unfalsifiable and renewed every September with the same verdict — worse than ever, but redeemable if only we act right now — readers would do well to ask not whether the planet is sick, but whether the diagnosis was ever really about the planet at all.

The 60 doctors at PIK are fake and doom-mongering never goes out of fashion; it only changes its letterhead.

This article was first published in the Daily Sceptic https://dailysceptic.org/2026/09/27/doom-never-goes-out-of-fashion-the-problem-with-the-planetary-health-check/

Dr Tilak K. Doshi is the Daily Sceptic‘s Energy Editor. He is an economist, a member of the CO₂ Coalition and a former contributor to Forbes. Follow him on Substack and X.

If Every Volcano on Earth Erupted at Once, Humanity Wouldn’t Stand a Chance

It would be a near- extinction- level catastrophe for humanity and most complex life, driven primarily by global ash fallout, a severe volcanic winter, acid rain, and collapse of ecosystems and infrastructure, though it is vanishingly unlikely to occur.

A dramatic scene depicting multiple erupting volcanoes with flowing lava and dark stormy skies, surrounded by a smoky atmosphere and a distant city in the foreground. — AI generated by Grok

There are roughly 1,350-1,500 potentially active volcanoes on land worldwide (about 500 have erupted in historical time), concentrated especially along the Pacific “Ring of Fire”, plus many more undersea volcanoes along mid- ocean ridges that are not fully counted. These are driven by localized magma systems, so simultaneous eruption of all of them would require an impossible coincidence of independent processes.

Immediate effects (hours to days)

Explosive eruptions (stratovolcanoes and any supervolcanoes such as Yellowstone) would produce pyroclastic flows, lava bombs, and shock waves that devastate areas near the volcanoes, collapsing buildings, triggering landslides, and generating tsunamis from undersea or coastal activity.

Ash columns would reach the stratosphere in many cases. Ash is dense (roughly five times denser than water in bulk deposits) and would quickly blanket regions, collapsing roofs, clogging engines and filters, contaminating water supplies, and grounding all air travel. Planes already airborne near eruptions would face extreme risk.

Local death tolls near active volcanic zones (parts of Indonesia, Japan, the western Americas, southern Europe, etc.) would be enormous, but these would be dwarfed by later global effects.

Atmospheric and climate impacts (days to years)

Volcanic ash and especially sulfur dioxide (SO₂) injected into the stratosphere would form sulfate aerosols that reflect sunlight.

Even a single large eruption like Tambora in 1815 cooled the Northern Hemisphere by ~0.5°C and caused the “Year Without a Summer”. Scaling to all volcanoes (including multiple VEI 7- 8 events) would produce far thicker global coverage.

Skies would darken dramatically or turn to prolonged twilight/darkness in many regions as ash and aerosols block sunlight.

Global temperatures could drop by several degrees Celsius (estimates for multiple supervolcanoes reach ~15°C temporarily in extreme scenarios), triggering a volcanic winter lasting months to years. Photosynthesis would collapse, killing most plants and crops.

Acid rain from sulfur compounds would poison soils, freshwater, and further destroy remaining vegetation and infrastructure.

Ocean acidification from gases and ash would harm shellfish, corals, and marine food webs.

Agriculture and food systems worldwide would fail rapidly.

Famine, respiratory illness from ash, and infrastructure breakdown (power grids, transport, water treatment) would kill the vast majority of people even far from volcanoes. Experts describe the result as many times worse than a nuclear winter.

Longer- term effects (years to decades and beyond)

Once aerosols settle, the large release of CO₂ could eventually drive significant greenhouse warming, potentially shifting the climate in the opposite direction after the cold phase.

In extreme interpretations involving massive magma outpourings, some speculative accounts raise the possibility of severe long- term heating or even mass imbalances that could slightly alter Earth’s rotation or axial tilt (drawing analogies to ancient events on Mars), though this is far less certain.

Most complex surface and marine life would face mass extinction.

Microbial and extremophile life would likely persist in protected niches.

Human civilization as we know it would end.

Survival of isolated groups in less- affected or underground or other protected locations is theoretically possible but extremely limited by the global environmental collapse.

In short, the planet itself would survive, but the biosphere and human society would be devastated on a scale comparable to or exceeding past mass- extinction events linked to massive volcanism (e.g., flood basalt episodes). Fortunately, volcanoes are independent systems; simultaneous global eruption is not a realistic geological risk.

Ocean “Acidification” — Another Fake Scare That Won’t Go Away

Dammed, doesn´t matter if the pH is 8.12 or 8.04. Every chemist laughs about this panic.

From Manhattan Contrarian

By Francis Menton

Ocean “acidification” is a somewhat unique branch of the overarching climate scare. It differs from other branches of the big scare in that it does not depend on atmospheric heating as the driver of the supposed scary consequences. Instead, with ocean “acidification,” the idea is that increased CO2 in the atmosphere (from the burning of fossil fuels) leads to increased CO2 dissolved in the oceans, which leads to lower pH of ocean water, which then becomes the driver of the alleged scary consequences. Thus, ocean “acidification” can theoretically work as a scare even if the atmosphere fails to heat with increasing CO2 content to the extent predicted by advocates’ climate models.

But the ocean “acidification” claim has its own frailties. For advocates of apocalyse, it is a problem that the ocean is (somewhat) alkaline, rather than acidic, and that the change in ocean pH from even large increases in CO2 in the atmosphere is small. Some might even call the change in ocean pH “slight.” And the pH change, even in worst-case scenarios, is not nearly enough to bring it down to the level of neutrality, let alone acidity. The last point is the reason that I have been putting the term “acidification” in quotes.

So, how can advocates make ocean “acidification” into something sufficiently scary to motivate lots of people to hate or fear fossil fuels? Well, perhaps they could manufacture a claim that somewhat lower pH would kill all the tropical fish. OK, but the claim could not be that slightly lower pH will directly kill the fish — nobody would ever buy that. There would have to be a different mechanism.

Several years ago (May 2021) I had a post covering the work of a pair of researchers in Australia who had come up with a claim fitting just this description. The researchers in question were Philip Munday and Danielle Dixson of James Cook University in Queensland. Over the course of multiple years and some 22 peer-reviewed papers, those two (and co-authors) had put forth a claim that lower ocean pH would drive tropical fish crazy, or at least cause the fish to experience “profound behavioral and sensory impairments” that would imperil their survival. As should be obvious, this claim gave extraordinary support to the anti-fossil fuel narrative, independent of any claim of global warming, and as a result gave the papers a very high profile, and brought the authors great acclaim.

But it was too good to be true. The occasion for my May 2021 post was a paper that had appeared in Nature in 2020, by authors Timothy Clark, et al., reporting on the results of efforts to reproduce the Munday/Dixson results. Excerpt from the abstract:

Here, we comprehensively and transparently show that—in contrast to previous studies—end-of-century ocean acidification levels have negligible effects on important behaviours of coral reef fishes, such as the avoidance of chemical cues from predators, fish activity levels and behavioural lateralization (left–right turning preference). Using data simulations, we additionally show that the large effect sizes and small within-group variances that have been reported in several previous studies are highly improbable. Together, our findings indicate that the reported effects of ocean acidification on the behaviour of coral reef fishes are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO2 oceans.

The abstract does not contain the word “fraud,” but the article contains strong suggestions of data manipulation. This was a very unusual piece for Nature to publish, given the harm it caused to a significant underpinning of the anti-fossil fuel narrative.

Here we are now, five years on. Does anything remain of the “ocean acidification” narrative as a reason to hate fossil fuels?

The past few months have seen pieces laying out the cases both for and against believing that “ocean acidification” is a significant environmental concern. On the side of “ocean acidification is really bad and scary,” I will highlight a piece by Dana Nuccitelli that appeared in something called The Invading Sea in March, title “Fossil fuel pollution’s effect on oceans comes with huge costs.” On the side of “ocean acidification is way overblown,” I will highlight a May 13, 2026 paper by van Wijngaarden, Ridd, Cornell and Happer, title “Acidification of Water by CO2.”

Nuccitelli is a frequent writer at Yale Climate Connections (yet another black eye for Yale). In Nuccitelli’s piece, he appears to have given up on trying to claim that changing pH is killing off the tropical fish. So instead, here, he emphasizes the effect on coral. He claims that “acidification” is killing off coral, but can’t attribute dying coral just to pH, so he throws in warming as well:

Florida’s barrier reef is in trouble – and it’s costing us. The reef has been experiencing a severe outbreak of stony coral tissue loss disease over the past decade. The likely cause: stress from the warming climate and acidifying waters, both the result of burning fossil fuels. . . . Human burning of fossil fuels affects Earth’s oceans via the one-two punch of warming and acidifying waters, which occurs as carbon dioxide is absorbed into the ocean.

No quantitative information is provided for the amount of coral loss, if any. The “likely cause” of the disease is said to be a combination of “warming” and “acidifying waters.” How does he know that? How much from each? Is there any actual proof? If so, Nuccitelli does not choose to cite it. I guess it’s just obvious to his readership.

After asserting the “likely cause,” Nuccitelli moves on to calculating the cost, not of the portion of the coral that may be lost, but of the entire tourism industry related to all the coral:

The financial stake of losing the reef is high. Florida’s coral reefs are estimated to draw in over $1 billion in tourism revenue each year, provide $650 million in flood protection benefits and support over 70,000 jobs. What’s more, coral reefs protect people and property by dissipating up to 97% of wave energy, lessening storm surges.

And then Nuccitelli goes on to rely on a recent paper from Nature Climate Change (from January 2026) that purports to calculate a new measure of “social cost of carbon” on an assumption that global warming will significantly decrease the productivity of the oceans, not just for coral, but all other life. The NCC paper does not appear to deal with the acidification issue at all.

Here’s my favorite chart from Nuccitelli’s article on the subject of “acidification”:

It looks like the ocean pH is dropping like a stone! Do you notice anything odd? The entire vertical scale of the chart goes from pH of 8.03 to 8.11 — less than 0.1 of a pH unit. The full pH scale goes from 0 to 14. If you plotted this line with a vertical scale going all the way from 0 to 14, the line would be indistinguishable from horizontal.

If you are interested in the question of whether ocean corals are increasing or decreasing around the world, I can recommend several pieces to you from Peter Ridd. Ridd is a guy who actually goes out and studies the corals (he was formerly at James Cook University, like Munday and Dixson, until he got thrown out for heresy). He is also the same Ridd who is a co-author on the van Wijngaarden, et al., paper further discussed below. Here is a piece Ridd wrote in 2023 for the Global Warming Policy Foundation called “Coral in a Warming World, Causes for Optimism”; and here is one from August 2025 from the Institute of Public Affairs, title “Science group think flounders on state of Great Barrier Reef.” The bottom line is that there is plenty of evidence that coral reefs worldwide are thriving (not everyone, and not every year, but on an aggregate basis), and no evidence at all of aggregate decline. In light of that evidence, what is the proof that “acidification” is harming corals? The answer is, zero.

In contrast to Nuccitelli’s evidence-free advocacy piece, the van Wijngaarden, et al., paper is a serious piece of scientific work. I note that it appears on the website of the CO2 Coalition, rather than in one of the “prestige” scientific journals. I infer that these authors, who actually are the best scientists to address this topic, have given up on the enforced groupthink of these “prestige” magazines.

The paper is long (55 pages), and much of it is technical. But the bottom line is that it is preposterous to believe that the slight decline in ocean pH caused by increased atmospheric CO2 can cause any significant problem for ocean life. In this blog post, I will only provide a summary quote. From the Abstract:

Fundamental inorganic chemistry shows that increasing concentrations of atmospheric CO2 will have no harmful effect on organisms that live in the natural waters of the Earth [1] and may well benefit them. Alkalinity and dissolved CO2 give high buffering capacity to most natural waters and minimize the change of pH from external influences. For example, doubling the atmospheric concentration of CO2 from 430 ppm to 860 ppm would reduce the pH of representative sea water at a temperature of 25 C from pH = 8.18 to pH = 7.93. This change is comparable to diurnal pH changes in biologically productive surface waters, due to photosynthetic fixation of dissolved inorganic carbon during the day and respiration at night. The change is also less than the variations of pH with latitude, longitude and depth in the oceans.

A key point is that the pH of the ocean is not a fixed number for the whole world at a given point in time. Rather, pH varies within small ranges based on latitude, longitude, depth, and even time of day. The result is that ocean life already has to deal with these ranges.

A big part of the paper deals with the chemistry of how much the pH of the ocean might be affected by increase in atmospheric level of CO2 from the current 430 ppm up to even a doubling of same to 860 pm. Some mathematics is involved, but I think it is basic and well-known chemistry. The conclusion, as stated in the abstract, is that the average pH could go down all the way to 7.93 — still well into the alkaline range (neutral is 7, alkaline above 7, and acid below 7).

If anyone is aware of research establishing that pH variation in the ranges indicated are some kind of grave threat to ocean life, I would be eager to be made aware of it. Until I see that, my conclusion is that the whole “ocean acidification” thing is no more than an effort to play on the idea that people will find the word “acid” scary.

Acidification of Water by CO2

Fundamental inorganic chemistry, equilibrium constants, buffering, and carbonate system dynamics show that rising atmospheric CO₂ causes only very small, non-harmful changes in the pH of natural waters, especially the ocean. The ocean is strongly buffered and remains highly supersaturated with respect to calcium carbonate (calcite/aragonite) even at much higher CO₂ levels.

From The CO2 Coalition

W. A. van Wijngaarden
Department of Physics and Astronomy, York University, Canada

P. Ridd
Physicist, Adjunct Fellow, Institute of Public Affairs, Malanda, Queensland, Australia

M. Cornell
Industrial Chemist, Lake Jackson, Texas, USA

W. Happer

Department of Physics, Princeton University, USA

Abstract
Fundamental inorganic chemistry shows that increasing concentrations of atmospheric CO₂ will have no harmful effect on organisms that live in the natural waters of the Earth [1], and may well benefit them. Alkalinity and dissolved CO₂ give high buffering capacity to most natural waters and minimize the change of pH from external influences. For example, doubling the atmospheric concentration of CO₂ from 430 ppm to 860 ppm would reduce the pH of representative sea water at a temperature of 25 C from pH = 8.18 to pH = 7.93. This change is comparable to diurnal pH changes in biologically productive surface waters, due to photosynthetic fixation of dissolved inorganic carbon during the day and respiration at night. The change is also less than the variations of pH with latitude, longitude and depth in the oceans. This paper includes a quantitative review of the carbonate chemistry of seawater and freshwater, the buffering capacity, the Revelle factor, the transport of calcium carbonate in ground water, the formation of flowstone, and the classic use of limewater to detect gaseous CO₂. The paper concludes with a brief review of those parts of chemical thermodynamics that are involved in ocean acidification.

Keywords: ocean acidification, pH, alkalinity, buffering, carbonate chemistry, groundwater

1 Introduction

Natural surface waters and rainwater contain dissolved CO₂, in equilibrium with atmospheric CO₂. As atmospheric CO₂ concentrations increase, the increase of the dissolved weak acid, CO₂, will lower the pH of the waters. Fig. 1 shows how the pH of representative seawater and rainwater depend on the partial pressure P of CO₂ [1].

The lowering of the pH of natural surface waters by more atmospheric CO₂ is often called acidification, but this term can be misleading. For example, representative seawater at a temperature T=25 C is quite basic, with a pH = 8.18 at current partial pressures, Pc=430 μb of CO₂. Doubling the partial pressure of CO₂ to Pd=860 μb would decrease the pH of the ocean to pH = 7.93, a decrease of ΔpH=−0.25. This would leave the oceans almost as basic as today. At the same temperature, T=25 C, doubling of CO₂ would reduce the pH of rainwater, which is slightly acidic because of dissolved CO₂ and with no compensating alkalinity, from pH = 5.59 to pH = 5.44, an even smaller decrease of ΔpH=−0.15. Although contemporary seawater has absorbed about 120 times more CO₂ per unit volume than rainwater in equilibrium with the same partial pressure P of CO₂, the relatively large alkalinity [A] = 2.4 mM of seawater keeps it basic.

In subsequent sections we will show straightforward ways to calculate the numbers cited here. Lord Kelvin once said [2]:

“When you can measure what you are speaking about, and express it in numbers, you know something about it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts advanced to the stage of science.”

As Lord Kelvin urged, much of the discussion below is in terms of numbers, equations and graphs. We have simplified discussions of the complicated chemistry of the oceans and the biochemistry of ocean life to keep the paper understandable to readers who recall some high school mathematics, chemistry and biology. More details can be found in the literature cited.

The oceans will remain non-acidic for any credible scenarios of human emissions of CO₂ in the future. This paper gives a quantitative discussion of why increasing concentrations of atmospheric CO₂ will not cause harmful acidification of natural waters on Earth, and will have little effect on the biochemistry of aquatic organisms.

Download the full publication using the link: Acidification of Water by CO2

A case for ‘Climate Humility’: Analyzing the DOE’s ‘A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate’

Yesterday’s release of the DOE’s A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate is a watershed moment in the ongoing debate over climate policy in America. Why? Because for the first time, a major U.S. government agency—on official letterhead and with a blue-ribbon cast of authors (John Christy, Judith Curry, Steven Koonin, Ross McKitrick, and Roy Spencer)—has published an open challenge to the central claims, data handling, and even the motivations behind mainstream climate science and policy.

A split image showcasing two coastal scenes; on the left, a sunny beach with gentle waves under a clear blue sky, and on the right, a dramatic coastline with overcast skies and waves crashing against the shore.

From Watts Up With That?

By Anthony Watts

Honestly, I never thought I’d see the day. To quote Mr. FOIA from ClimateGate, “A miracle has occurred.”

Yesterday’s release of the DOE’s A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate is a watershed moment in the ongoing debate over climate policy in America. Why? Because for the first time, a major U.S. government agency—on official letterhead and with a blue-ribbon cast of authors (John Christy, Judith Curry, Steven Koonin, Ross McKitrick, and Roy Spencer)—has published an open challenge to the central claims, data handling, and even the motivations behind mainstream climate science and policy.

This isn’t just another technical report. It is a systematic rebuke of accepted climate “wisdom,” and it does so with unusual clarity, scientific rigor, and (at times) a sense of humor often absent in climate documents. Most importantly, it directly confronts the exaggerated and politicized rhetoric that has dominated headlines for decades.

The Executive Summary from the DOE web page:

This report:

Reviews scientific certainties and uncertainties in how anthropogenic emissions of CO₂ and other GHGs have affected, or will affect, the Nation’s climate, extreme weather events, and metrics of societal well-being.
Assesses the near-term impacts of elevated concentrations of CO₂, including enhanced plant growth and reduced ocean alkalinity.
Evaluates data and projections regarding long-term impacts of elevated concentrations of CO₂, including estimates of future warming.
Finds that claims of increased frequency or intensity of hurricanes, tornadoes, floods, and droughts are not supported by U.S. historical data.
Asserts that CO₂-induced warming appears to be less damaging economically than commonly believed, and that aggressive mitigation policies could prove more detrimental than beneficial.
Finds that U.S. policy actions are expected to have undetectably small direct impacts on the global climate and any effects will emerge only with long delays.

What Makes This Report Unique?

Official Status and Author Independence
Unlike think tank white papers or “dissenting” journal articles, this report comes from within the federal government, under the Trump administration’s DOE. Yet the authors assert full independence—no editorial oversight, no political vetting. It’s rare to see scientists of this caliber (with backgrounds at NASA, IPCC, and major universities) allowed to directly challenge prevailing policy narratives with government resources behind them.
Comprehensive Critique, Not Just a Narrow Rebuttal
Rather than focusing on a single point of controversy, the report systematically evaluates everything from CO2’s physiological role in plant growth, to climate sensitivity estimates, to the track record of climate models, to the real-world impacts (or lack thereof) on extreme weather and U.S. agriculture. Each chapter is loaded with extended quotes from peer-reviewed literature and clear explanations of scientific uncertainty and model error.
Explicit Address of Policy Missteps and Economic Risks
Most uniquely, the report doesn’t stop at “science.” It details the economic costs of climate policy—especially the social cost of carbon modeling games and the virtually undetectable impact U.S. mitigation will have on the global climate. This is a rarely admitted fact, buried in most government assessments but here discussed openly and at length.
Direct Critique of Media, IPCC, and U.S. National Climate Assessments
In one chapter after another, the report highlights the misuse of worst-case scenarios (RCP8.5), the prevalence of “publication bias” in alarming ocean acidification studies, and the outright neglect of positive CO2 impacts like global greening. The report does not hesitate to call out “systemic misuse of scenarios in climate research” and points to specific agencies and news outlets responsible for propagating misleading claims.

My List of the Eight Most Important Findings in the Report

CO2 Is Not a Conventional Pollutant and Has Direct Environmental Benefits
Unlike actual pollutants, CO2 has no toxic effect at ambient levels, is essential for plant life, and has caused global greening—a fact barely acknowledged in IPCC summaries.
“Ocean Acidification” Fears Are Overblown
Oceans are still alkaline, and changes in pH are within natural variability; most ocean life evolved under much lower pH. The report exposes publication bias and lack of reproducibility in many alarming acidification studies. The Great Barrier Reef is currently thriving.
Climate Models Consistently Overestimate Warming
Most climate models run “hot,” overstating recent warming at the surface and in the troposphere. Data-driven climate sensitivity estimates are lower and more constrained than model-based ones, challenging the high ECS values used to justify drastic policy measures.
No Evidence for Increases in Most U.S. Extreme Weather
U.S. historical data shows no long-term upward trend in hurricanes, tornadoes, floods, or droughts. Claims of worsening disasters are unsupported by observations; fire trends are largely due to land management, not climate change.
Sea Level Rise Is Not Accelerating Dangerously
Global sea level has risen about 8 inches since 1900, but regional U.S. sea level trends are dominated by local land movements, not acceleration from climate change. Tide gauges do not show alarming acceleration.
Attribution of Warming to CO2 Is Far Less Certain Than Claimed
Natural variability, incomplete data, and significant model uncertainties make attribution of observed warming and extremes to human CO2 emissions tenuous. Solar variability may be underestimated in mainstream assessments.
The Social Cost of Carbon (SCC) Is Largely Arbitrary
SCC estimates, which drive regulatory costs, are shown to be highly sensitive to model assumptions, with no robust economic basis. The report demonstrates that realistic ECS values and updated economic inputs lead to much lower SCC estimates.
U.S. Emission Reductions Will Have Negligible Impact on Global Climate
Even extreme U.S. policy actions will produce climate changes too small to detect for generations—an inconvenient truth almost never discussed in mainstream policy or media reports.

Here is a Breakdown of How the Report Challenges Mainstream Climate Science

CO2: Pollutant or Plant Food?

The DOE report begins by demolishing the notion that CO2 should be treated as a conventional pollutant, as regulated under the Clean Air Act. It cites OSHA exposure limits (5,000 ppm—orders of magnitude above outdoor levels) and presents robust evidence from plant physiology showing that rising CO2 enhances growth, improves water use efficiency, and has led to the global greening phenomenon observed by satellites.

Notably, the report details how IPCC assessments downplay or omit this global greening effect, despite its direct connection to rising CO2. Even the IPCC’s own Special Report on Land concluded “with high confidence” that greening has occurred, yet this is absent from summary reports intended for policymakers and the public.

Ocean “Acidification”: A Manufactured Crisis?

The report’s treatment of ocean acidification is a case study in scientific skepticism. It points out that “acidification” is a misnomer—oceans remain alkaline, and pH fluctuations are within historic norms. Life in the ocean evolved under a much broader range of pH conditions. More importantly, the DOE authors highlight the growing recognition of “publication bias”: studies with null or minimal impacts from declining pH are difficult to publish, leading to a skewed scientific record.

A meta-analysis cited in the report finds a strong “decline effect” in ocean acidification impacts on fish behavior: early alarming results are rarely replicated by later, larger studies, which usually show negligible impacts. In short, the “crisis” has been grossly exaggerated in the literature and the media.

Model Failure: The Emperor Has No Clothes

The centerpiece of the DOE critique is the performance of global climate models. The report notes that despite decades of effort and billions spent, model projections have failed to narrow the uncertainty in equilibrium climate sensitivity (ECS). In fact, the spread of ECS in the latest (CMIP6) models has grown wider, not narrower, and the majority of models produce too much warming compared to observations—both at the surface and throughout the troposphere.

Crucially, the report provides detailed side-by-side comparisons of model projections versus observed data (see page 33–37). It notes that only models with the lowest ECS values match the actual temperature record since 1979. The majority of models overestimate warming, in some cases by more than a factor of two.

The report also skewers the widespread misuse of “worst-case” emissions scenarios (RCP8.5) in research and media. It cites analysis showing that the vast majority of climate impact papers used RCP8.5 as a business-as-usual baseline, despite the scenario being grossly implausible and far above observed emissions trends.

Attribution and Natural Variability

The report spends several chapters dissecting the uncertainties around attribution—the attempt to link observed warming and extreme events specifically to human GHG emissions. The authors document the wide range of natural variability (including the still-uncertain role of solar variation), and show that statistical “fingerprinting” methods are often inconclusive or circular. In some key cases, model simulations of vertical temperature profiles and the geographic distribution of warming simply fail to match real-world data—a fact not honestly conveyed in mainstream summaries.

The Social Cost of Carbon: An Economic Mirage

One of the most policy-relevant chapters debunks the “social cost of carbon” (SCC) calculations used by regulatory agencies to justify massive economic interventions. The DOE report shows that SCC values are essentially “made up,” highly sensitive to a few subjective assumptions about climate sensitivity, discount rates, and economic damages. When updated with realistic parameters and best-estimate ECS values, the SCC drops dramatically, sometimes to near zero or even negative (i.e., net benefits from CO2 emissions due to agricultural gains).

U.S. Policy: All Pain, No Gain

Perhaps the most striking section (and one likely to cause heartburn in certain policy circles) comes at the end: the scale of the U.S. impact on the global climate. The report quantifies just how little effect even the most aggressive U.S. mitigation policies will have—using the very models and assumptions of mainstream climate science. The answer: “undetectably small” impacts, appearing only after centuries, if at all. This fact is never honestly presented in the typical policy debate.

Of course, the Media is Panning It

Predictably, the release of the DOE report has drawn fire from mainstream outlets and climate advocacy groups. For example, the ever angry and alarmed, The Guardian wrote:

“Climate scientists have condemned the DOE’s new report as ‘dangerous disinformation,’ claiming it was designed to mislead the public about the risks of greenhouse gas emissions and to justify a rollback of U.S. climate policy. Several experts criticized the report for cherry-picking studies and downplaying the consensus on climate risks.”

LOL. Let’s address these lightweight claims, point by point:

Claim: The report is “disinformation” and “cherry-picks” studies.
Pushback: The DOE report is authored by respected scientists with deep experience in climate modeling, attribution, and atmospheric science—many of whom have published widely in peer-reviewed journals. The report is overwhelmingly referenced, including citations from the very IPCC reports it critiques, and in fact spends entire chapters reviewing both sides of contested issues. The presence of extended quotations from mainstream literature, including detailed reviews of opposing arguments, refutes the idea that it is simply “cherry-picking.”

Claim: The report “downplays the consensus” on climate risks.
Pushback: The DOE report does not deny climate change or human influence. It argues, with substantial evidence, that the level of risk is greatly overstated, that models exaggerate sensitivity, and that the costs of mitigation policies are vastly underestimated. It is not “disinformation” to present documented, peer-reviewed evidence that calls into question apocalyptic scenarios—especially when such scenarios are contradicted by the data.

Claim: The report is designed to justify policy rollbacks.
Pushback: The report’s authors explicitly state their independence and reject any suggestion of political vetting or pressure. They also include dissent and debate within the team. The report’s focus is on evidence, not policy prescription. The fact that it challenges established policy is a sign of its intellectual independence, not its bias.

Gavin Schmidt’s “RealClimate” website barely managed a whimper, starting an open thread, saying:

The EPA, along with the “Climate Working Group” of usual suspects (plus Judith Curry and Ross McKitrick) at DOE, have just put out a document for public comment their attempt to rescind the 2009 Endangerment Finding for greenhouse gas emissions.

I got a real laugh out of one of the four comments so far:

Secular Animist says

29 Jul 2025 at 4:35 PM

The proposed rule to rescind the 2009 Endangerment Finding is an ACT OF WAR against the human species by the fossil fuel industry.

LOL, bring it, you anonymous dork.

My Cold Hard Facts Conclusion

The DOE’s A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate stands out as a landmark challenge to the status quo in climate science and policy. It is a detailed, referenced, and balanced review—one that will make uncomfortable reading for those invested in climate alarmism or rigid consensus. It doesn’t offer certainty; it offers scientific humility, transparency, and an honest assessment of the uncertainties and limitations in current climate science.

The real “dangerous disinformation” isn’t in this report—it’s in the repeated failure of the mainstream media and science to confront inconvenient evidence, model errors, and the economic reality of climate policy. It’s long past time for the climate debate to embrace the kind of open, skeptical, and evidence-based assessment represented in this DOE report.

REFERENCES:

DOE Report (Main Document)

DOE, A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate, July 2025 https://www.energy.gov/sites/default/files/2025-07/DOE_Critical_Review_of_Impacts_of_GHG_Emissions_on_the_US_Climate_July_2025.pdf

Key Peer-Reviewed and Official References Used in the DOE Report

1. IPCC Assessment Reports

IPCC Sixth Assessment Report (AR6, 2021)
https://www.ipcc.ch/assessment-report/ar6/
IPCC Fifth Assessment Report (AR5, 2013/2014)
https://www.ipcc.ch/assessment-report/ar5/

2. Climate Model Performance and Sensitivity

Hausfather, Z., et al. (2019). Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters 47(1).
https://doi.org/10.1029/2019GL085378
Scafetta, N. (2021). Testing the CMIP6 GCM simulations versus surface temperature records… Climate 9(11):161.
https://doi.org/10.3390/cli9110161
Sherwood, S. C., et al. (2020). An assessment of Earth’s climate sensitivity using multiple lines of evidence. Reviews of Geophysics, 58(4).
https://doi.org/10.1029/2019rg000678
Lewis, N. (2023). Objectively combining climate sensitivity evidence. Climate Dynamics 61, 3155–3163.
https://doi.org/10.1007/s00382-022-06398-8
Pielke Jr., R., & Ritchie, J. (2020). Systemic Misuse of Scenarios in Climate Research and Assessment. SSRN.
https://ssrn.com/abstract=3581777
Hausfather, Z. & Peters, G. P. (2020). Emissions – the ‘business as usual’ story is misleading. Nature.
https://www.nature.com/articles/d41586-020-00177-3

3. CO₂, Global Greening, and Fertilization

Zhu, Z., et al. (2016). Greening of the Earth and its drivers. Nature Climate Change, 6, 791–795.
https://www.nature.com/articles/nclimate3004
Chen, C., et al. (2019). China and India lead in greening of the world through land-use management. Nature Sustainability 2, 122–129.
https://www.nature.com/articles/s41893-019-0220-7
Keenan, T. F., et al. (2023). A constraint on historic growth in global photosynthesis due to rising CO₂. Nature Climate Change 13, 1376-1381.
https://doi.org/10.1038/s41558-023-01867-2
Haverd, V., et al. (2020). Higher than expected CO₂ fertilization inferred from leaf to global observations. Global Change Biology 26, 2390–2402.
https://doi.org/10.1111/gcb.14950

4. Ocean “Acidification” and Coral Reefs

Clements, J. C., et al. (2022). Meta-analysis reveals an extreme ‘decline effect’ in the impacts of ocean acidification on fish behavior. PLOS Biology, 20(2), e3001511.
https://doi.org/10.1371/journal.pbio.3001511
Browman, H. I. (2016). Applying organized scepticism to ocean acidification research. ICES Journal of Marine Science, 73(3), 529–536.
https://doi.org/10.1093/icesjms/fsw010
Australian Institute of Marine Science. (2022). Continued coral recovery leads to 36-year highs across two-thirds of the Great Barrier Reef.
https://www.aims.gov.au/sites/default/files/2022-08/AIMS_LTMP_Report_on%20GBR_coral_status_2021_2022_040822F3.pdf

5. Extreme Weather Data

NOAA National Centers for Environmental Information (NCEI) U.S. Billion-Dollar Weather and Climate Disasters:
https://www.ncdc.noaa.gov/billions/
Rutgers University Global Snow Lab:
https://climate.rutgers.edu/snowcover/

6. Solar Influence and Natural Variability

Connolly, R., et al. (2021). How much has the Sun influenced Northern Hemisphere temperature trends? An ongoing debate. Research in Astronomy and Astrophysics 21(6).
https://iopscience.iop.org/article/10.1088/1674-4527/21/6/131

7. Social Cost of Carbon and Economic Analyses

Dayaratna, K., et al. (2017). Empirically-Constrained Climate Sensitivity and the Social Cost of Carbon. Climate Change Economics.
https://doi.org/10.1142/S2010007817500063
Dayaratna, K., McKitrick, R., Michaels, P.J. (2020). Climate Sensitivity, Agricultural Productivity and the Social Cost of Carbon in FUND. Environmental Economics and Policy Studies.
https://doi.org/10.1007/s10018-020-00263-w

8. Emissions Scenarios Critiques

Burgess, M., et al. (2021). Plausible 2005-2050 emissions scenarios project between 2 and 3 degrees C of warming by 2100. Environmental Research Letters 16 014016.
https://iopscience.iop.org/article/10.1088/1748-9326/abcdd2/meta

Official & U.S. Government Data

NOAA Global Monitoring Laboratory CO₂ Trends:
https://gml.noaa.gov/ccgg/trends/
U.S. EPA Criteria Air Pollutants:
https://www.epa.gov/criteria-air-pollutants
U.S. Occupational Safety and Health Administration (OSHA) Carbon Dioxide:
https://www.osha.gov/chemicaldata/183

Additional Useful Reports for Context

Pielke Jr., R., Burgess, M. G., & Ritchie, J. (2022). Plausible 2005–2050 emissions scenarios… Environmental Research Letters 17 024027.
https://iopscience.iop.org/article/10.1088/1748-9326/ac4ebf/pdf

Oh noes! WMO report documents spiralling weather and climate impacts

WMO report documents spiralling weather and climate impacts
The clear signs of human-induced climate change reached new heights in 2024, with some of the consequences being irreversible over hundreds if not thousands of years, according to a new report from the World Meteorological Organization (WMO), which also underlined the massive economic and social upheavals from extreme weather.

A dramatic montage depicting various extreme weather events: a lightning storm, volcanic eruption with flowing lava, wildfire, and a tornado. The contrasting elements emphasize the intensity and danger of climate change impacts.

From Watts Up With That?

By Anthony Watts

We somehow missed this, it is entertaining – Anthony

WMO report documents spiralling weather and climate impacts

The clear signs of human-induced climate change reached new heights in 2024, with some of the consequences being irreversible over hundreds if not thousands of years, according to a new report from the World Meteorological Organization (WMO), which also underlined the massive economic and social upheavals from extreme weather.

Key messages

Key climate change indicators again reach record levels
Long-term warming (averaged over decades) remains below 1.5°C
Sea-level rise and ocean warming irreversible for hundreds of years
Record greenhouse gas concentrations combined with El Niño and other factors to drive 2024 record heat
Early warnings and climate services are vital to protect communities and economies

A split image depicting contrasting environmental conditions: on one side, a serene lake with lily pads and mountains in the background; on the other side, a dry, cracked earth surface representing drought and climate change impacts. — Canva

WMO’s State of the Global Climate report confirmed that 2024 was likely the first calendar year to be more than 1.5°C above the pre-industrial era, with a global mean near-surface temperature of 1.55 ± 0.13 °C above the 1850-1900 average. This is the warmest year in the 175-year observational record.

WMO’s flagship report showed that:

Atmospheric concentration of carbon dioxide are at the highest levels in the last 800,000 years.
Globally each of the past ten years were individually the ten warmest years on record.
Each of the past eight years has set a new record for ocean heat content.
The 18 lowest Arctic sea-ice extents on record were all in the past 18 years.
The three lowest Antarctic ice extents were in the past three years.
The largest three-year loss of glacier mass on record occurred in the past three years.
The rate of sea level rise has doubled since satellite measurements began.

“Our planet is issuing more distress signals — but this report shows that limiting long-term global temperature rise to 1.5 degrees Celsius is still possible. Leaders must step up to make it happen — seizing the benefits of cheap, clean renewables for their people and economies – – with new National climate plans due this year, ” said United Nations Secretary-General António Guterres.

“While a single year above 1.5 °C of warming does not indicate that the long-term temperature goals of the Paris Agreement are out of reach, it is a wake-up call that we are increasing the risks to our lives, economies and to the planet,” said WMO Secretary-General Celeste Saulo.

Line graph showing global mean temperature anomalies from 1850 to 2024, illustrating the difference from the 1850-1900 average, with data from multiple sources.

The report said that long-term global warming is currently estimated to be between 1.34 and 1.41 °C compared to the 1850-1900 baseline based on a range of methods – although it noted the uncertainty ranges in global temperature statistics.

A WMO team of international experts is examining this further in order to ensure consistent, reliable tracking of long-term global temperature changes to be aligned with the Intergovernmental Panel on Climate Change (IPCC).

Regardless of the methodology used, every fraction of a degree of warming matters and increases risks and costs to society.

The record global temperatures seen in 2023 and broken in 2024 were mainly due to the ongoing rise in greenhouse gas emissions, coupled with a shift from a cooling La Niña to warming El Niño event. Several other factors may have contributed to the unexpectedly unusual temperature jumps, including changes in the solar cycle, a massive volcanic eruption and a decrease in cooling aerosols, according to the report.

Temperatures are just a small part of a much bigger picture.

“Data for 2024 show that our oceans continued to warm, and sea levels continued to rise. The frozen parts of Earth’s surface, known as the cryosphere, are melting at an alarming rate: glaciers continue to retreat, and Antarctic sea ice reached its second-lowest extent ever recorded. Meanwhile, extreme weather continues to have devastating consequences around the world,” said Celeste Saulo.

Tropical cyclones, floods, droughts, and other hazards in 2024 led to the highest number of new displacements recorded for the past 16 years, contributed to worsening food crises, and caused massive economic losses.

“In response, WMO and the global community are intensifying efforts to strengthen early warning systems and climate services to help decision-makers and society at large be more resilient to extreme weather and climate. We are making progress but need to go further and need to go faster. Only half of all countries worldwide have adequate early warning systems. This must change,” said Celeste Saulo.

Investment in weather, water and climate services is more important than ever to meet the challenges and build safer, more resilient communities, she stressed.

The report is based on scientific contributions from National Meteorological and Hydrological Services, WMO Regional Climate Centres, UN partners and dozens of experts. It includes sidebars on monitoring global temperature for the Paris Agreement and understanding the temperature anomalies in 2023 and 2024. It includes supplements on climate services and on extreme weather.

It is one of a suite of WMO scientific reports which seek to inform decision-making. It was published ahead of World Meteorological Day on 23 March, World Water Day on 22 March and World Glaciers Day on 21 March.

Bar graph showing estimates of current global warming with values for 2024 ranging from 1.34°C to 1.41°C, indicating that temperatures remain below 1.5°C.

Three methods for establishing an up-to-date estimate of current global warming as of 2024, compared with the IPCC AR6 method, which uses averages over the previous 10 years and is representative of warming to 2019. The best estimate resulting from each method is shown as a dark vertical line, and the uncertainty range is shown by the shaded area.

Key Indicators

Atmospheric Carbon Dioxide

Atmospheric concentration of carbon dioxide, as well as methane and nitrous oxide, are at the highest levels in the last 800,000 years.

Carbon dioxide concentrations in 2023 (the last year for which consolidated global annual figures are available) were 420.0 ± 0.1 parts per million (ppm), 2.3 ppm more than 2022 and 151% of the pre-industrial level (in 1750). 420 ppm corresponds to 3,276 Gt – or 3.276 trillion tonnes of CO₂ in the atmosphere.

Real-time data from specific locations show that levels of these three main greenhouse gases continued to increase in 2024. Carbon dioxide remains in the atmosphere for generations, trapping heat.

Global Mean Near-surface Temperature

In addition to 2024 setting a new record, each of the past ten years, 2015-2024, were individually the ten warmest years on record.

The record temperature in 2024 was boosted by a strong El Niño which peaked at the start of the year. In every month between June 2023 and December 2024, monthly average global temperatures exceeded all monthly records prior to 2023.

Record levels of greenhouse gases were the primary driver, with the shift to El Niño playing a lesser role.

Ocean Heat Content

Around 90% of the energy trapped by greenhouse gases in the Earth system is stored in the ocean.

In 2024, ocean heat content reached its highest level in the 65-year observational record. Each of the past eight years has set a new record. The rate of ocean warming over the past two decades, 2005-2024, is more than twice that in the period 1960-2005.

Ocean warming leads to degradation of marine ecosystems, biodiversity loss, and reduction of the ocean carbon sink. It fuels tropical storms and contributes to sea-level rise. It is irreversible on centennial to millennial time scales. Climate projections show that ocean warming will continue for at least the rest of the 21st century, even for low carbon emission scenarios.

Acidification of the ocean surface is continuing, as shown by the steady decrease of global average ocean surface pH. The most intense regional decreases are in the Indian Ocean, the Southern Ocean, the eastern equatorial Pacific Ocean, the northern tropical Pacific, and some regions in the Atlantic Ocean.

The effects of ocean acidification on habitat area, biodiversity and ecosystems have already been clearly observed, and food production from shellfish aquaculture and fisheries has been hit as have coral reefs.

Projections show that ocean acidification will continue to increase in the 21st century, at rates dependent on future emissions. Changes in deep-ocean pH are irreversible on centennial to millennial time scales.

Line graph depicting global ocean heat content from 1960 to 2024, showing a significant upward trend, with shaded areas representing uncertainty ranges for different studies.

Annual global ocean heat content down to 2000 m depth for the period 1960–2024, in zettajoules (1021 J). The shaded area indicates the 2-sigma uncertainty range on each estimate.

Global Mean Sea Level

In 2024, global mean sea level was the highest since the start of the satellite record in 1993 and the rate of increase from 2015-2024 was double that from 1993–2002, increasing from 2.1 mm per year to 4.7 mm per year.

Sea level rise has cascading damaging impacts on coastal ecosystems and infrastructure, with further impacts from flooding and saltwater contamination of groundwater.

Glacier Mass Balance

The period 2022-2024 represents the most negative three-year glacier mass balance on record. Seven of the ten most negative mass balance years since 1950 have occurred since 2016.

Exceptionally negative mass balances were experienced in Norway, Sweden, Svalbard, and the tropical Andes.

Glacier retreat increases short-term hazards, harms economies and ecosystems and long-term water security.

Glacier cumulative mass balance 1950-2024

Line graph showing annual mountain glacier cumulative mass balance from 1950 to 2024, indicating a significant decline over the years.

Sea-ice Extent

The 18 lowest Arctic sea-ice minimum extents in the satellite record all occurred in the past 18 years. The annual minimum and maximum of Antarctic sea-ice extent were each the 2nd lowest in the observed record from 1979.

The minimum daily extent of sea-ice in the Arctic in 2024 was 4.28 million km2, the 7th lowest extent in the 46-year satellite record. In Antarctica, the minimum daily extent tied for the 2nd lowest minimum in the satellite era and marked the 3rd consecutive year that minimum Antarctic sea-ice extent dropped below 2 million km2. These are the three lowest Antarctic ice minima in the satellite record.

Extreme events and impacts

Extreme weather events in 2024 led to the highest number of new annual displacements since 2008, and destroyed homes, critical infrastructure, forests, farmland and biodiversity.

The compounded effect of various shocks, such as intensifying conflict, drought and high domestic food prices drove worsening food crises in 18 countries globally by mid-2024.

Tropical cyclones were responsible for many of the highest-impact events of 2024. These included Typhoon Yagi in Viet Nam, the Philippines and southern China.

In the United States, Hurricanes Helene and Milton in October both made landfall on the west coast of Florida as major hurricanes, with economic losses of tens of billions of dollars. Over 200 deaths were associated with the exceptional rainfall and flooding from Helene, the most in a mainland United States hurricane since Katrina in 2005.

Tropical Cyclone Chido caused casualties and economic losses in the French Indian Ocean Island of Mayotte, Mozambique and Malawi. It displaced around 100,000 people in Mozambique.

Climate Fact-Check June 2025

Scientifically debunking claims about heatwaves, hurricanes, extreme weather, ocean acidification, & food shortages.

From ClimateRealism

By Steve Milloy

Guest Post by: The Competitive Enterprise Institute, The Heartland Institute, the Energy & Environmental Legal Institute, the Committee for a Constructive Tomorrow, and the International Climate Science Coalition, and Truth in Energy and Climate.

Editor’s note: This summary serves as a fact check on the top false claims made about climate change by the media in June 2025.

Scientifically debunking claims about heatwaves, hurricanes, extreme weather, ocean acidification, & food shortages.

Links: MSNBC article, *Nature* link, NOAA retiring the metric, 2024 study.

Links: *The Seattle Times* article, Duwamish river flooding, sea level rise in Seattle.

Links: *The Hill* article, study, IPCC, Great Barrier Reef extent.

Links: Facebook post, very hot days in Florida data, NOAA data.

Links: CNN article, EPA data, National Climate Assessment data, EPA heat index.

Links: TIME story, jet stream research, declining circulation patterns.

Until next month, enjoy these and other great climate fact checks at:

ClimateRealism.com

ClimateDepot.com

Wattsupwiththat.com

Originally published at Junkscience.com, reposted with permission.

Stop Lying, The Guardian, the World’s Oceans Aren’t Becoming Dangerously Acidic

The U.K.’s The Guardian ran an article claiming that the world’s oceans have surpassed a critical tipping point in acidity threatening sea life. This is false. The pH content of the world’s oceans varies by time and place throughout the day, rising and falling modestly, but the average pH content remains far from acidic and there is no evidence crustaceans or other types of shellfish are being threatened by the sea water becoming acidic.

From ClimateRealism

By H. Sterling Burnett

The U.K.’s The Guardian ran an article claiming that the world’s oceans have surpassed a critical tipping point in acidity threatening sea life. This is false. The pH content of the world’s oceans varies by time and place throughout the day, rising and falling modestly, but the average pH content remains far from acidic and there is no evidence crustaceans or other types of shellfish are being threatened by the sea water becoming acidic.

Lisa Bachelor, the writer of The Guardian’s article, “‘Ticking timebomb’: sea acidity has reached critical levels, threatening entire ecosystems – study,” says:

The world’s oceans are in worse health than realized, scientists have said today, as they warn that a key measurement shows we are “running out of time” to protect marine ecosystems.

Ocean acidification, often called the “evil twin” of the climate crisis, is caused when carbon dioxide is rapidly absorbed by the ocean, where it reacts with water molecules leading to a fall in the pH level of the seawater. It damages coral reefs and other ocean habitats and, in extreme cases, can dissolve the shells of marine creatures.

Bachelor’s story is based upon a study which claims that ocean acidity has breached a “planetary boundary,” the seventh of nine such milestones or boundaries to be breached, threatening to cause permanent damage to the planet’s health.

The study looked at ice core records and studies of marine life, run through algorithms of complex computer models to assess the past 150 years, concluding the ocean acidification boundary had been breached, with the world facing a “ticking timebomb,” of sea life destruction.

This study’s findings are driven by woefully flawed computer models, a limited time horizon and understanding of long-term history, and lack a basis in real world data. As such it and The Guardian’s dire warnings based on it, are unjustified.

Model outputs are only as good as the assumptions, data, and our understandings of the feedbacks and systems built into them. Even as our knowledge improves, our understanding of the oceans and the interactions of its various currents, systems, inputs, and outputs remain limited, thus the assumptions built into the models are weak and uncertain. As discussed at Climate Realism, here, here, and here, for example, the climate model outputs fail to match reality.

Concerning the limited time scale of this paper’s analysis, 150 years is a blip in the history of the Earth and its oceans. Coral reefs and shellfish have existed, thrived and evolved over tens of millions to hundreds of millions of years, through periods of both more alkaline and more acidic oceans. Based on current data, there is no reason to believe that recent changes in ocean pH threatens a “timebomb,” or apocalypse for shellfish and other sea life, at least not if one cares about solid evidence as opposed to model outputs.

There are, in fact, no scientifically established “planetary boundaries,” or “tipping points.” Rather such claims are political in nature, meant to drive political action (and likely increased funding) on behalf of the concerns of select groups of scientists. If the research of a select group of scientists are to be believed, the Earth has already surpassed seven of the nine purported boundaries – yet, data on extreme weather shows no worsening of hurricanes, tornados, wildfires, heat waves, drought, temperature or weather related deaths, or long-term coral or shellfish decline (at least, for the latter, no decline not tied to pollution and overharvesting). As such, one must wonder what dangers surpassing the supposed boundaries pose if exceeding them results in no identifiable harm that can be linked to the breach?

Which brings us to the crux of the study’s and The Guardian’s assertions that oceans are becoming dangerously acidic. Climate Realism has rebutted previous mainstream media stories claiming human carbon dioxide emissions were causing the oceans to become more acidic on 10 previous occasions. What the evidence shows is ocean pH varies significantly across the globe, with levels in tropical regions being more than twice as high as those in polar and that marine life has evolutionarily adapted to changes in pH.

In addition, the U.S. Environmental Protection Agency acknowledges that sea water has a normal pH of 8.1 and nowhere across the ocean is anywhere close to 7.0 or below. “Although climate models suggest the oceans’ surface pH may have dropped from pH 8.2 to 8.1 since 1750, that change was never actually measured, rather the pH drop is merely a modeled conjecture,” as Climate at a Glance: Ocean Acidification explains. The EPA provides a helpful graphic by way of comparison. (see the graphic, below)

Comparison of the pH of common substances. Data source: U.S. Environmental Protection AgencFigure 1. Comparison of the pH of common substances. Source: U.S. Environmental Protection Agency, “Measuring Acid Rain,” epa.gov, last accessed August 12, 2021, https://www.epa.gov/acidrain/what-acid-rainy

To conclude, acidic oceans make for a good scare story, raising the specter of mountains of dead and disintegrating sea life and perhaps bathers and surfers dissolving before horrified beachgoers’ eyes, but neither imaginative image has any relation to reality. We don’t know for sure whether ocean pH has declined over time during the recent period of climate change, but we do know that more than halfway to a doubling of atmospheric CO₂ concentrations above pre-industrial levels, average ocean pH levels are well above the neutral 7 mark, and if they’ve declined at all, it has been by a barely measurable amount. As a result, contra The Guardian’s headline, there is no identifiable “ticking timebomb” threatening ocean ecosystems.

pHony Alarmism

For a while now scientists have been raising the alarm about the effect of increasing atmospheric CO2 on the pH of the ocean. pH is a measure of whether something is acidic (pH below 7), alkaline, also called basic (pH above 7) or neutral (pH of 7). The ocean is slightly alkaline, and rainwater is slightly acidic. Here are some examples.

From Watts Up With That?

Guest Post by Willis Eschenbach

What’s happening is that the ocean is moving slightly toward neutral. However, “ocean neutralization” doesn’t sound alarming enough, so they’re falsely labeling it “ocean acidification”. Here are some quotes.

“Generally, shelled animals—including mussels, clams, urchins and starfish—are going to have trouble building their shells in more acidic water, just like the corals. Mussels and oysters are expected to grow less shell by 25 percent and 10 percent respectively by the end of the century… oyster larvae fail to even begin growing their shells.”

Ocean Acidification, Smithsonian Museum

“After exposing them to a range of acidity levels, UC Davis scientists found that under high CO₂, or more acidic, conditions, the foraminifera had trouble building their shells and making spines, an important feature of their shells. They also showed signs of physiological stress, reducing their metabolism and slowing their respiration to undetectable levels.”

Tiny Shells Indicate Big Changes to Global Carbon Cycle, UC Davis

“Like a piece of chalk dissolving in vinegar, marine life with hard shells is in danger of being dissolved by increasing acidity in the oceans. Ocean acidity is rising as sea water absorbs more carbon dioxide released into the atmosphere from power plants and automobiles. The higher acidity threatens marine life, including corals and shellfish, which may become extinct later this century from the chemical effects of carbon dioxide, even if the planet warms less than expected.”

Regardless of global warming, rising CO2 levels threaten marine life, University of Illinois

YIKES! EVERYONE PANIC!

I got to thinking about this, and I thought … wait a minute. There have been hard-shelled animals in the ocean since the end of the Cambrian Explosion about 485 million years ago. Say what?

Now, there’s a new study out in Science Magazine (paywalled, of course) that contains estimates of both atmospheric CO2 and oceanic pH since 485 million years ago. 485 million years ago is roughly the end of what’s called the “Cambrian Explosion Of Life”, a time when a huge number of life forms emerged on the earth.

Here’s their estimate of CO2 levels since the Cambrian Explosion.

*Figure 1. Title says it all. I’ve added the modern increase at the recent end of the graph.*

You might ask, “If the study is paywalled, how did you get the data”. Well, their Supplementary Online Information isn’t paywalled, and it contains this graphic.

*Figure 2. Panel B, Figure S10, op. cit.*

Note that the CO2 levels are shown on a log scale to visually minimize the size of the actual changes … but I digress. Sadly, they didn’t include a table of the data. So I had to digitize it. Takes a while, but I’m a patient man.

*Figure 3. Digitization of the graph shown in Figure 2.*

Looking back at Figure 1, the most remarkable features are the large and rapid drop in CO2 levels starting around 470 million years before the present (Ma BP), and the somewhat slower but almost as large rise starting around 430 Ma BP.

The 470 Ma BP drop is generally attributed to enhanced silicate weathering of the mountains by early land plants, and reduced volcanic CO₂ input. And the increase is generally attributed to reduced mountain weathering due to glaciation, along with an increase in volcanic CO₂ emission. Are those actually the causes? Unknown. The Late Ordovician glaciation only covered about 13%-14% of the land area, compared to about 25% of the land area during the most recent glaciation. So that part of the explanation seems unlikely, but what do I know?

In any case, the study also has a graph of the pH of the ocean over the same period of time. How accurate is it? Also, unknown. Presumably, however, it’s currently our best estimate of the variations of oceanic pH over 485 million years. Again, I digitized the data. Here’s that graph.

Now, there are several noteworthy points in this graph. First, at no time in the past 485 million years has the ocean been acidic. It has always been alkaline (basic), with a pH always greater than 7 (neutral pH).

Second, over that entire time, there has been a huge variety and profusion of shelled animals living in the ocean, apparently unbothered by the variations in alkalinity.

Third, in the upper right of Figure 4 is a tiny vertical line with horizontal “whiskers” at the top and bottom. It shows the modern change in pH since 1850, the change that has all the megabrains calling the Climate 911 hotline to report an emergency … color me unimpressed. We’ve run the oceanic pH experiment over the last half billion years. Shelled creatures didn’t disappear.

TL;DR version? Life has flourished, both above and below the surface of the sea, through periods when atmospheric CO2 has varied up to almost ten times the current level. As a result, the myriad of alarmist claims that increasing CO2 is some kind of death sentence for life either on the land or in the ocean all run aground on a reef of hard facts.

Don’t believe me about pH and creatures with shells? Ask the chambered nautilus, a lovely cephalopod with a hard shell. I once saw a school of them while scuba diving, and I have the shell of one that I picked up years ago on a beach on one of the outer islands in Fiji.

It’s one of the most ancient creatures in the sea, and it has existed in a virtually unchanged form for half a billion years … funny how the changes in oceanic pH didn’t disturb it one bit.

Best to all on a sunny afternoon,

Yeah, you’ve heard it before … when you comment, please quote the exact words you are discussing. I can defend my words; I choose them carefully. I cannot defend your understanding of my words.

My Other Analyses Of the Ocean Neutralization Question:

pH Sampling Density 2014-12-30

A recent post by Anthony Watts highlighted a curious fact. This is that records of some two and a half million oceanic pH samples existed, but weren’t used in testimony before Congress about ocean pH. The post was accompanied by a graph which purported to show a historical variation in ocean…

The Reef Abides 2011-10-25

I love the coral reefs of the planet. In my childhood on a dusty cattle ranch in the Western US, I decorated my mental imaginarium of the world with images of unbelievably colored reefs below white sand beaches, with impossibly shaped fish and strange, brilliant plants. But when I finally…

The Electric Oceanic Acid Test 2010-06-19

I’m a long-time ocean devotee. I’ve spent a good chunk of my life on and under the ocean as a commercial and sport fisherman, a surfer, a blue-water sailor, and a commercial and sport diver. So I’m concerned that the new poster-boy of alarmism these days is sea-water “acidification” from…

A Neutral View of Oceanic pH 2015-01-02

Following up on my previous investigations into the oceanic pH dataset, I’ve taken a deeper look at what the 2.5 million pH data points from the oceanographic data can tell us. Let me start with an overview of oceanic pH (the measure of alkalinity/acidity, with neutral being a pH of…

The Reef Abides … Or Not 2014-07-06

I’ve written a few times on the question of one of my favorite hangouts on the planet, underwater tropical coral reefs. Don’t know if you’ve ever been down to one, but they are a fairyland of delights, full of hosts of strange and mysterious creatures. I’ve seen them far from…

The Ocean Is Not Getting Acidified 2011-12-27

There’s an interesting study out on the natural pH changes in the ocean. I discussed some of these pH changes a year ago in my post “The Electric Oceanic Acid Test“. Before getting to the new study, let me say a couple of things about pH. The pH scale measures…

Carbon And Carbonate 2016-01-30

I’ve spent a good chunk of my life around, on, and under the ocean. I worked seasonally for many years as a commercial fisherman off of the western coast of the US. I’ve frozen off my begonias setting nets in driving sleet up in the Bering Sea. I’m also a …

The Solution To Dissolution 2020-01-31

The British tabloid “The Guardian” has a new scare story about what is wrongly called “ocean acidification”. It opens as follows: Sounds like the end of times, right? So let me start with a simple fact. The ocean is NOT acidic. Nor will it ever become acidic, except in a few isolated locations. It i…

Dungeness Crabs Redux 2020-02-02

Well, after my last post, The Solution To Dissolution, I thought I was done with the Dungeness crab question. And I was happy to be done with those chilly crustaceans. Writing that post brought back memories of how cold the fishery is. I remember leaving out from Eureka harbor at the north end of Ca…

The Voice Of The Lobster 2020-02-14

Over in the Tweetiverse, someone was all boo-hoo about the eeevil effects of “climate change” that he claimed had “already occurred”. He referenced a publication from a once-noble organization that sadly has drunk the “CLIMATE EMERGENCY” koolaid, National Geographic. So I read it, and the only thing…

The Hill Pushes Discredited Ocean Acidity Scares

Coral cover is breaking records, real world data proves ocean life loves CO2, but none of this impedes a never-ending drip feed of ocean acidification scares.

From Watts Up With That?

Essay by Eric Worrall

Coral cover is breaking records, real world data proves ocean life loves CO2, but none of this impedes a never-ending drip feed of ocean acidification scares.

‘Ticking time bomb’: Ocean acidity crosses vital threshold, study finds

BY SAUL ELBEIN – 06/09/25 11:24 AM ET

The deep oceans have crossed a crucial boundary that threatens their ability to provide the surface with food and oxygen, a new study finds.

Nearly two-thirds of the ocean below 200 meters, or 656 feet, as well as nearly half of that above, have breached “safe” levels of acidity, according to findings published on Monday in Global Change Biology.

The fall in ocean pH is “a ticking time bomb for marine ecosystems and coastal economies,” Steve Widdicombe, director of science at the United Kingdom’s Plymouth Marine Laboratory (PML), said in a statement.

The study was funded in part by the National Oceanographic and Atmospheric Administration (NOAA), a federal agency that has been targeted for steep cuts by the Trump White House, in large part because of its role in investigating climate change.

…Read more:

https://thehill.com/policy/equilibrium-sustainability/5340239-ocean-acidity-study-climate-change-carbon/

The referenced study;

Ocean Acidification: Another Planetary Boundary Crossed

Helen S. Findlay, Richard A. Feely, Li-Qing Jiang, Greg Pelletier, Nina Bednaršek

First published: 09 June 2025

Funding: This work was supported by European Space Agency, AO/1-10757/21/I-DT. Natural Environment Research Council, NE/X006271/1. NOAA’s Global Ocean Monitoring and Observing and Ocean Acidification Programs, GOMO Fund Reference Number 100018302 and OAP NRDD. Slovene Research Agency, N1-0359. Climate Program Office, NA19NES4320002, NA210AR4310251.

ABSTRACT

Ocean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre-industrial aragonite saturation state, state-of-the-art data-model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200 m) had crossed that boundary, compared to over 40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre-industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean.

Read more:

https://onlinelibrary.wiley.com/doi/10.1111/gcb.70238

The ocean acidification “boundary” is based on Aragonite saturation. Aragonite is a form of calcium carbonate. Marine animals use Calcium Carbonate to form shells and coral structures. The theory is if Aragonite saturate drops below one (biased towards dissolution), shellfish and corals will find it difficult to build the calcium carbonate structures they depend on for survival.

Of course, determining habitable Argonite saturation levels is complicated by substantial natural variability.

… Ocean Ω conditions vary significantly across the globe, with levels in tropical regions being more than twice as high as those in polar regions (Feely et al. 2023; Jiang et al. 2015). These regional and seasonal gradients exists due to temperature-driven CO₂ solubility, enabling colder high-latitude waters to store more CO₂, along with other factors including circulation of carbon away from the surface into deeper waters, mineral inputs from land and freshwater dilution (Jiang et al. 2019; Orr et al. 2005). Marine life is exposed to such regionally varying gradients to which it has evolutionarily adapted (Vargas et al. 2022), resulting in a wide variability of observed responses to OA found in laboratory experiments. However, the envelope of the overall conditions experienced by organisms is also changing due to OA, which can make scaling up from single-species experiments to ecosystem predictions more complicated. This is particularly true when we consider the other challenges of scaling, including incubation effects, lack of natural variability and lack of adaptation and/or acclimation.

…

Aragonite saturation state (Ω_Arag) has emerged as a key indicator for OA, reflecting the precipitation/dissolution tendencies of CaCO₃, as well as its association with marine calcifiers. Consequently, the global mean surface Ω_Arag was chosen as the OA indicator in the planetary boundary assessments (Rockström et al. 2009). The boundary was set at 80% of the pre-industrial Ω_Arag value, that is, a 20% reduction from the pre-industrial surface ocean average. This level was chosen based on two criteria: first to keep high-latitude surface waters above Ω_Arag undersaturation; and second, to ensure adequate conditions for most warm-water coral reef systems (Rockström et al. 2009). …Read more: same link as above

Given the immense natural variability, and high genetic mobility of shellfish and corals, many of which reproduce by emitting vast numbers of microscopic larvae, setting the boundary condition at 80% of pre-industrial looks suspiciously like a guess.

Is there a way can we test this 80% boundary?

The solution of course, is to look at how fish and shelled creatures living in extreme environments cope with acidification. And there are few places more extreme than “champagne reefs”, patches of ocean where a constant source of volcanic gas keeps sea water supersaturated with CO2, well beyond anything we could ever achieve with anthropogenic emissions.

The fishes and the coral live happily in the CO2 bubble plume

Evidence trumps guesswork. Given proof that fish and shelled organisms can thrive in the most extraordinary ocean CO2 levels, and the likelihood many of those organisms have genetically compatible relatives which live outside natural CO2 saturated regions, perhaps it is time to revise that 80% boundary.

Tag: Ocean Acidification

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Key Indicators

Atmospheric Carbon Dioxide

Global Mean Near-surface Temperature

Ocean Heat Content

Ocean Acidification

Global Mean Sea Level

Glacier Mass Balance

Glacier cumulative mass balance 1950-2024

Sea-ice Extent

Extreme events and impacts

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Climate Fact-Check June 2025

Guest Post by: The Competitive Enterprise Institute, The Heartland Institute, the Energy & Environmental Legal Institute, the Committee for a Constructive Tomorrow, and the International Climate Science Coalition, and Truth in Energy and Climate.

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Stop Lying, The Guardian, the World’s Oceans Aren’t Becoming Dangerously Acidic

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pHony Alarmism

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