Rebuttal to: ‘2023 Marine Heatwaves Unprecedented and Potentially Signal a Climate Tipping Point’

Another day, another groaner of a climate alarmist press release—this time from the American Association for the Advancement of Science (AAAS), touting a new study that claims the 2023 marine heatwaves were “unprecedented” and may “signal a climate tipping point” posted at EurekAlert, July 24^th,  2025.

The press release: 2023 marine heatwaves unprecedented and potentially signal a climate tipping point

The breathless tone is familiar, and the underlying logic is seriously flawed. But hey, if we scare people into action, we just might save the planet.

Let’s unpack this claim using a simple but often overlooked principle: context matters. Particularly in climate, which has cycles that span millennia, not just decades.

The foundational flaw in this study is its timescale. The research relies on satellite data beginning in 1982. That gives us about 40 years of observational history, which is virtually nothing in terms of Earth’s climate system. Prior to satellite coverage, comprehensive, high-resolution global measurements of sea surface temperatures simply didn’t exist. Claims of “unprecedented” events must be framed within that very limited context. As I’ve said before, declaring a “record” based on such a short window is like calling a coin flip streak a “trend” after four tosses.

Ocean temperatures fluctuate naturally over decadal, centennial, and even millennial scales. Our current observational capacity doesn’t cover even half of one oceanic oscillation cycle, such as the Pacific Decadal Oscillation (PDO), which paleoclimatology suggests runs as long as 50-70 years. To suggest a climate “tipping point” based on this short dataset is not just premature—it’s scientifically irresponsible.

The study makes much of the marine heatwaves’ “extreme” scale and persistence, yet it also quietly admits the 2023 heat spikes were linked to a strong El Niño. This is a naturally recurring phenomenon, not a man-made one. El Niño has been driving global climate variability for thousands of years, influencing ocean currents, sea surface temperatures, and atmospheric patterns.

The Tropical Eastern Pacific, one of the hottest zones in the 2023 event, is historically the epicenter of El Niño conditions. It should surprise no one that temperatures peaked there. What’s odd is the leap from observing a known, cyclical pattern to proclaiming it a new climate threshold.

The modeling mirage is strong with this one. Dong et al. used ECCO2 (Estimating the Circulation and Climate of the Ocean – Phase II), a high-resolution ocean model that ingests satellite data to reconstruct conditions like mixed-layer heat budgets. While ECCO2 is a valuable scientific tool, let’s not forget: models are not measurements. They are educated guesses constrained by initial assumptions and historical tuning.

All models are simplifications, and when dealing with something as complex as ocean-atmosphere interactions, even a small error can yield a wildly different output. Yet here, model outputs are used not just to analyze the past but to hint at an ominous future—a future where every warm patch of seawater is a harbinger of ecological doom.

The press release tries to go for the jugular by suggesting that these marine heatwaves might “portend an emerging climate tipping point”. That’s a phrase straight from the climate playbook of fear, designed to bypass critical thinking and stampede policymakers into hasty action. Even the photo supplied with the press release was chosen to look “hot” and drive fear. Nowhere in the abstract or methods is there clear empirical evidence linking this event to irreversible climate shifts. It’s pure conjecture, wrapped in technical jargon and served up with a greasy side of urgency.

According to the press release, the authors cite “region-specific drivers” for each major marine heatwave. In the North Atlantic, enhanced shortwave radiation and a shallower mixed layer were culprits. In the Southwest Pacific, the heat was attributed to reduced cloud cover and increased advection. The Tropical Eastern Pacific was influenced by oceanic advection.

Notice anything? These aren’t unified, global changes due to increased CO2. They are local, meteorological, and oceanographic phenomena—exactly the kinds of natural variability we should expect in a dynamic system. The fact that these local causes are acknowledged undercuts the paper’s own argument for a singular, global cause rooted in greenhouse gas emissions.

Bad science and an unjustified extrapolation is the gist of this study and press release. Perhaps the most egregious leap comes in the suggestion that the 2023 marine heatwaves might represent a “tipping point” in the Earth’s climate system. The term “tipping point” implies a sudden, irreversible shift—a planetary point of no return. But what evidence is there for this? The authors provide none beyond the temperature anomalies themselves and vague references to mixed-layer dynamics.

No historical precedent is given. No paleoclimatic comparisons are offered. No quantitative thresholds are defined. It’s all speculation dressed up in technical language.

Predictably, the press release connects the marine heatwaves to coral bleaching, fishery losses, and ecological disaster. While it is true that marine heatwaves can affect ecosystems, the narrative ignores the fact that marine species have adapted to variability over millions of years.

Corals, for instance, have survived past periods of much higher global temperatures. Many fish species migrate or dive to avoid surface heat. And let’s not forget: ecosystems are resilient. The doom-and-gloom language betrays a bias that prioritizes alarm over understanding.

My conclusion: another tale of confirmation bias

The 2023 marine heatwaves were notable, yes. But were they a sign of a planetary tipping point? Unlikely. The evidence is thin, the dataset is short, and the logic is stretched.

Here’s what we actually know:

• Our observational record of global ocean temperatures is limited to a few decades.
• Natural variability, including El Niño and decadal oscillations, can easily account for short-term spikes.
• The study’s own data points to region-specific, localized drivers.
• The models used, while complex, are not infallible representations of reality.
• No historical context or thresholds are provided to justify claims of a tipping point.

Science should seek to inform, not frighten. The AAAS release on this study opts for drama over depth, projection over precision. In doing so, it exemplifies what’s wrong with climate discourse today: a preference for narrative over nuance.

Let’s not mistake a one year snapshot for a trend—or worse, for a crisis.

The paper: Record-breaking 2023 marine heatwaves

Dong et al., Science 24 Jul 2025 Vol 389, Issue 6758 pp. 369-374

https://www.science.org/doi/10.1126/science.adr0910

Abstract

The year 2023 witnessed an extraordinary surge in marine heatwaves (MHWs) across Earth’s oceans, setting new records in duration, extent, and intensity, with MHW activity totaling 53.6 billion °C days square kilometer—more than three standard deviations above the historical norm since 1982. Notable events include the North Atlantic MHW (276-year return period) and the Southwest Pacific (141 years). Using ECCO2 (Estimating the Circulation and Climate of the Ocean-Phase II) high-resolution daily data, we conducted a mixed-layer heat budget analysis and identified region-specific drivers: enhanced shortwave flux and a shallower mixed layer in the North Atlantic and North Pacific, reduced cloud cover and increased advection in the Southwest Pacific, and oceanic advections in the Tropical Eastern Pacific. The 2023 MHWs highlight the intensifying impacts of a warm climate and the challenges in understanding extreme events.