Science Snippets: Global Ocean is Warmer Than Previously Believed

Draft script:

As I have pointed out previously in this space, the global ocean accounts for about 70% of the area of Earth. The vast expanse of saltwater holds more than 96% of water on this planet. All life on Earth arose from marine life. As the global ocean goes, so goes life on Earth.

From SciTechDaily on 10 August 2025 comes an article titled Earth’s Oceans Are Boiling. And It’s Worse Than We Thought. The subhead: “In 2023, the world’s oceans endured the most extreme and prolonged marine heatwaves in recorded history, with some lasting over 500 days and covering nearly the entire globe.” This article was published two years after this event because scientific documentation takes time.

Here’s the lede: “These unprecedented temperature spikes devastated coral reefs, disrupted marine food chains, and threatened global fisheries.”

Beneath a subhead titled “Unprecedented Ocean Heat in 2023,” two paragraphs explain how dire the ocean heating was: “The marine heatwaves … that swept across the globe in 2023 were unlike anything seen before in terms of strength, persistence, and size, according to a new scientific analysis. Researchers have identified the regional factors behind these extraordinary events and linked them to broader shifts in Earth’s climate system. Their work also raises concerns that the planet may be edging toward a climate tipping point. [marine heatwaves] … are extended periods when ocean temperatures soar far above normal levels.

Such episodes can cause serious harm to ocean life, triggering widespread coral bleaching and large-scale die-offs. They also threaten economies by disrupting fishing and aquaculture. Experts widely agree that human-driven climate change is causing both the frequency and severity of [marine heatwaves] … to rise sharply.”

The next subsection is cleverly titled “A Global Wave of Extremes.” It introduces a peer-reviewed paper: “In 2023, vast stretches of the North Atlantic, Tropical Pacific, South Pacific, and North Pacific were gripped by extreme [marine heatwaves] …. While the impacts were clear, the precise causes behind the timing, duration, and strengthening of these widespread events have not been fully understood.

To investigate, Tianyun Dong and colleagues conducted a detailed global study using a combination of satellite data and ocean reanalysis, including high-resolution information from the ECCO2 project. ECCO2 refers to Estimating the Circulation and Climate of the Ocean-Phase II.”

The following subsection is titled “Recording-Breaking Intensity and Spread.” It includes these two paragraphs: “The team found that the 2023 [marine heatwaves] … surpassed all previous records for intensity, length, and coverage. These events persisted four times longer than the historical average and spread across 96% of the world’s oceans. The most extreme heating took place in the North Atlantic, Tropical Eastern Pacific, North Pacific, and Southwest Pacific, which together made up 90% of the total ocean heat anomalies recorded.

One striking example was the North Atlantic heatwave, which began in mid-2022 and lasted an extraordinary 525 days. In the Southwest Pacific, the affected area was larger and endured longer than any previously observed event. In the Tropical Eastern Pacific, water temperatures rose by as much as 1.63 degrees Celsius during the early stages of El Niño.”

The final subsection, titled Triggers Behind the Heatwaves, briefly explains the peer-reviewed paper: “By applying a mixed-layer heat budget analysis, the scientists identified several contributing factors that varied by region. These included more sunlight reaching the ocean due to fewer clouds, weaker winds, and unusual shifts in ocean currents. According to the researchers, the scale and nature of the 2023 [marine heatwaves] … may reflect a significant change in how the ocean and atmosphere interact, potentially serving as an early signal of a climate tipping point.”

The article at SciTechDaily cannot admit that a climate tipping point has already occurred. It certainly cannot admit that dozens of these self-reinforcing feedback loops have already been breached.

I turn now to the peer-reviewed paper, which was published in the renowned journal, Science and titled Record-breaking 2023 marine heatwaves. Authored by 17 scholars, the paper begins with an Editor’s summary: “Ocean surface temperatures vary from year to year, experiencing heat waves like those felt on land, but 2023 saw an extraordinarily large increase in marine heat waves with no recent analog. Dong et al. report that 2023 set new records in the duration, extent, and intensity of these events by as much as three standard deviations above the historical average of the past four decades. The increasing trends in marine heat waves present intensifying dangers to ecological, social, and economic systems.”

I suspect it goes without saying that “marine heat waves present intensifying dangers to ecological, social, and economic systems.” These dangers also extend to the existential threat of human extinction and therefore to all life on Earth.

The peer-reviewed paper is not open-access. However, the Abstract tells the story: “The year 2023 witnessed an extraordinary surge in marine heatwaves … across Earth’s oceans, setting new records in duration, extent, and intensity, with [marine heatwave] … activity totaling 53.6 billion °C days [per] square kilometer—more than three standard deviations above the historical norm since 1982. Notable events include the North Atlantic marine heatwave … (276-year return period) and the Southwest Pacific (141 years). Using ECCO2 ([which, as I mentioned earlier, represents] 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 later in the North Atlantic and North Pacific, reduced cloud clover and increased advection in the Southwest Pacific, and oceanic advections in the Tropical Eastern Pacific. The 2023 [marine heatwaves] … highlight the intensifying impacts of a warm climate and the challenges in understanding extreme events.”

Again, as the global ocean goes, so goes life on Earth. The global ocean is already too hot, and it is warming rapidly. This pattern does not bode well for life on this planet. Neither the article in SciTechDaily nor the peer-reviewed paper in Science provide the customary line about how we can save ourselves by reducing greenhouse gas emissions. Perhaps there is a growing consensus that Earth is amid abrupt, irreversible climate change, with an emphasis on irreversible.