This figure shows changes in heat content of the top 700 meters of the world’s oceans between 1955 and 2023 (US EPA)
A new study published in ScienceDaily claims severe ocean overheating may be causing a fundamental climate shift. Ocean heatwaves over the past couple of years have been massive and extensive and intensive on a scale never seen before at times covering 96% of the world’s oceans, which should be impossible. (The Oceans are Overheating – and Scientists Say a Climate Tipping Point May be Here, ScienceDaily d/d July 26, 2025)
Starting in 2022-23, massive ocean heatwaves persisted for more than 500 days covering nearly the entire globe. This shocking event, never witnessed before, puts the entire global warming scenario on a new level that’s predictably negative. The message is as clear as a bell: World leadership should focus on removal of fossil fuel emissions as soon as possible. Global warming, especially in the ocean, is on a rapid upswing and not waiting around, as such, fully 2/3rds of the planet is suffering a very dangerous heat stroke that’s separate and apart from extreme heatwaves on land.
After all, Earth is basically a liquid planet, according to NASA: “Covering more than 70% of Earth’s surface, our global ocean has a very high heat capacity. It has absorbed 90% of the warming that has occurred in recent decades due to increasing greenhouse gases, and the top few meters of the ocean store as much heat as Earth’s entire atmosphere.” (Ocean Warming/ Vital Signs, NASA)
Scientists fear system-wide climate change may be in the works, threatening ocean marine ecosystems such corals, fisheries, and aquaculture, as well as goosing up terrestrial temperatures way too fast too soon across the planet. Marine heatwaves this decade have lasted four times (4x) longer than the historical record. Hot oceans accelerate climate change. As water temperatures rise, oceans lose ability to absorb excessive heat and land temperatures rise accordingly.
“According to the study’s researchers, the 2023 MHWs may mark a fundamental shift in ocean-atmosphere dynamics, potentially serving as an early warning of an approaching tipping point in Earth’s climate system,” Ibid.
Given the duration of the heatwave, which began in earnest in 2023 and continues today in some regions, Zhenzhong Zeng, PhD, co-author of the study, Earth systems scientist China Southern University of Science and Technology believes it is the start of a “new normal for the world’s oceans.” Emerging data indicates the heat in the oceans is accumulating exponentially, a trend that defies climate model predictions. It’ll accelerate heat on land, leading to more severe and widespread droughts, heatwaves, wildfires and storms, which are already seriously severe in today’s world.
Zhenzhong Zeng claims to be “very scared” by the potential regime shift in the oceans: “I think almost all of the Earth system model projections are wrong… Record marine heatwaves may signal a permanent shift in the oceans.”
Some impacts of the shift are starting to appear: “When Ocean temperatures rise dramatically, they trigger a cascade of effects that lead to mass fish deaths. The primary mechanism involves oxygen depletion, as warmer water holds less dissolved oxygen while simultaneously increasing fish’s metabolic rates and oxygen requirements. This double impact can lead to widespread suffocation. Additionally, fish are ectothermic (cold-blooded), making them particularly vulnerable to temperature changes.” (Marine Heatwaves Trigger Mass Fish Deaths in Australian Waters, Aussie Animals, 2025)
Devastating results hit western Australia early in 2025. Temperatures 5°C above normal killed tens of thousands of fish. Scientists agree this represents a broader global challenge as research shows climate change has multiplied the event of marine heat zones by 20 times. Now, it’s coming home to roost as the world’s oceans turn away from decades of absorbing excessive global heat.
Ocean Payback
According to Woods Hole Oceanographic Institution, the ocean won’t hold its heat forever. Eventually, it’ll feed back into the climate system, causing acceleration of global warming beyond all expectations, as “it’s too late” becomes reality.
It’s not just oceans that are overheating: “Water temperatures have surged above 85 degrees in the Mediterranean Sea, where records have been broken every day for weeks.” (The Mediterranean Sea is Experiencing a Record-Smashing Heat Wave, The Washington Post, July 4, 2025) Scientists have expressed concern over the potential for sizeable losses of marine life.
Ocean Heat Impact – Antarctica & Greenland
The Greenland and Antarctic Ice Sheets represent the largest land store of freshwater, which, should they completely melt and flow into the ocean, would add a total of 7.5 and 58 m to global-mean sea level, respectively. Recent observations have shown the ice sheets melting at an accelerating rate. Now, ocean heat has become a bigger-than-expected threat to the stability of the major ice sheets much, much earlier than science expected.
The Greenland ice sheet is particularly vulnerable, as warm ocean currents undercut fjords and erode outlet glaciers, undercutting and destabilizing calving.
The leading cause of ice mass loss for the West Antarctica Ice Sheet is ocean heat. Only recently, under the auspices of the Australian Antarctic Program Partnership, 450 polar scientists held an emergency meeting to alert the world to clear evidence of instability of the ice sheet. They strongly suggest immediate halt to fossil fuels.
Statement of Polar scientists’ group: “The services of the Southern Ocean and Antarctica – oceanic carbon sink and planetary air-conditioner – have been taken for granted. Global warming-induced shifts observed in the region are immense. Recent research has shown record-low sea ice, extreme heatwaves exceeding 40°C [104°F] above average temperatures, and increased instability around key ice shelves. Shifting ecosystems on land and at sea underscore this sensitive region’s rapid and unprecedented transformations. Runaway ice loss causing rapid and catastrophic sea-level rise is possible within our lifetimes. Whether such irreversible tipping points have already passed is unknown.” (“Emergency” Warning for Antarctica Issued by Nearly 500 Polar Scientists, IFLScience, Nov. 22, 2024)
Unfortunately, climate change is not about to go away, rather, it is gaining momentum by the year as CO2 emissions from fossil fuels skyrocket into the atmosphere, as of June 2025 at 430 ppm, a new record high for atmospheric concentration. Moreover, the annual rate of CO2 increase in 2024 (also setting a new record) was 3.50 ppm, more than double the annual rate in 2000 at 1.24 ppm, when atmospheric CO2 concentration was at 37o ppm.
According to the Intergovernmental Panel on Climate Change, in 2015 an international group of scientists determined anything above 350 ppm atmospheric CO2 would be beyond the “safe zone.” Nobody has suggested the scientists have changed their minds. But that issue is now upstaged by the world’s property/casualty insurance industry as it screams, hollers, complains, rejects, doubles rates, drops coverage all because of climate change. Property insurers have brought to the fore in full public view a climate change monster that’s destroying the American dream of home ownership.
Based upon referenced sources herein, fossil fuel emissions must be stopped as soon as possible to hopefully mitigate a whacky climate system that is already threatening the very foundations of the current socio/economic system, unwittingly suggesting maybe ‘it should also go’ the way of fossil fuels.
As if out of the blue, within only a couple of years, climate change has become capitalism’s biggest nightmare. Maybe they should scramble to do whatever is scientifically necessary to try to mitigate whatever can be mitigated. Too bad CO2 capture and sequester is a decidedly weak, and inconsequential, solution. “It’s a fraud!” (Al Gore)
Robert Hunziker
Los Angeles
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