By Javier Vinos
The climate event of 2023 was truly exceptional, but the prevailing catastrophism about climate change hinders its proper scientific analysis. I present arguments that support the view that we are facing an extraordinary and extremely rare natural event in climate history.
1. Off-scale warming
Since the planet has been warming for 200 years, and our global records are even more recent, every few years a new warmest year in history is recorded. Despite all the publicity given each time it happens, it would really be news if it didn’t happen, as it did between 1998 and 2014, a period popularly known as the pause.
Figure 1. Berkeley Earth temperature anomaly
Since 1980, 13 years have broken the temperature record. So, what is so special about the 2023 record and the expected 2024 record? For starters, 2023 broke the record by the largest margin in records, 0.17C. This may not sound like much, but if all records were by this margin, we would go from +1.5C to +2C in just 10 years, and reach +3C 20 years later.
Figure 2. Berkeley Earth 2023 temperature anomaly
Moreover, to produce so much warming, almost the entire globe experienced above-average warming. 2023 was a year of real global warming, although most of the warming occurred in the Northern Hemisphere.
As a result, one of the major databases, Berkeley Earth, has exceeded the +1.5C limit for a full year for the first time, and 2024 promises another temperature record. Crossing the dangerous warming threshold so early has caused some confusion, exacerbated by the fact that not much difference seems to be noticeable. Even Arctic ice remains above the average of the last decade. And if we’ve already crossed the line and the climate is beyond repair, what’s the point of trying?
Figure 3. Global temperature calculation by Copernicus system.
But the authorities have been quick to point out that even if we are above +1.5C in 2023 or 2024, we will not have crossed the threshold. There is a catch. The global temperature is not the temperature of one month or one year, but the temperature of the linear trend of the last 30 years, which according to the European Copernicus system is +1.28C and is expected to exceed +1.5C in 10 years. Link
2. Uncharted territory
In June 2023, the North Atlantic experienced a heat wave unprecedented in 40 years, with temperatures 5C warmer than usual. Carlo Buontempo, the director of Copernicus, said the world was “entering uncharted territory. We have never seen anything like this in our life”. To understand what has puzzled scientists so much, it is necessary to look at the evolution of the temperature of the Earth’s oceans throughout the year since 1979.
Figure 4. 60°N-60°S global ocean surface temperature by year since 1979.
On average, the Earth’s oceans are warmest in February-March and coldest in October-November, with an intermediate maximum in August. This is an annual cycle caused by the tilt of the Earth’s axis, the arrangement of the continents, and seasonal changes in atmospheric circulation and albedo. A cycle that has never been broken as long as measurements have been kept until 2023. This year shows an accentuated warming since January, leading to daily temperature records since the beginning of April. But what is absolutely astonishing is that the ocean continued to warm in June and July and reached an annual maximum in August, something that has never happened before. And the warming through August is staggering, about 0.33C above the 2016 record, which is huge for the ocean. After that, the annual cycle begins to behave normally, but at a much higher temperature, which is slowly falling. In June 2024, after 415 days of record temperatures, the ocean is still about 0.2C warmer than it should be.
Buontempo means good weather in English, and his phrase “we have entered uncharted territory” has become very popular. However, it assumes that we have reached and will remain in this situation, whereas the data suggest that this is a one-off anomaly with diminishing effects. For now, it tells us that nothing dramatic is happening as we approach the politically established warming threshold.
Gavin Schmidt, director of NASA’s climate monitoring institute, also uses the expression “uncharted territory” when he explains that the 2023 anomaly worries scientists, saying that climate models cannot explain why the planet’s temperature suddenly spiked in 2023. Not only was the temperature anomaly much larger than expected, but it occurred months before the onset of El Nino. In his own words: “The 2023 temperature anomaly has come out of the blue, revealing an unprecedented knowledge gap perhaps for the first time since about 40 years ago. It could imply that a warming planet is already fundamentally altering how the climate system operates, much sooner than scientists had anticipated.”[iii] According to Gavin, we could have broken the climate and the models would no longer work.
Instead of abandoning science for wild speculation let’s examine the possible factors responsible for the abrupt warming that Gavin Schmidt dismisses by saying they could explain at most a few hundredths of a degree, for which he has little evidence.
3. The little boy is innocent
El Nino is unlikely to be responsible for the simple reason that such abrupt global warming is unprecedented in our records, and El Nino has many precedents. In addition, El Niño warms a specific region of the equatorial Pacific and primarily affects the Pacific, while the “2023 event” warmed parts of the North Atlantic to an extraordinary degree. This does not prevent scientists like Jan Esper and Ulf Büntgen from saying that 2023 is consistent with a greenhouse gas-induced warming trend amplified by an El Niño.[iv] They clearly did not examine the data before writing this, nor did the reviewers of their Nature paper.
The relationship between the temperature of the equatorial Pacific and that of the global ocean during an El Nino is shown in the figure below.
Figure 5. Niño 3.4 temperature anomaly (red) and detrended satellite global ocean temperature anomaly (black).
The temperature anomaly in the Pacific Nino 3.4 region shows the very strong Ninos of 1983, 1998, and 2016, and the strong Ninos of 1988, 1992, 2009, and 2024. The years correspond to the month of January during the event. When the satellite global ocean temperature anomaly is plotted without its long-term trend, we observe a very close correspondence. The long-term trend responds to other causes, but the temperature variations correspond to the export of heat from the equatorial Pacific to the rest of the globe.
We also observe two things. The first is that the correspondence fails in two periods, in 1992 as a result of the Pinatubo eruption a year earlier, and in 2024. The second observation is that in all strong or very strong Niños, the source of the heat, the equatorial Pacific, warms earlier and warms more or as much in relative terms as the global ocean warms later. This does not happen in the 2024 El Niño. The warming is simultaneous and greater than it should be outside the equatorial Pacific.
Figure 7. Niño 3.4 temperature anomaly (red) and detrended ERSST PDO (blue).
The Pacific Decadal Oscillation (PDO) is often described as a long-lived pattern of climate variability similar to El Niño in the North Pacific. And this is evident when we compare the two after removing a long-term trend that the PDO should not have. The agreement is very strong, and again we see a significant anomaly in 1991 due to the Pinatubo eruption. But even more important is the anomaly in 2023-24, when the PDO shows extraordinarily small changes and remains negative when it should be positive.
Figure 8. During the 2023 event the North Pacific stayed in negative PDO conditions, while the equatorial Pacific displayed El Niño conditions.
To understand this response, one must consider that the warm phase of the PDO requires the Northwest Pacific to be cold, but as we have shown above, the Northwest Pacific was very warm in 2023, causing the PDO to remain in a cold phase. A negative phase of the PDO during El Niño is unprecedented and categorically rules out El Niño as the cause of the abrupt warming that has puzzled scientists. In fact, it is possible that the ocean warming that began in March 2023 was the cause of the 2024 El Niño by weakening the trade winds in the equatorial Pacific.
I’d like to thank Charles May for bringing this data to my attention and for doing such an excellent job analyzing it each month.
4. Sulfate aerosols are not responsible
Another possibility that is under consideration is the reduction of sulfate aerosols as a result of the change in marine fuel regulations in 2020.
Figure 9. Global sulfur emissions for the past 64 years
The reduction in sulfur emissions since the late 1970s is considered a significant warming factor by reducing emissions of shortwave radiation reflected from the atmosphere. However, the reduction in sulfur dioxide emissions from marine fuels since 2020 is estimated at 14% of total emissions.
Figure 10. Model-calculated global temperature effect of an 80% reduction (red curve) in marine fuel sulfur content from pre-2020 situation (blue curve), and decadal mean difference (green bars).
A recent study, still under peer review, used a climate model to calculate that sulfur emission reductions from 2020 could cause global warming of 0.02°C in the first decade.[v] Since the warming in 2023 was 10 times greater, it is difficult to believe that emissions reductions since 2020 could have been a major factor in the abrupt warming in 2023.
In the figure, the blue curve is the global warming predicted with the previously used marine fuel, and the red curve is the one predicted with the fuel with 80% less sulfur. The difference between the two curves for the decade 2020-30 is the green bar of 0.02°C.
5. CO₂ increase didn’t do it
The amount of CO₂ in the atmosphere has increased slightly by about 2.5 parts per million in 2023.
Figure 11. Monthly (red) and 12-month (black) CO₂ levels at Mauna Loa.
The increase from 418.5 to 421 ppm represents an increase of 0.6% and is similar to the increase that has occurred each year for the past several decades. Nothing in our knowledge of the effect of CO₂ increases on climate suggests that such a small increase could have led to such a large and abrupt warming. There is no study to suggest that the gradual increase in CO₂ could lead to a sudden increase in climate variability. Therefore, all model predictions are long-term and affect the statistics of weather phenomena. The proof is that scientists and models cannot explain what happened in 2023.
6. Tonga volcano prime suspect
Just over a year before the abrupt warming, in January 2022, an extremely unusual volcanic eruption took place in Tonga. How unusual? It was an eruption of VEI 5 explosivity, capable of reaching the stratosphere, which occurs on average every 10 years.
Figure 12. Time and cone elevation of VEI ≥5 volcanic eruptions of the past 200 years, their distribution by altitude (yellow bars), and the suggested depth for a submarine eruption capable of projecting a large amount of water to the stratosphere (red line).
There have been a number of eruptions with VEI 5 or higher in the last 200 years, although not all of them have affected the global climate. This figure shows with dots the date they occurred and the elevation at which the volcanic cone was located. The yellow bars show the distribution of eruptions in 500 m elevation bins. The Tonga eruption was a submarine explosion at very shallow depths, about 150 m below the sea surface. It ejected 150 million tons of water into the stratosphere.
In our 200 years of records there is only one other submarine eruption with VEI 5, which occurred in 1924 off the Japanese island of Iriomote at a depth of 200 m and did not affect the atmosphere. Only surface effects were observed. NASA scientists believe that the Tonga explosion occurred at the right depth to project a lot of water into the stratosphere.[vi] This depth is indicated by the red line. So, the Tonga eruption is a once in 200-year event, probably less than once in a millennium. Science was very lucky. We are not so lucky.
We know that strong volcanic eruptions, capable of reaching the stratosphere, can have a very strong effect on the climate for a few years, and that this effect can be delayed by more than a year. The eruption of Mount Tambora in April 1815 had a global effect on the climate, but it took 15 months for the effect to develop, during the year without a summer of 1816. These delayed effects coincided with the appearance of a veil of sulfate aerosols in the Northern Hemisphere atmosphere due to seasonal changes in the global stratospheric circulation.
Figure 13. Stratospheric water vapor anomaly at 45°N.
In this image on the vertical axis, we observe the water vapor anomaly in the stratosphere between 15 and 40 km altitude with ocher tones for negative values and greenish for positive ones. The measurement takes place at 45° latitude in the northern hemisphere. On the horizontal axis is the date, and we can see that the large anomaly created by the Tonga eruption does not appear in the Northern Hemisphere until one year later, in 2023, when the warming occurred. Thus, there are dynamical events in the stratosphere that have the appropriate time lag to coincide with the abrupt warming in 2023.
Because the Tonga eruption is unprecedented, there is much about its effects that we do not understand. But we do know that the planetary greenhouse effect is very sensitive to changes in stratospheric water vapor because, unlike the troposphere, the stratosphere is very dry and far from greenhouse saturation.
As a group of scientists showed in 2010, the effect of changes in stratospheric water vapor is so important that the warming between 2000 and 2009 was reduced by 25% because it decreased by 10%.[vii] And after the Tonga eruption, it increased by 10% because of the 150 million tons of water released into the stratosphere, so we could have experienced much of the warming of an entire decade in a single year.
Figure 14. Global water vapor anomaly above 68hPa.
The stratosphere has already begun to dry out again, but it is a slow process that will take many years. In 2023 only 20 million tons of water returned to the troposphere, 13%.[viii]
7. Dismissing natural warming
On the one hand, we have an absolutely unprecedented abrupt warming that the models cannot explain and that has scientists scratching their heads. Such anomalous warming cannot logically respond to the usual suspects, El Niño, reduced sulfur emissions, or increased CO₂, which have been going on for many decades.
On the other hand, we have an absolutely unprecedented volcanic eruption, the effects of which we cannot know, but which, according to what we know about the greenhouse effect, should cause significant and abrupt warming.
Of course, we cannot conclude that the warming was caused by the volcano, but it is clear that it is by far the most likely suspect, and any other candidate should have to demonstrate its ability to act abruptly with such magnitude before being seriously considered.
So why do scientists like Gavin Schmidt argue, without evidence or knowledge, that the Tonga volcano could not have been responsible? If the effect were cooling, the volcano would be blamed without a second’s hesitation, but significant natural warming undermines the message that warming is the fault of our emissions.
This article can also be watched in a 19-minute video with English and French subtitles.
Copernicus Global temperature trend monitor.
[ii] CNN July 8, 2023. Global heat in ‘uncharted territory’ as scientists warn 2023 could be the hottest year on record.
[iii] Schmidt, G., 2024. Why 2023’s Heat Anomaly Is Worrying Scientists. Nature, 627.
[iv] Esper, J. et al., 2024. 2023 summer warmth unparalleled over the past 2,000 years. Nature, pp.1-2.
[v] Yoshioka, M., et al., 2024. Warming effects of reduced sulfur emissions from shipping. EGUsphere, 2024, pp.1-19.
[vi] Lee, J., & Wang, A., 2022. Tonga eruption blasted unprecedented amount of water into stratosphere. NASA Jet Propulsion Lab.
[vii] Solomon, S., et al., 2010. Contributions of stratospheric water vapor to decadal changes in the rate of global warming. Science, 327 (5970), pp.1219-1223.
[viii] Zhou, X., et al. 2024. Antarctic vortex dehydration in 2023 as a substantial removal pathway for Hunga Tonga‐Hunga Ha’apai water vapor. Geophysical Research Letters, 51 (8), p. e2023GL107630.
[ix] Guterres, A., 2024. Secretary-General’s special address on climate action “A Moment of Truth”.
