How Much Will Reduction in Shipping Emissions Stoke Global Warming?

A controversial new research paper claims that a major reduction in emissions of SO₂ (sulfur dioxide) since 2020, due to a ban on the use of high-sulfur fuels by ships, could result in additional global warming of 0.16 degrees Celsius (0.29 degrees Fahrenheit) for seven years – over and above that from other sources. The paper was published by a team of NASA scientists.

This example of the law of unintended consequences, if correct, would boost warming from human CO₂, as well as that caused by water vapor in the stratosphere resulting from the massive underwater eruption of the Hunga Tonga–Hunga Haʻapai volcano in 2022. The eruption, as I described in a previous post, is likely to raise global temperatures by 0.035 degrees Celsius (0.063 degrees Fahrenheit) during the next few years.

It’s been known for some time that SO₂, including that emanating from ship engines, reacts with water vapor in the air to produce aerosols. Sulfate aerosol particles linger in the atmosphere, reflecting incoming sunlight and also acting as condensation nuclei for the formation of reflective clouds. Both effects cause global cooling.

In fact, it was the incorporation of sulfate aerosols into climate models that enabled the models to successfully reproduce the cooling observed between 1945 and about 1975, a feature that had previously eluded modelers.   

On January 1, 2020, new IMO (International Maritime Organization) regulations lowered the maximum allowable sulfur content in international shipping fuels to 0.5%, a significant reduction from the previous 3.5%. This air pollution control measure has reduced cloud formation and the associated reflection of shortwave solar radiation, both reductions having inadvertently increased global warming.

As would be expected, the strongest effects show up in the world’s most traveled shipping lanes: the North Atlantic, the Caribbean and the South China Sea. The figure on the left below depicts the researchers’ calculated contribution from reduced cloud fraction to additional radiative forcing resulting from the SO₂ reduction. The figure on the right shows by how much the concentration of condensation nuclei in low maritime clouds has fallen since the regulations took effect.

The cloud fraction contribution is 0.11 watts per square meter. The other contributions, from a reduction in cloud water content and the drop in reflection of solar radiation, add up to a total of 0.2 watts per square meter extra radiative forcing averaged over the global ocean, arising from the new shipping regulations, the NASA scientists say.

The effect is concentrated in the Northern Hemisphere since there is relatively little shipping traffic in the Southern Hemisphere. The researchers calculate the boost to radiative forcing to be 0.32 watts per square meter in the Northern Hemisphere, but only 0.1 watts per square meter in the Southern Hemisphere. The hemispheric difference in their calculations of absorbed shortwave solar radiation (near the earth’s surface) can be seen in the following figure, to the right of the dotted line.

According to the paper, the additional radiative forcing of 0.2 watts per square meter since 2020 corresponds to added global warming of 0.16 degrees Celsius (0.29 degrees Fahrenheit) over seven years. Such an increase implies a warming rate of 0.24 degrees Celsius (0.43 degrees Fahrenheit) per decade from reduced SO₂ emissions alone, which is more than double the average warming rate since 1880 and 20% higher than the mean warming rate since 1980 of approximately 0.19 degrees Celsius (0.34 degrees Fahrenheit) per decade.

The researchers remark that the forcing increase of 0.2 watts per square meter is a staggering 80% of the measured gain in forcing from other sources since 2020, the net planetary heat uptake since then being 0.25 watts per square meter.

However, these controversial claims have been heavily criticized, and not just by climate change skeptics. Climate scientist and modeler Zeke Hausfather points out that total warming will be less than the estimated 0.16 degrees Celsius (0.29 degrees Fahrenheit), because the new shipping regulations have only a minimal effect on land, which covers 29% of the earth’s surface.

And, states Hausfather, the researchers’ energy balance model “does not reflect real-world heat uptake by the ocean, and no actual climate model has equilibration times anywhere near that fast.” Hausfather’s own 2023 estimate of additional warming due to the use of low-sulfur shipping fuels was a modest 0.045 degrees Celsius (0.081 degrees Fahrenheit) after 30 years, as shown in the figure below.

Further criticism of the paper’s methodology comes from Laura Wilcox, associate professor at the National Centre for Atmospheric Science at the University of Reading. Wilcox told media that the paper makes some “very bold statements about temperature changes … which seem difficult to justify on the basis of the evidence.” She also has concerns about the mathematics of the researchers' calculations, including the possibility that the effect of sulfur emissions is double-counted.

Next: Philippines Court Ruling Deals Deathblow to Success of GMO Golden Rice

The Sun Can Explain 70% or More of Global Warming, Says New Study

Few people realize that the popular narrative of overwhelmingly human-caused global warming, with essentially no contribution from the sun, hinges on a satellite dataset showing that the sun’s output of heat and light has decreased since the 1950s.

But if a different but plausible dataset is substituted, say the authors of a new study, the tables are turned and a staggering 70% to 87% of global warming since 1850 can be explained by solar variability. The 37 authors constitute a large international team of scientists, headed by U.S. astrophysicist Willie Soon, from many countries around the world.

The two rival datasets, each of which implies a different trend in solar output or TSI (total solar irradiance) since the late 1970s when satellite measurements began, are illustrated in the figure below, which includes pre-satellite proxy data back to 1850. The TSI and associated radiative forcing – the difference in the earth’s incoming and outgoing radiation, a difference which produces heating or cooling – are measured in units of watts per square meter, relative to the mean from 1901 to 2000.   

The upper graph (Solar #1) is the TSI dataset underlying the narrative that climate change comes largely from human emissions of greenhouse gases, and was used by the IPCC (Intergovernmental Panel on Climate Change) in its 2021 AR6 (Sixth Assessment Report). The lower graph (Solar #2) is a TSI dataset from a different satellite series, as explained in a previous post, and exhibits a more complicated trend since 1950 than Solar #1.

To identify the drivers of global warming since 1850, the study authors carried out a statistical analysis of observed Northern Hemisphere land surface temperatures from 1850 to 2018; the temperature record is shown as the black line in the next figure. Following the approach of the IPCC’s AR6, three possible drivers were considered: two natural forcings (solar and volcanic) and a composite of multiple human-caused or anthropogenic forcings (which include greenhouse gases and aerosols), as employed in AR6.   

Time series for the different forcings, or a combination of them, were fitted to the temperature record utilizing multiple linear regression. This differs slightly from the IPCC’s method, which used climate model hindcasts based on the forcing time series as an intermediate step, as well as fitting global land and ocean, rather than Northern Hemisphere land-only, temperatures.

The figure below shows the new study’s best fits to the Northern Hemisphere land temperature record for four scenarios using a combination of solar, volcanic and anthropogenic forcings. Scenarios 1 and 2 correspond to the Solar #1 and Solar #2 TSI time series depicted in the first figure above, respectively, combined with volcanic and anthropogenic time series. Scenarios 3 and 4 are the same without the anthropogenic component – that is, with natural forcings only. Any volcanic contribution to natural forcing usually has a cooling effect and is short in duration.

The researchers’ analysis reveals that if the Solar #1 TSI time series is valid, as assumed by the IPCC in AR6, then natural (solar and volcanic) forcings can explain at most only 21% of the observed warming from 1850 to 2018 (Scenario 3). In this picture, adding anthropogenic forcing brings that number up to an 87% fit (Scenario 1).

However, when the Solar #1 series is replaced with the Solar #2 series, then the natural contribution to overall warming increases from 21% to a massive 70% (Scenario 4), while the combined natural and anthropogenic forcing number rises from an 87% to 92% fit (Scenario 2). The better fits with the Solar #2 TSI time series compared to the Solar #1 series are visible if you look closely at the plots in the figure above.

These findings are enhanced further if urban temperatures are excluded from the temperature dataset, on the grounds that urbanization biases temperature measurements upward. The authors have also found that the long-term warming rate for rural temperature stations is only 0.55 degrees Celsius (0.99 degrees Fahrenheit) per century, compared with a rate of 0.89 degrees Celsius (1.6 degrees Fahrenheit) per century for rural and urban stations combined, as illustrated in the figure below.

Fitting the various forcing time series to a temperature record based on rural stations alone, the natural contribution to global warming rises from 70% to 87% when the Solar #2 series is used.

If the Solar #2 TSI time series represents reality better than the Solar #1 series used by the IPCC, this means that between 70% and 87% of global warming is mostly natural and the human-caused contribution is less than 30% – the complete opposite to the IPCC’s claim of largely anthropogenic warming.

Unsurprisingly, such an upstart conclusion has raised some hackles in the climate science community. But the three lead authors of the study have effectively countered their critics in lengthy, detailed rebuttals (here and here).

The study authors do point out that “it is still unclear which (if any) of the many TSI time series in the literature are accurate estimates of past TSI,” and say that we cannot be certain yet whether the warming since 1850 is mostly human-caused, mostly natural, or some combination of both. In another paper they remark that, while three of 27 or more different TSI time series can explain up to 99% of the warming, another seven time series cannot account for more than 3%.

Next: Challenges to the CO2 Global Warming Hypothesis: (9) Rotation of the Earth’s Core as the Source of Global Warming

Record Heat May Be from Natural Sources: El Niño and Water Vapor from 2022 Tonga Eruption

The record heat worldwide over the last few months – simultaneous heat waves in both the Northern and Southern Hemispheres, and abnormally warm oceans – has led to the hysterical declaration of “global boiling” by the UN Secretary General, the media and even some climate scientists. But a rational look at the data reveals that the cause may be natural sources, not human CO₂.

The primary source is undoubtedly the warming El Niño ocean cycle, a natural event that recurs at irregular intervals from two to seven years. The last strong El Niño, which temporarily raised global temperatures by about 0.14 degrees Celsius (0.25 degrees Fahrenheit), was in 2016. For comparison, it takes a full decade for current global warming to increase temperatures by that much. 

However, on top of the 2023 El Niño has been an unexpected natural source of warming – water vapor in the upper atmosphere, resulting from a massive underwater volcanic eruption in the South Pacific kingdom of Tonga in January 2022.

Normally, erupting volcanoes cause significant global cooling, from shielding of sunlight by sulfate aerosol particles in the eruption plume that linger in the atmosphere. Following the 1991 eruption of Mount Pinatubo in the Philippines, for example, the global average temperature fell by 0.6 degrees Celsius (1.1 degrees Fahrenheit) for more than a year.

But the eruption of the Hunga Tonga–Hunga Haʻapai volcano did more than just launch a destructive tsunami and shoot a plume of ash, gas, and pulverized rock 55 kilometers (34 miles) into the sky. It also injected 146 megatonnes (161 megatons) of water vapor into the stratosphere (the layer of the atmosphere above the troposphere) like a geyser. Because it occurred only about 150 meters (500 feet) underwater, the eruption immediately superheated the shallow seawater above and converted it explosively into steam.

Although the excess water vapor – enough to fill more than 58,000 Olympic-size swimming pools – was originally localized to the South Pacific, it quickly diffused over the whole globe. According to a recent study by a group of atmospheric physicists at the University of Oxford and elsewhere, the eruption boosted the water vapor content of the stratosphere worldwide by as much as 10% to 15%. 

Water vapor is a powerful greenhouse gas, the dominant greenhouse gas in the atmosphere in fact; it is responsible for about 70% of the earth’s natural greenhouse effect, which keeps the planet at a comfortable enough temperature for living organisms to survive, rather than 33 degrees Celsius (59 degrees Fahrenheit) cooler. So even 10–15% extra water vapor in the stratosphere makes the earth warmer.

The study authors estimated the additional warming from the Hunga Tonga eruption using a simple climate model combined with a widely available radiative transfer model. Their estimate was a maximum global warming of 0.035 degrees Celsius (0.063 degrees Fahrenheit) in the year following the eruption, diminishing over the next five years. The cooling effect of the small amount of sulfur dioxide (SO₂) from the eruption was found to be minimal.

As I explained in an earlier post, any increase in ocean surface temperatures from the Hunga Tonga eruption would have been imperceptible, at a minuscule 14 billionths of a degree Celsius or less. That’s because the oceans, which cover 71% of the earth’s surface, are vast and can hold 1,000 times more heat than the atmosphere. Undersea volcanic eruptions can, however, cause localized marine heat waves, as I discussed in another post.

Although 0.035 degrees Celsius (0.063 degrees Fahrenheit) of warming from the Hunga Tonga eruption pales in comparison with 2016’s El Niño boost of 0.14 degrees Celsius (0.25 degrees Fahrenheit), it’s nevertheless more than double the average yearly increase of 0.014 degrees Celsius (0.025 degrees Fahrenheit) of global warming from other sources such as greenhouse gases.

El Niño is the warm phase of ENSO (the El Niño – Southern Oscillation), a natural cycle that causes drastic temperature fluctuations and other climatic effects in tropical regions of the Pacific, as well as raising temperatures globally. Its effect on sea surface temperatures in the central Pacific is illustrated in the figure below. It can be seen that the strongest El Niños, such as those in 1998 and 2016, can make Pacific surface waters more than 2 degrees Celsius (3.6 degrees Fahrenheit) hotter for a whole year or so. 

Exactly how strong the present El Niño will be is unknown, but the heat waves of July suggest that this El Niño – augmented by the Hunga Tonga water vapor warming – may be super-strong. Satellite measurements showed that, in July 2023 alone, the temperature of the lower troposphere rose from 0.38 degrees Celsius (0.68 degrees Fahrenheit) to 0.64 degrees Celsius (1.2 degrees Fahrenheit) above the 1991-2020 mean.

If this El Niño turns out to be no stronger than in the past, then the source of the current “boiling” heat will remain a mystery. Perhaps the Hunga Tonga water vapor warming is larger than the Oxford group estimates. The source certainly isn’t any warming from human CO₂, which raises global temperatures gradually and not abruptly as we’ve seen in 2023.

Next: Has the Mainstream Media Suddenly Become Honest in Climate Reporting?

No Evidence That Hurricanes Are Becoming More Likely or Stronger

Despite the claims of activists and the mainstream media that climate change is making major hurricanes – such as U.S. Hurricane Harvey in 2017 or Hurricane Katrina in 2005 – more frequent and stronger, several recent studies have found no evidence for either of these assertions.

In fact, a 2022 study reveals that tropical cyclones in general, which include hurricanes, typhoons and tropical storms, are letting up as the globe warms. Over the period from 1900 to 2012, the study authors found that the annual number of tropical cyclones declined by about 13% compared with the period between 1850 and 1900, when such powerful storms were actually on the rise.

This is illustrated in the figure below, showing the tropical cyclone trend calculated by the researchers, using a combination of actual sea-level observations and climate model experiments. The solid blue line is the annual number of tropical cyclones globally, and the red line is a five-year running mean. 

The tropical cyclone trend is almost the opposite of the temperature trend: the average global temperature went down from 1880 to 1910, and increased by approximately 1.0 degrees Celsius (1.8 degrees Fahrenheit) between 1910 and 2012. After 1950, the rate of cyclone decline accelerated to about 23% compared to the 1850-1900 baseline, as global warming increased during the second half of the 20th century. Although the study authors noted a variation from one ocean basin to another, all basins demonstrated the same downward trend.

The authors remark how their findings are consistent with the predictions of climate models, in spite of the popular belief that a warming climate will spawn more, not fewer, hurricanes and typhoons, as more water evaporates into the atmosphere from the oceans and provides extra fuel. At the same time, however, tropical cyclone formation is inhibited by wind shear, which also increases as sea surface temperatures rise.    

Some climate scientists share the view of the IPCC (Intergovernmental Panel on Climate Change)’s Sixth Assessment Report that, while tropical cyclones overall may be diminishing as the climate changes, the strongest storms are becoming more common, especially in the North Atlantic. The next figure depicts the frequency of all major North Atlantic hurricanes back to 1851. Major hurricanes in Categories 3, 4 or 5 have a top wind speed of 178 km per hour (111 mph) or higher.

You can see that hurricane activity in this basin has escalated over the last 20 years, especially in 2005 and 2020. But, despite the upsurge, the data also show that the frequency of major North Atlantic hurricanes in recent decades is merely comparable to that in the 1950s and 1960s – a period when the earth was cooling rather than warming.

A team of hurricane experts concluded in a 2021 study that, at least in the Atlantic, the recent apparent increase in major hur­ricanes results from improvements in observational capabilities since 1970 and is unlikely to be a true climate trend. And, even though it appears that major Atlantic hurricanes were less frequent before about 1940, the lower numbers simply reflect the rela­tive lack of measurements in early years of the record. Aircraft re­connaissance flights to gather data on hurricanes only began in 1944, while satellite coverage dates only from the 1960s.

The team of experts found that once they corrected the data for under­counts in the pre-satellite era, there were no significant recent increases in the frequency of either major or all North Atlantic hurricanes. They suggested that the reduction in major hurricanes between the 1970s and the 1990s, clearly visible in the figure above, could have been the result of natural climate variability or possibly aerosol-induced weakening.

Natural climate cycles thought to contribute to Atlantic hurricanes include the AMO (Atlantic Multi-Decadal Oscillation) and La Niña, the cool phase of ENSO (the El Niño – Southern Oscillation). The AMO, which has a cycle time of approximately 65 years and alternates between warm and cool phases, governs many extremes, such as cyclonic storms in the Atlantic basin and major floods in eastern North America and western Europe. In the U.S., La Niñas influence major landfalling hurricanes.

Just as there’s no good evidence that global warming is increasing the strength of hurricanes, the same is true for their typhoon cous­ins in the northwestern Pacific. Although long-term data on major typhoons is not available, the frequency of all typhoon categories combined appears to be un­changed since 1951, according to the Japan Meteorological Agency. Yet a new study demonstrates a decline in both total and major typhoons for the 32-year period from 1990 to 2021, reinforcing the recent decrease in global tropical cyclones discussed above.

Next: Are Current Hot and Cold Extremes Climate Change or Natural Variability?

No Convincing Evidence That Cleaner Air Causes More Hurricanes

According to a new research study by NOAA (the U.S. National Oceanic and Atmospheric Administration), aerosol pollution plays a major role in hurricane activity. The study author claims that a recent decline in atmospheric pollutants over Europe and the U.S. has resulted in more hurricanes in the North Atlantic Ocean, while a boost in aerosols over Asia has suppressed tropical cyclones in the western Pacific.

But this claim, touted by the media, is faulty since the study only examines changes in aerosol emissions and hurricane frequency since 1980 – a selective choice of data becoming all too common among climate scientists trying to bolster the narrative of anthropogenic climate change. The aerosol pollution is mostly in the form of sulfate particles and droplets from industrial and vehicle emissions. When pre-1980 evidence is included, however, the apparent connection between aerosols and hurricanes falls apart.

Let’s look first at the North Atlantic. Data for the Atlantic basin, which has the best quality data in the world, do indeed show heightened hurricane ac­tivity over the last 20 years, particularly in 2005 and 2020. You can see this in the following figure, which illustrates the frequency of all major Atlantic hurricanes as far back as 1851. Major hurricanes (Category 3 or greater) have a top wind speed of 178 km per hour (111 mph) or higher. The recent enhanced activity is less pronounced, though still noticeable, for Category 1 and 2 hurricanes.

The next figure shows the observed increase in Atlantic hurricane frequency (top), from the 20 years between 1980 and 2000 to the 20 years between 2001 and 2020, compared to the NOAA study’s simulated change in sulfate aerosols during the same interval (bottom).

The hurricane frequency TCF is for all (Categories 1 through 5) hurricanes, with positive and negative color values denoting higher and lower frequency, respectively. A similar color scheme is used for the sulfate calculations. Both the Atlantic increase and western Pacific decrease in hurricane frequency are clearly visible, as well as the corresponding decrease and increase in aerosol pollution from 1980 to 2020.

But what the study overlooks is that the frequency of major Atlantic hurricanes in the 1950s and 1960s was at least compara­ble to that in the last two decades when, as the figure shows, it took a sudden upward hike from the 1970s, 1980s and early 1990s. If the study’s conclusions are correct, then pollution levels in Europe and the U.S. during the 1950s and 1960s must have been as low as they were from 2001 to 2020.

However, examination of pollution data for the North Atlantic reveals that the exact opposite is true: European and U.S. aerosol concentrations in the 1960s were much higher than in any later decade, including decades after 1980 during the study period. This can be seen in the figure below, which depicts the sulfate concentration in London air over the 50 years from 1962 to 2012; similar data exists for the U.S. (see here, for example).

Were the NOAA study valid, such high aerosol levels in European and U.S. skies during the 1960s would have decreased North Atlantic hurricane activity in that period – the reverse of what the data demonstrates in the first figure above. In the Pacific, the study links a supposed reduction in tropical cyclones to a well-documented rise in aerosol pollution in that region, due to growing industrial emissions.

But a close look at the bottom half of the second figure above shows the increase in pollution since 1980 has occurred mostly in southern Asia. The top half of the same figure indicates increased cyclone activity near India and the Persian Gulf, associated with higher, not lower pollution. The only decreases are in the vicinity of Japan and Australia, where any changes in pollution level are slight.

The NOAA study aside, changes in global hurricane frequency are much more likely to be associated with naturally occurring ocean cycles than with aerosols. Indeed, NOAA has previously linked increased Atlantic hurricane activity to the warm phase of the Atlantic Multidecadal Oscillation (AMO).

The AMO, which has a cycle time of approximately 65 years and alternates between warm and cool phases, governs many extremes, such as cyclonic storms in the Atlantic basin and major floods in eastern North America and western Europe. The present warm phase began in 1995, triggering a more tempestuous period when both named Atlantic storms and hurricanes have become more common on average.

Another contribution to storm activity in the Atlantic comes from La Niña cycles in the Pacific. Apart from a cooling effect, La Niñas result in quieter conditions in the eastern Pacific and enhanced activity in the Atlantic. In the U.S., major landfalling hurricanes are tied to La Niña cycles in the Pacific, not to global warming.

Next: Why There’s No Need to Panic about Methane in the Atmosphere

Can Undersea Volcanoes Cause Global Warming?

It’s well known that active volcanoes on land can cause significant global cooling when they erupt, from shielding of sunlight by sulfate aerosol particles in the eruption plume which linger in the atmosphere. But what is the effect on climate of undersea volcanic eruptions such as the massive submarine blast that blanketed the nearby South Pacific kingdom of Tonga with ash in January?

Submarine volcanoes are relatively unexplored but are thought to number over a million, of which several thousand may be currently active. Many lie along tectonic plate boundaries, where plates are pulling apart or colliding with each other. The Tonga volcano sits above a geological pileup, where the western edge of the Pacific plate dives under the Indian–Australian plate.

The eruption of any volcano releases a huge amount of energy. In the case of a submarine volcano that may be thousands of meters deep, the plume may not even reach the surface and all the energy is absorbed by the ocean. The Tonga eruption was from a shallow depth, so much of the energy was dissipated at the ocean surface – launching a destructive tsunami – and in the atmosphere – generating a plume of ash that reached a record altitude of 55 kilometers (34 miles), a shockwave that traveled around the globe, and nearly 400,000 lightning strikes.

You might think all that energy could contribute to global warming, had the volcano erupted in deeper water that would have converted all the energy to heat. However, the oceans, which cover 71% of the earth’s surface, are vast and can hold 1,000 times more heat than the atmosphere. Any change in sea surface temperatures from even multiple underwater volcanic eruptions would be imperceptible.

This can be seen from a simple calculation. According to NASA scientists, the energy released by the undersea Tonga eruption was equivalent to the explosive power of 3.6 to 16 megatonnes (4 to 18 megatons) of TNT. For comparison, the 1980 eruption on land of Mount Saint Helens in Washington state released about 22 megatonnes of TNT equivalent, and the famous 1883 explosion of Indonesia's Krakatoa unleashed 180 megatonnes; the atomic bomb that the U.S. dropped on Hiroshima in Japan in 1945 released roughly 14 kilotonnes of TNT equivalent.

The upper Tonga limit of 16 megatonnes is equal to 7.5 x 10¹⁶ Joules of energy. Assuming the heat capacity of seawater to be 3,900 Joules per kilogram per degree Celsius and the total mass of the oceans to be 1.4 × 10²¹ kilograms, it would take 5.5 × 10²⁴ Joules (5.5 trillion trillion Joules) to warm the entire ocean by 1 degree Celsius (1.8 degrees Fahrenheit).

So if all 16 megatonnes had gone into the ocean, ocean temperatures would have risen by (7.5 x 10¹⁶)/( 5.5 × 10²⁴) or a minuscule 1.4 x 10^-8 (14 billionths) of a degree Celsius. The Krakatoa above-water eruption, on the other hand, decreased global air temperatures by as much as 1.2 degrees Celsius (2.2 degrees Fahrenheit) for several years and may have cooled the oceans as well.

But there’s another potential source of warming from submarine volcanoes, and that is the CO₂ emitted along with the sulfur dioxide (SO₂) that causes cooling through formation of sulfate aerosols. If the underwater plume reaches the ocean surface, both gases are released into the atmosphere. In the case of Tonga, while the amount of SO₂ emitted was too small to have any cooling effect, the emitted CO₂ could in theory contribute to global warming.

However, the yearly average of CO₂ emissions from all volcanoes, both on land and submarine, is only 1 to 2% of current human emissions that have raised global temperatures by 1 degree Celsius (1.8 degrees Fahrenheit) at most. So any CO₂ warming effect from an underwater eruption is unlikely to be much larger than the above calculation for energy release. Interestingly though, Chinese researchers recently reported that the atmospheric concentration of CO₂ near Tonga after the eruption jumped by 2 parts per million, which is as much as the global concentration normally increases in a whole year from human sources. But this is most probably a temporary local effect that won’t affect the global CO₂ increase expected in 2022.

Despite the inability of undersea eruptions to affect our present climate, it was suggested in a 2015 research paper that CO₂ from submarine volcanoes may have triggered the warming that pulled the earth out of the last ice age about 15,000 years ago.

The basic idea is that lower sea levels during glaciation relieved the hydrostatic pressure on submarine volcanoes that suppressed eruptions during warmer times. This caused them to erupt more. After a lengthy ice age, the buildup of CO₂ from undersea eruptions initiated warming that then began to melt the ice sheets covering volcanoes on land, causing them in turn to belch CO₂ that enhanced the warming, melting more ice in a feedback effect.

Next: New Projections of Sea Level Rise Are Overblown

Evidence Lacking for Major Human Role in Climate Change

Conventional scientific wisdom holds that global warming and consequent changes in the climate are primarily our own doing. But what few people realize is that the actual scientific evidence for a substantial human contribution to climate change is flimsy. It requires highly questionable computer climate models to make the connection between global warming and human emissions of carbon dioxide (CO₂).

The multiple lines of evidence which do exist are simply evidence that the world is warming, not proof that the warming comes predominantly from human activity. The supposed proof relies entirely on computer models that attempt to simulate the earth’s highly complex climate, and include greenhouse gases as well as aerosols from both volcanic and man-made sources – but almost totally ignore natural variability.

So it shouldn’t be surprising that the models have a dismal track record in predicting the future. Most spectacularly, the models failed to predict the recent pause or hiatus in global warming from the late 1990s to about 2014. During this period, the warming rate dropped to only a third to a half of the rate measured from the early 1970s to 1998, while at the same time CO₂ kept spewing into the atmosphere. Out of 32 climate models, only a lone Russian model came anywhere close to the actual observations.

Not only did the models overestimate the warming rate by two or three times, they wrongly predict a hot spot in the upper atmosphere that isn’t there, and are unable to accurately reproduce sea level rise.

Yet it’s these same failed models that underpin the whole case for catastrophic consequences of man-made climate change, a case embodied in the 2015 Paris Agreement. The international agreement on reducing greenhouse gas emissions – which 195 nations, together with many of the world’s scientific societies and national academies, have signed on to – is based not on empirical evidence, but on artificial computer models. Only the models link climate change to human activity. The empirical evidence does not.

Proponents of human-caused global warming, including a majority of climate scientists, insist that the boost to global temperatures of about 1.6 degrees Fahrenheit (0.9 degrees Celsius) since 1850 comes almost exclusively from the steady increase in the atmospheric CO₂ level. They argue that elevated CO₂ must be the cause of nearly all the warming because the sole major change in climate “forcing” over this period has been from CO₂ produced by human activities – mainly the burning of fossil fuels as well as deforestation.

But correlation is not causation, as is well known from statistics or the public health field of epidemiology. So believers in the narrative of catastrophic anthropogenic (human-caused) climate change fall back on computer models to shore up their argument. With the climate change narrative trumpeted by political entities such as the UN’s IPCC (Intergovernmental Panel on Climate Change), and amplified by compliant media worldwide, predictions of computer climate models have acquired the status of quasi-religious edicts.

Indeed, anyone disputing the conventional wisdom is labeled a “denier” by advocates of climate change orthodoxy, who claim that global warming skeptics are just as anti-science as those who believe vaccines cause autism. The much-ballyhooed war on science typically lumps climate change skeptics together with creationists, anti-vaccinationists and anti-GMO activists. But the climate warmists are the ones on the wrong side of science.

Like their counterparts in the debate over the safety of GMOs, warmists employ fear, hyperbole and heavy-handed political tactics in an attempt to shut down debate. Yet skepticism about the human influence on global warming persists, and may even be growing among the general public. In 2018, a Gallup poll in the U.S. found that 36% of Americans don’t believe that global warming is caused by human activity, while a UK survey showed that a staggering 64% of the British public feel the same way. And the percentage of climate scientists who endorse the mainstream view of a strong human influence is nowhere near the widely believed 97%, although it’s probably above 50%.

Most scientists who are skeptics like me accept that global warming is real, but not that it’s entirely man-made or that it’s dangerous. The observations alone aren’t evidence for a major human role. Such lack of regard for the importance of empirical evidence, and misguided faith in the power of deficient computer climate models, are abuses of science.

(Another 189 comments on this post can be found at the What's Up With That blog and the NoTricksZone blog, which have kindly reproduced the whole post.)