Who ‘Enhanced’ the Greenhouse Effect?
The urgency of Net Zero rests on a 1960s theory that is 1/3 science
In the past few years it has started to sink in that the cost of the proposed energy transition — to Net Zero — is going to be enormous.1
On this, Germany must be the bellwether.
Germany led the way with its Energiewende (‘energy turn’) in 2010.
Its modest CO₂ reductions since have come at the cost of billions and de-industrialization2. Germany is in a nasty recession. It shows few signs of coming out of it any time soon.3
Repercussions from the Energiewende are showing up in German politics, not just the economic data.
The Hitzehammer (‘heat hammer’) — a policy that would have required Germans to convert their homes to heat pumps — became the focus of bitter populist and vaguely alt-right protests in 2022.
In January, the European Council on Foreign Relations said that it foresees, in the upcoming June 2024 European Parliament elections, “populist radical right parties gaining votes and seats across the EU, and centre-left and green parties losing votes and seats.”4
Yet the climate orthodoxy holds that the energy transition can’t wait. Nuclear is too slow. Ratepayer and taxpayer dollars are best spent subsidizing renewables, even if they don’t work very well, because they are faster to build.
It’s worth asking where the urgency comes from.
For that we must pick apart, very carefully, the orthodox belief in greenhouse warming.
That CO₂ is a greenhouse gas is not denied by anyone.
The climate orthodoxy, however, adds a kicker: CO₂ ‘enhances’ the greenhouse effect by increasing water vapor. Water vapor is by far the most potent greenhouse gas.
In a hypothesized feedback loop, air first heated by CO₂ gets warmer. That allows it to takes up more water vapor, which then warms the air still more, leading it to take up more water vapor, and so on.
Yet 60 years after it was first proposed, the ‘enhanced’ greenhouse effect defies empirical observation.
First we should appreciate that the concentration of CO₂ in the atmosphere is ‘significantly variable’.
The quoted phrase is from the opening sentence of Charles Keeling’s seminal 1960 paper reporting his first measurements at Mauna Loa.5
In our current era of science-by-spreadsheet, connection to the real world gets lost. The numbers in internet-downloadable datasets become their own reality.
A CO₂ meter will measure concentrations that varies widely, by hundreds of parts per million (ppm), according to time of day (lower in the morning), wind speed, location (indoors or out), and, most significantly, by season.
NOAA’s PEML Carbon Program has an interesting annotated chart of CO₂ concentration measured at the top of the Seattle Space Needle6:
Those caveats understood, Keeling’s early measurements put the CO₂ concentration at 313 ppm.
The current level — which will no doubt be higher in May — is 419 ppm.
From that, I get an increase of 106 ppm, or 39%.
If the enhanced greenhouse hypothesis is true, the symptoms should be everywhere obvious by now.
They are not.7
It gets worse.
The enhanced greenhouse hypothesis enjoys special protection from falsification in the climate orthodoxy.
Any greenhouse warming that could be blamed on water vapor is ‘really’ the fault of CO₂.
No one disputes that there has been some warming.
So the question the scientists should have been studying is
? → ∆T
Unfortunately, the directive given to the Intergovernmental Panel on Climate Change (IPCC) by the UN was to study ‘climate change … attributed directly or indirectly to human activity’.
Study that and only that.
The IPCC is minimally interested in anything else that could fill in the ? side of the equation.
In the event, UN politicians had already made up their minds about the question mark. It was:
∆CO₂ → ∆T
Maurice Strong, for example, had clearly made up his mind. He was Secretary General of the 1992 Rio UN ‘Earth Summit’.
In his welcoming address, Strong told the delegates: “if CO₂ emissions are not cut by 60 percent immediately, the changes in the next 60 years may be so rapid that nature will be unable to adapt and man incapable of controlling them.”
The IPCC functioned like a legal support staff whose task was to build the UN case against CO₂.
The proposition that CO₂ was a “Principal Control Knob Governing Earth’s Temperature”8 proved to be easy for politicians, the media, and the public to understand.
The ∆CO₂ → ∆T paradigm had another winning attraction: ‘policy relevance’.
CO₂ was (maybe) something ‘we’ could do something about.
If the climate was changing because of the Sun, or volcanoes, or just plain changing, that science result would be seriously disappointing to politicians eager to impose policies that showed they cared about ‘doing something’.
The directive to find anthropogenic warming also explains the Jesuitical distinctions made by the IPCC among 'forcings' and 'feedbacks'.
A ‘forcing’ is a sort of fundamental cause.
Aside: ‘Forcing’ is an unfortunate term, redolent of rape. More subtly, it resonates with old myths about Man being the despoiler of the virginal Garden.
Like diligent advocates making a case, the IPCC looked into ‘natural forcings’ in enough detail —just — to rule them out.
‘Feedbacks’ are secondary effects.
What was called a ‘forcing’ and what was called a ‘feedback’ was basically polemical. Some things, like clouds, seem to be both.
Water vapor was dismissed as a ‘feedback’.
The rock of the orthodox faith was that CO₂ had to be the Prime Mover. What else — of ‘policy relevance’ — could it be?
If that sounds like theology, it is.
In the history of climate science, the enhanced greenhouse hypothesis was first put forward to explain how Snowball Earth might have escaped from extreme glaciation.
This was before Milankovitch’s theory about subtle eccentricities in the Earth’s orbit explained it better.
Volcanic eruptions were hypothesized to have put enough CO₂ in the air to melt the Snowball. A little. Enough for water vapor to kick in and start doing its greenhouse warming thing, in the feedback loop.
In the 1960s, the enhanced greenhouse hypothesis got dusted off.
There had always been some interest in the possible effect of industrial carbon dioxide on the climate.
In the 1960s, numeric models for weather prediction had, at long last, made some progress as computer power increased. Why not try making computer models for the climate?
The focus of these quickly became on estimating something called the Equilibrium Climate Sensitivity, or ECS. That’s a temperature increase from a doubling of the CO₂ concentration in the atmosphere.
In 1960, German meteorologist Fritz Möller came to the US to work with Syukuro Manabe in the then-nascent field of numeric climate modeling.
The best-guess ECS at the time, calculated by Gilbert Plass in 1956, was 3.6° C.
Möller was a true believer. Industrial CO₂ would have a much bigger effect. In 1963, Möller came up with 10° C.
I'll let Manabe describe how Möller did it. Möller’s secret ingredient was water vapor:
An increase in the water vapor content of the atmosphere with rising temperature causes a self–amplifying effect, which results in an almost arbitrary temperature change. For example, when the air temperature is around 15°C, the doubling of CO₂ content results in an increase of temperature by as much as 10°C.9
These were crude models. The computer they had available was an IBM 1401. Manabe did a lot of sketching by hand. Here’s Manabe’s 1967 one-dimensional model:
I have nothing against research scientists making models. To re-write George Box, all models are wrong, but some are interesting. These were interesting. But not exactly what you would use as a basis for energy policy.
The enhanced greenhouse hypothesis lives on, as a sort of zombie theory.
Its scary presence is made known on the high end of the range of ECS estimates produced by the orthodox climate models.
On the basic physics, a doubling of CO₂ —by itself — from 280 ppm to 560 ppm — can be computed to cause, at most, a warming just over 1° C.
That number has gone unchallenged for decades. The IPCC’s number is 1.2°C.
The IPCC goes on to say it believes that an increase in water vapor amplifies that 1.2°C warming into a higher range. In 2021, in AR6, the IPCC said climate sensitivity is likely in the range 2.5°C to 4.0° C.
Let’s use 3° as a midpoint of this range, basically a 3× effect. In his recent book10, Javier Vinós puts this in a nice chart:
Now, 2.5°C to 4.0° C is quite a range.
A question, not original with me, is why 50 years of climate research has not narrowed it down.
That’s actually been the subject of paper in Science: “Why is Climate Sensitivity So Unpredictable?” by Gerard Roe and Marcia Baker, of the Department of Earth and Space Sciences at the University of Washington.11
Roe and Baker’s analysis is thoughtful, but involves a lot of math.
Basically, when you pile on feedbacks in climate models, you mathematically skew them toward worse-case scenarios.
Alarmist outcomes are not an output of the models. They are an input.
Climate model results are not evidence. In the Power Point presentation of their paper, Roe and Baker add a plaintive note:
conclusions come from a modeling perspective
observations of what actually happens have not been used !
As a historian of ideas, I can derive Roe and Baker’s conclusion without the math.
In 2007, MIT atmospheric physicist Richard Lindzen opined that
Future generations will wonder in bemused amazement that the early 21st century’s developed world went into hysterical panic over a globally averaged temperature increase of a few tenths of a degree, and, on the basis of gross exaggerations of highly uncertain computer projections combined into implausible chains of inference, proceeded to contemplate a roll-back of the industrial age.12
I here offer my take on how it came about, for the benefit of future generations.
An unfortunate coincidence of events
Climate is basically chaotic. But there are such a thing as ‘stochastic trends’, a sort of wandering, but not entirely random, behavior.
On short enough time scales, these can easily be mistaken for simple deterministic trends.
Among the many things going on in climate are climate regimes. These are multi-decade (say, 20- or 30-year) shifts of ocean heat transport. They are are often punctuated by large El Niño events.
There was a major turning point in the Earth's climate in 1976.13 This kicked off a regime of warming after the cooling period between 1945 and 1975:
That 1976 shift came in ‘interesting times’, politically and culturally.
The 1974 OPEC oil embargo had pulled the emergency brake cord on the comfortable post-World War II economic expansion.
A widely held view, dating back to Marx in the 1850s, was that capitalism had a ‘growth imperative’. Capitalist economies had to expand or die.
To some, the oil crisis was not just about the advanced economies hitting a speed bump.
Capitalist expansion was asymptotically approaching some fundamental limit: peak oil, peak whatever.
This was the thesis of The Limits to Growth: A Report for the Club of Rome's Project on the Predicament of Mankind, which appeared in 1972.
The timescale in The Limits to Growth interestingly prefigures that of the climate debate: “the limits to growth on this planet will be reached sometime within the next one hundred years. The most probable result will be a rather sudden and uncontrollable decline…”14
Capitalism’s growth imperative was also, for many, the root cause of the environmental depredations of the era. Growth requires additional material inputs, hence more extraction, more exploitation and spoilage of nature.
In time since, ‘sustainability’ has become an uncontroversial, if somewhat vague, mantra based on that notion. ‘Sustainability’ implies some kind of throttling back. What is ‘sustainable’ and what is not is, of course highly political.
Some fringe ideas, notably ‘degrowth’, went farther. The French term, décroissance (literally, ‘decay’), was coined in 1972 by New Left philosopher André Gorz.
Deprived of growth, capitalism would decay. ‘Degrowth,’ according to a now-archived website, “is a critique of the global capitalist system which pursues growth at all costs, causing human exploitation and environmental destruction.”
It’s worth noting that the politicians and policy-makers who were in charge of things during the next decades came of age when this heady intellectual stew was in the air.
Rajendra Pachauri (b. 1940), for example, told Nature in an interview:
We have been so drunk with this desire to produce and consume more and more whatever the cost to the environment that we're on a totally unsustainable path. I am not going to rest easy until I have articulated in every possible forum the need to bring about major structural changes in economic growth and development. That's the real issue. Climate change is just a part of it.15
Rajendra Pachauri is not a household name. But he was the UN functionary in charge of the Intergovernmental Panel on Climate Change from 2002 to 2015.
It’s unclear what ‘major structural changes’ Pachauri was talking about.
Pachauri, who died in 2020, was presumably not a proponent of ‘degrowth’.
Yet in Germany, degrowth appears to be precisely what the rush to decarbonize is delivering.
For less serious take on CO₂, try mine here.
See the Financial Times, “EU must invest about €1.5tn a year to meet Net Zero targets, says Brussels”, 23 January 2024. (link $). The EU goal is a 90% emissions reduction by 2040. For the world as a whole, see Bloomberg, “$200 Trillion Is Needed to Stop Global Warming. That’s a Bargain”, 7 July 2023 (link $).
Modest: German in-country emissions declined 2% in 2022. Some of that came by importing electricity from Denmark and France. French electricity is 67% nuclear. Billions: In late 2018, Germany’s Federal Court of Auditors put the cost of the Energiewende at €160bn for (only) the previous 5 years. The Court’s President noted the expense was “in extreme disproportion to the results.” Quoted in Der Spiegel, May 13, 2019. On de-deindustrialization see, among many, “Rust Belt on the Rhine,” Politico EU, July 13, 2023 (link) .
The German economy officially entered recession in January 2023. For its prospects, see CNN, “Europe’s biggest economy shrank last year. The outlook isn’t much better”, 15 January 2024 (link). Also Fortune, “Europe’s largest economy, struggling to pull itself out of recession, hit with rail strikes and farmers’ protests to start 2024”, 12 January 2024 (link $).
European Council of Foreign Relations, “A Sharp Right Turn: A Forecast For the 2024 European Parliament Elections” January 2024. (link).
Keeling’s paper “The concentration and isotopic abundances of carbon dioxide on the atmosphere” was published in a journal called Tellus in June 1960 (Volume 12, Number 2).
Empirical observation: Climatology is not an experimental science, which makes it difficult to test hypotheses. This creates a debate pattern has become familiar, and is unfortunate. A hypothesis, perhaps supported by a computer model, is put forward that confidently predicts a trend -- or, more difficult to discern, an 'increasing' trend. The media loves talking about trends. It reports this.
What then follows, drip-by-drip, are observational studies by scientists who go looking for the trend, but can’t find it, at least to any statistical significance. Finding 'no trend' doesn’t make the news.
Roger Pielke, Jr., for example, has been locked in this debate pattern for years, fighting the good fight over the (statistically untrue) assertion that hurricanes are on an upward trend.
A sampling of many water vapor studies by topic:
Humidity, precipitable water vapor, and total precipitable water content
• “no robust trend in global water vapor data” [Haar et. al.]
• “our RH [relative humidity] reconstruction shows no significant centennial trend from the 1820s through the 2000s.” [Shi et al., 2018]
• “atmospheric temperature and water vapor trends do not follow the conjecture of constant relative humidity over North America” [Jih-Wang Wang, Roger Pielke Sr, 2008]
Precipitation and extreme precipitation
• no “detectable and significant positive trends in the amount of global precipitation due to the now well-established increasing global temperature.” [Nguyen et al., 2018]
• “Also not significant are the trends in extreme precipitation” [Depietri and MacPhearson, 2018]
• “In contrast to the projected increase in extreme precipitation, there is no robust change in precipitation totals on the global scale.” [Tabari and Willems, 2018}
Hydrological cycle generally:
• “no detectable global-scale human influence on the Earth’s hydrological cycle” [Miralles et. al., 2013]
The ‘control knob’ meme dates to a 2010 essay in Science by Andrew A. Lacie, “Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature.” (link). The climate models actually have a second control knob, aerosol cooling, which allows them to be tuned to overfit the data from any particular time span.
Syukuro Manabe and Richard T. Wetherald, “The Effects of Doubling the CO2 Concentration on the climate of a General Circulation Mode”, 01 Jan 1975 (DOI).
Javier Vinós, Solving the Climate Puzzle: The Sun's Surprising Role, Critical Science Press, 2023.
Gerard H Roe and Marcia B Baker, “Why is climate sensitivity so unpredictable?”, Science 26 Oct 2007 (DOI).
Lindzen wrote this in 2007 as a cover blurb for a book by Christopher C. Horner, The Politically Incorrect Guide to Global Warming and Environmentalism.
It took scientists some time to notice what happened in 1976. By 1991, a study had tallied up drastic shifts in 40 environmental variables in the Pacific climate that year. These included air and water temperatures, the Southern Oscillation, chlorophyll, geese, salmon, crabs, glaciers, atmospheric dust, corals, carbon dioxide, winds, ice cover, and transport through the Bering Strait, etc. See Javier Vinós, above, p. 306.
The quote is from Conclusion One of The Limits to Growth. The text of the 1972 book is available on a website dedicated to the work of the Meadows, the husband-and-wife team who were the primary authors (link).
The Pachauri quote is from a “Newsmaker of the year” profile by Gabrielle Walker which appeared in Nature 19, December 2007.