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Review of ‘Introduction to Modern Climate Change’ by Andrew Dessler (Part II: Physical Science)

By Robert Bradley Jr. -- August 22, 2019

This continues my three-part review of Andrew Dessler’s primer on the physical science and political economy of climate change, Introduction to Modern Climate Change (2nd edition: 2016).

Part I, “Suggestions for More Interdisciplinary Scholarship, Less Advocacy,” brought attention to the uneven treatment of issues in science, economics, and public policy that tainted the primer. I questioned the Deep Ecology assumption of optimal nature, wherein, according to Dessler, “any change in climate, either warming or cooling, will result in overall negative outcomes for human society” (p. 146).

This seems exactly wrong in our interglacial period when climate-related fatalities have fallen dramatically and agricultural production has soared thanks to warmth but particularly to fossil-fueled capitalism. Incentives and wealth have proven more than a match for the vicissitudes of weather and climate. As Alex Epstein (The Moral Case for Fossil Fuels, pp. 126-127) noted:

The popular climate discussion has the issue backward. It looks at man as a destructive force for climate livability, one who makes the climate dangerous because we use fossil fuels.

In fact, the truth is the exact opposite; we don’t take a safe climate and make it dangerous; we take a dangerous climate and make it safe. High-energy civilization, not climate, is the driver of climate livability.

Science issues which caught my eye follow.

Climate Sensitivity. Why is real-world warming lagging behind model-predicted? [1] Are climate models beyond reproach? Dessler mentions models as reliable for laboratory-like experimentation (p. 117), which is highly disputable given “fudge factors,” ex-post tuning, and validation limitations. The 3rd edition should examine the critics’ arguments (including from Dessler’s colleague Gerald North) against climate-model reliance and prediction.

What might be responsible for lower climate-sensitivity estimates? Listing and discussing the possibilities is missing from the first two editions. Here are two:

1. Iris Effect Richard Lindzen’s Iris Effect is a mechanism for trapped heat to escape in the Tropics, reducing anthropogenic warming. Is this a physical impossibility? If not, does it have evidence to be partially right, a reason for global lukewarming?

This hypothesis has attracted support in mainstream science. Dessler has rejected it elsewhere as small. But small effects can scale back the alarm, and who dare say it cannot be more of a countervailing feedback than is known at present?

2. Indirect Solar Effects Dessler presents the direct and “highly uncertain” (p. 99) indirect effects of aerosol forcing (pp. 95–100). But when it comes to solar, he criticizes direct solar as a major source of forcing (p. 100–101; 113–114) but is silent on the indirect effects of solar forcing.

If indirect solar as an alternative explanation for climate change a theoretical impossibility or without evidence, Dessler should state such. But if it is an open area, and it appears to be (also see here), the hypothesis of indirect forcing as a climate driver should be sympathetically presented and rigorously evaluated.

Warming Distribution. A long-time argument against climate alarmism was the distribution of the identified anthropogenic warming. Evidence was that minimum temperatures were increasing at twice the rate of maximum temperatures (a reduced diurnal cycle). Winters were warming more than summers, also reducing temperature variability.

Warmer winters? And not so much summer temperature increases? That all sounds good to a climate economist and for a livable, robust climate. But this happy argument quietened among skeptics. In fact, the latest IPCC report [5th Ass. (2014), Working Group I: p. 188] walked back those findings.

But Dessler states all of these things (as if he did not review the 2014 report), concluding, “adding greenhouse gases to the atmosphere tends to reduce temperature contrasts” (p. 148). An indication where the IPCC will land in the future (the 6th assessment is due out in 2021) is another important area of unsettled science.

Positive Surprises

Dessler states: “The Earth is currently in an interglacial” (p. 36). This throw-away fact is actually pregnant with implication. If we are in a (lucky) warming period, might CO2 concentrations at some point forestall a natural cooling period for the benefit of mankind? This “surprise” would be a huge positive, a fat tail of joy and celebration.

Dessler is certainly thinking ahead. “Even after emissions cease, the temperatures do not significantly decline over the next 1,000 years” (p. 138). And more, “emitting large amounts of carbon dioxide to the atmosphere this century commits the planet to elevated temperatures for thousands of years” (ibid. 138).

If correct, this can be appreciated as an insurance policy against the chance of a Little Ice Age or Ice Age. And given my disagreement with Dessler’s belief that in the next decades “greenhouse-gas emissions [fossil-fuel combustion] will eventually cease because of concerns about climate change or because technological developments make fossil fuels obsolete” (ibid), I see this insurance policy for millenia. [2]

Saturation Effect: Log Forcing

The forcing property of the enhanced greenhouse effect is not linear but logarithmic, meaning that the warming from a doubling of CO2 will not happen at a tripling but with a quadrupling. Seen another way, the greater atmospheric concentration of CO2 (measured in parts per million), the less warming additional PPMs create.

This is a blow to Mitigation given that avoided emissions have less and less effect, requiring more and more cutbacks to achieve the desired effect.

The log-over-linear property of greenhouse-gas forcing receives nary a mention in the 2nd edition. It is part of the public policy argument of Mitigation relative to Adaptation and should be considered as such in the 3rd edition.

CO2 Fertilization: The Benefit Side of the Equation

Relatively settled science points toward the positive ecological effect of higher atmospheric CO2 concentrations. Dessler mentions photosynthesis (pp. 69–70) and the “missing carbon” (p. 79), but he buries a vital issue of the climate debate in a footnote on page 153:

One frequently hears that increasing carbon dioxide will be good for plants – i.e., “carbon dioxide is plant food.” Atmospheric carbon dioxide is indeed a key ingredient in plant growth and, everything else being equal, more carbon dioxide in the atmosphere would be expected to increase the rate of plant growth. However, other changes, such as changes in temperature and precipitation, are expected to offset the benefits of increased carbon dioxide, particularly the warming of more than a few degrees Celsius.

How much benefit and for what plant types? For how long? And contra-Dessler, peer-reviewed research is that higher CO2 makes many plants adapt to higher temperatures and become more water-efficient (the CO2 Coalition has documented this and other benefits).

CO2 fertilization, as well as the positive effect of moderate warming and higher precipitation, impress climate economists of the benefit side of CO2 emissions. Dessler focuses on the social cost of carbon in this book (p. 171–174) but neglects CO2’s benefits that occur sooner and thus carry more weight in any cost/benefit exercise. (The Obama Administration unfairly assessed the social cost of carbon without including the benefit side of the equation).

Judith Curry

Dessler directs the reader for “further reading” to SkepticalScience.com. Why not also mention Climate Etc. by Judith Curry? She is highly credentialed, traffics in peer-reiewed science, gives voice to important “skeptic” arguments ignored elsewhere, and calls out exaggerated and unfounded arguments. Her work is widely read and very influential.

The student should be exposed to the best arguments on each side. Is Dessler afraid that his readers cannot think for themselves? In fact, students need to go straight to the source for opposing views and go back and forth to get answers in the highly contentious, polarized climate debate.

Two False Alarms

Dessler’s primer will have to drop a few things, which should inspire the question: what might be dropped–and introduced–in the next revision?

The author mentions “the extinction of the polar bears” (p. 237), a seemingly appropriate example of the economic value of a threatened species from climate change. But the most recent evidence is that polar bear populations are increasing. Resilience and adaptation are major themes that this example (and another, the coral reefs in a warming world) need to be appreciated.

Dessler in the 3rd edition also needs to drop his peak-oil nostrums (“fossil fuels will be exhausted in the next century or so” p. 235) as a we-have-to-do-it-anyway argument. His lone reference to future oil supply is Kenneth Deffeyes discredited Beyond Oil (2006). In its place, Resourceship should be mentioned as the refutation of Peak Oil, elevating the economics/business view of supply over the natural-science view of fixity/depletion.

No doubt Dessler will showcase Hurricane Harvey as anthropogenic climate change in the 3rd edition. (Weather extremes du jure are seized upon as either proof of climate change or what we can expect from present/future climate change.) One only hopes that in addition to warming, he explains the highly unique weather pattern that stalled the storm, the history of Houston flooding, and the very small loss of life due to fossil-fueled wealth-is-health (106 in the US compared to Galveston’s Great Storm of 1900, responsible for 8,000).

Part III in early September will examine energy, history, and policy issues to complete this review.


[1] The iconic graph below, updated as necessary, should be sympathetically presented and rigorously evaluated by Dessler in the 3rd edition–as if its author (John Christy) was in the room.


[2] My disagreement stems from the fundamental requirement of energy density in light of the open-ended mineral resource future. Geoengineering could well come into play, if needed, in a future century.

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