Ruddiman Plows Annotation of W.F.

¶ … Ruddiman Plows

Annotation of W.F. Ruddiman, Plows, Plagues & Petroleum

Ruddiman's principal claim is that human effect on climate change did not begin in the 1800s as most scientists accept, but began thousands of years before in slow gradual changes whose impact equals that of the Industrial Revolution. He supports this claim in various ways. First, he uses an analogy of the tortoise and the hare to contrast slow vs. rapid changes. Then he shifts into a discussion of the field of climatology and its four revolutions (Hutton on the earth's age and slow change, Darwin on evolution, Wegener on continental drift, and the recent ongoing one) -- all of which establishes his credibility and provides the background premises for his view. He uses crime solving as an analogy for the scientific method he employs. Rhetorically interesting is his use of the analogy of a magician to talk about the misdirection away from more important evidence of gas concentration that occurred before the 1800s. In other words, scientists have been diverted from seeing the real causal connections. Foreshadowing his argument, he says that what ultimately convinced him was the correlation between irrigation and the simultaneous rise in methane, that is, between human history and climate change. This breaks the known trend of a natural law-based cyclic system that he argues must have resulted from human action, not nature. It is all an appeal to logos.

Summary: Chapter one establishes his basic claim and gives background information on the scientific worldview and project that inform his analysis. It establishes him as a credible and trustworthy voice, tempered by reason and not emotion.

Ch. 2, pp. 17-24. His major claim is that for millions of years, pre-humans made no change to earth's climate or environment. His evidence is that pre-humans were too small in number, too mobile, and had no technology that would damage climate. The argument is based first on an evolutionary narrative of human history for which he gives no citation and which he presumes is self-evident. Then he switches to the confirmation, through participatory science and fossil records, of Alvarez's asteroid-impact theory of dinosaur extinction. He introduces a second argument, discrediting other "oceanic gateway" theories, that earth's cooling was the result of drops in CO2 levels, which he supports through the comparison of a volcano to a dripping faucet in a tub -- an effective metaphor that illustrates balance and flux of atmospheric CO2 -- and the geophysical evidence of a decrease in volcanic activity and a corresponding polar cooling. There is a shift from narrative to causal explanation. It is logos-based. His conclusion is that pre-humans for millions of years were not responsible, based on their lifestyle, for climate change.

Summary: He deduces evident that for millions of years, humans had no impact on the earth, using appeals to pathos (astonishment, amazement) and to the logos of the narrative.

Ch. 3, pp. 25-34. Ruddiman's major claim is that the earth's orbit influences climate. Using questions about Agassiz' theory of an "ice age" and evidence for enormous ancient lakes in American and African deserts, he is led to conclude that something has been causing climate change (disappearance of lakes) in short time scales that cannot be slow tectonic changes. He finds the answer in the astronomical theory of the earth's orbit influenced by gravitation. Adhemar's view that changes in earth's orbit should affect the amount of solar radiation reaching its surface (impacting climate) began research that has since explained how axial tilt, eccentricity of orbit (distance from the sun), and precession (wobbling) affect the amount of radiation on earth. These findings are illustrated by charts, arguments, and clarifying analogies such as those of a light bulb and a top that help the reader imagine orbits. Ultimately his claims are based on citation of theoretical findings in astronomy and his descriptive narration of the process of orbit and its effects (process and cause/effect). His ability to tell the scientific narrative establishes credibility (ethos). He achieves balance by presenting opposing viewpoints (seasonal compensation for orbit effects) and pointing out their flaws (over-simplicity, homogeneity).

Summary: Using appeals to scientific advances and acceptance in the scientific community for certain hypotheses, his describes how the earth's orbit can influence the earth's climate.

Ch. 4, pp. 35-45: His main claim is that scientific evidence further confirms the idea of earth's orbit influencing climate. Appealing to the reader's imagination (compare now with past ocean levels), personal example (experience of a snowstorm), and the process of ablation (snow melt), he asserts that winter is not the key to ice sheet control. Citing Milankovitch's hypothesis that summer radiation is the key to ice sheet growth, he points to evidence in radiocarbon dating of ice sheets correlated with data about past levels of summer radiation. Instead of looking at spotty ice sheet data, he looks at evidence in ocean sediment (debris) dropped when ice sheets vanished and oxygen levels in plankton shells. Then he shifts to exemplification, using typical examples from coral reefs and marine sediment that give scientists data for a history of glaciation cycles superimposed on longer-term cooling trends. This evidence points to cycles of glaciations at intervals of 41 or 22 thousand years that are aligned with summer radiation patterns. His argument explains how a process happens and works. He uses the analogy of the freeze and thaw of birdbaths to make it clear. His conclusion is that the earth's orbit controls ice-age cycles. An interesting rhetorical choice at the end is an appeal to imagine what a glacial world would look like -- this is interesting because it is hard to grasp today.

Summary: Using logos and pathos, Ruddiman explores further evidence that orbit controls climate by controlling ice-age cycles.

Ch. 5, pp. 46-54: His primary claim is that monsoon cycles, related to solar radiation cycles from earth's orbit, are another supporting proof that orbit affects climate. He supports this claim with evidence from methane increases during cycles of stronger radiation, and data to refute the opposing view that it was ice sheets. Kutzbach's proposal is advanced, which claims that rain from summer monsoon cycles explains how former wet and green areas (that are now dry) were filled. This is an application of a working climatological model from today into the past. The whole argument is an appeal to logos and process explanations based on the analogy of the past with conditions today. Monsoons and methane levels are correlated because of plant decomposition in water. His conclusion is a mantra: more Sun, more monsoon, more methane. After citing and explaining scientific support, Ruddiman switches to persuasion (opinion) to argue in the first person (self-referential) that gradual orbital-scale changes in climate were not a significant factor in human evolution. Interestingly, he claims non-expertise before giving his view, thus precluding reader's judgment and indicating a shift from "science" to "personal opinion." He thinks abrupt changes are most influential in evolution, but are improvable.

Summary: Ruddiman achieves further support for his orbital view of climate change and adds personal opinions about human evolution on the basis of self-deprecating credibility.

Ch. 6, pp. 55-60: His major claim is that humans, not nature or climate, are the primary cause of the mass mammal extinctions that occurred 12,500 years ago. His narrative of human history is an appeal to pathos (how sophisticated they were). Past glaciations had not wiped out animal populations, so it must be human predation. His evidence is that all past glaciations had the same configuration of climate factors that happened 12,500 years ago, but extinction did not occur. Ruddiman notices that the extinctions happened just as humans moved onto continents. This is an argument from example and correlation, not causation, based on a suggestive time link between climate and history. No similar extinctions occurred in Africa and Eurasia where humans were already co-evolving with animals. He shifts to pathos, appealing to imagination in narrating hunting scenarios that could have led to massive extinction. Then he shifts again to archeological evidence of skeletons at the bottom of cliffs and arrowheads embedded in them, along with population ecology studies showing that mammal species can be extinct rapidly with just slight increases of mortality rates. He knows the fossil record doesn't agree with his theory, but he dismisses it through a pathos appeal to future discoveries. Interestingly, he uses his position to assert opinion ("I will place my bet that . . ."), he uses pathos by mentioning the "tragic chapter" of extinctions and how humans today are over-influenced by Rousseau's view of the noble savage (i.e., they have an unconscious resistance to seeing ancient humans as evil), and he downplays the implication that humans were bad for their actions since it was all survival.

Summary: In this chapter, Ruddiman positions himself to start talking about negative human influence on the environment, illustrating this by the correlation of mammal extinction with the progress of human techniques and rejecting a link between extinction and climate.

Ch. 7, pp. 65-75: Relying on an appeal to the history of agricultural, he describes a hypothetical process by which hunter-gatherers came to abandon nomadism and to settle in farming communities. He describes how wild grains and animals were domesticated, as well as the new technologies that made farming possible (sickles, baskets, pestles, gourds, irrigation, the wheel, the plow). He uses a chart to plot these movements. His evidence is mainly archeological, historical, and botanical with heavy doses of appeal to imaginary scenarios. Its power to convince is narrational. His ultimate point in cataloguing this change is to assert how, for first time in history, humans become a prime factor in altering earth's natural landscapes. Land was now exploited and degraded through deforestation for crops and soil erosion.

Summary: Ruddiman summarizes the history of how humans began to shape the earth through technology and landscape transformation. He relies on the credibility of his narrative.

Ch. 8, pp. 76-83: His main claim is that humans rather than nature have created a rise in atmospheric methane. He presents several lines of argument, beginning with his own explanation of the problem. The anomalous rise in methane cannot be accounted for by natural law since in his detailed investigations tropical and boreal wetlands have shrunk and have not emitted more methane than expected. Citing his own and others' research, he claims the new source generating methane is human farming through such methods as diversion of rivers to irrigate rice (artificially created wetlands), biomass burning (slash-and-burn), livestock emissions, and increased human waste from increased population. Of these, the major factor is irrigation. His main evidence is a correlation between the rise of irrigation use in Southeast Asia (and rise in population) and the methane data burst before industrialization. When his calculating model seems ready to fail, he switches to asserting authority rather than evidence to claim that rice farming was inefficient (more weeds in flooded areas) which meant methane was emitted in excess of the proportion of human population. Realizing how little his opinion is based on facts, he calls for more quantitative evidence, while insisting that the point will be hard to prove. His rhetoric is based on his authority and the weak correlation he draws.

Summary: Ruddiman's point is to try to show how methane gas increases before the industrial era stem from the anthropogenic effects of agriculture, particularly irrigation methods.

Ch. 9, pp. 84-94: The principal claim in this chapter is that deforestation is to blame for pre-industrial increases in atmospheric CO2. First he establishes that CO2 has increased and that it cannot be explained naturally. Claiming lack of expertise, he assesses research into CO2 levels in the ocean that shows the cyclical pattern of climate-based increase and decrease in CO2. Yet he finds the current cycle is different. Taking data from a "high resolution CO2 record spanning the last 11,000 years," he sees levels increasing where they should naturally be dropping. He invokes two natural explanations, discusses only one of them (that extra CO2 came from the natural release of carbon), and dismisses by authority the effort to find natural explanations since all the major climate system factors in the past (radiation, ice sheet retreat, rise in sea level, vegetation change) behaved in same way through the last four intervals of ice melting, yet only the current one shows CO2 rises in the interglacial period. He spends the last part of the chapter explaining a formula, based on William the Conqueror's Domesday Survey in 1089 and scientific evidence of past clear cutting (pollen in sediment, charcoal in soil), to estimate quantitatively whether thousands of years of deforestation could have released the immense amounts of gas necessary to explain CO2 levels. He concludes based on his formula and the data that massive deforestation and burning caused pre-industrial rises in carbon dioxide levels. He ends with an imaginative appeal to seeing a hillside with tamed goats as a natural forest.

Summary: This chapter gives his rational reasons for believing that widespread deforestation could lead to rise in greenhouse gases in the last thousands of years of human civilization.

Ch. 10, pp. 95-105: The main claim in this chapter is that the human-induced increase in greenhouse-gases has delayed the onset of natural glaciation. Global cooling trends (retreat of forests and increase in tundra and sea ice) driven by natural orbital variations has masked global warming in the last 8,000 years. Ruddiman uses William's climate-modeling analysis to show that without this global warming, parts of earth's terrain would be glaciated. His conclusion is that human-based carbon emission has caused higher temperatures that have stalled the natural cooling process. This argument is based on modeled data, scientific theory, and his own view that natural processes cannot explain the change. Then he shifts into a discussion based on his authority of his own simulation of how much cooler the earth would be today without human greenhouse gases. His results are inconclusive.

Summary: This chapter adds further basis for Ruddiman's view of human change of climate through the rhetoric of scientific findings combined with his own interpretations of them.

Ch. 11, pp. 106-114: His claim is that major challenges to his theory do not invalidate it. One challenge called him to look farther back in the sequence of ice-age cycles, which led to him review the ice core data. His review and charts of the new evidence confirm, in his view, the predictive power of his position, although it contradicts the idea that current glaciations is overdue. He finds uncertain additional information that Antarctic temperatures had plummeted to glacial conditions despite the longer interglaciation period, and concludes from reason (not evidence) that the former interglaciation period must have started far earlier than the present one. A second challenge is that ocean warmth means that ice sheets are decreasing, not growing as projected. He rejects this from his own previous studies that say as ice sheets are growing the ocean can stay warm ("lagging ocean warmth") although he admits the reasons for this are unclear. He rejects also the notion that humans could not have slash and burned enough forest to cause such huge gas rises, appealing to his own model in which the prevention of a natural drop in CO2 levels is taken into account to fill the gap. His conclusion is that these challenges do not disprove his thesis. At the end his adds a first person discussion of the way university pressures prevent real reflection and how much time it takes for scientific revolutions to occur -- an appeal from pathos for the reader's patience despite the lack of forthcoming solid evidence. The persuasive effect of this chapter is that it shows the author to be open to responding to criticism, but it does not eliminate the suspicion that he interprets data in the direction of his theory.

Summary: Ruddiman takes on several challenges to his theory and attempts primarily through reason and less through scientific evidence to show how the criticisms are inadequate.

Ch. 12, pp. 119-126: Ruddiman's main claim is that the oscillations (dips) in CO2 levels during the Middle Ages can be explained through natural temporary (not gradual orbit-based) climate variations. He appeals to an analogy of a heating cycle broken by a sudden storm and to imagination of how glaciers would have affected farming. Then he shifts from narrative examples to looks at the natural archives -- tree rings, mountain ice, and coral -- for evidence that a little ice age occurred. He explains the process by which northern regions are cooled through 11-year cycles of variations in sunspots (using satellite and telescope measurements) and how volcanic eruptions cause a cooling effect (sulfuric acid in vapor reflects radiation). He casts doubt on conventional chemical explanations for CO2 drops when it is cooler, saying the models do not explain the rapidity of value drops during stable climate.

Summary: Ruddiman writes this chapter to eliminate the criticism that an ice age appearing in recent history contradicts his view that the globe is warming. His appeal is based on natural cycles and events, and an assertion of his own authority.

Ch. 13, pp. 127-138: This chapter claims that drops in CO2 levels correlate with the human history of disease (pandemics). After claiming no historical expertise, he culls evidence (without citations) from a historical narrative that is presumed to be universally acceptable. He finds no evidence in the historical record (examples) that either war or famine (regressions from agricultural progress) could be responsible for elevated CO2 levels. He plots preindustrial pandemics on a chart with population losses, and compares these with dips in CO2. His conclusion is that there must be a correlation, though not yet causality, between pandemics and dips in atmospheric CO2. The argument rests on the rational premise of a correlation between human history and scientific data.

Summary: This chapter leads into his more detailed discussion of the effects of disease in terms of creating greenhouse gases. It is introductory and based on an inexpert field of his.

Ch. 14, pp. 139-146: Ruddiman's claim is to show the process by which disease may have led to greenhouse gas elevations. He supports this claim through evidence related to increased mortality from disease and its effect on farming such as the abandonment of fields and pastures. In a personal appeal to his experience (his own land), he shows how quickly abandoned fields turn back into forest. This is backed up through ecological evidence that abandoned pastures regain carbon biomass levels of forest in 50 years. He appeals then to the imagination of the audience to envision a scenario in which repeated outbreaks of plague lead to vacant property for years and thus reforestation, the halt of deforestation, and the reduction of coal burning -- all which would lead to increased levels of CO2. Most of these appeals are based on his credibility and reasoning. Interestingly, he flips into a discussion at the end of environmental determinism.

Summary: Ruddiman's argument is that temporary cold intervals in the Dark Age suggest that disease has played a role in global warming (CO2 increases).

Ch. 15, pp. 151-158: His claim is that climate system response lag and aerosol dispersal into the atmosphere explain why post-industrial climate has not had time to register a full temperature response. As evidence, he explains the process of climate system response time using the analogies of heating a cold hot tub and the built-in delay of daytime heating. His discussion involves the explanatory details of how air, land, and water all process temperature changes at different rates. The process for the ocean takes decades, which is important since the ocean is the largest mass influencing earth temperatures and it could take between 30-50 years to fully register these. During explosive periods such as the current industrial era, the registration of climate system response does not keep pace with gas concentration, and therefore the warming that will occur has not been noticed while gas increases have been. This is a rational argument based on scientific models. Further, industrial era emissions, like aerosols, counteract warming and cool the climate. His conclusion is for these reasons temperature rise is unrecorded.

Summary: Ruddiman explains the discrepancy between sizeable increases in greenhouse gases but only small increases in global temperature since industrialization by reference to delayed climate response systems and the counteractive cooling effects from sulfate aerosols.

Ch. 16, pp. 159-168: Switching suddenly to the future, Ruddiman claims that natural resources will be depleted. He bases this claim on Deffeyes' research into peak oil and subsequent decline in oil reserves that result from industrial dependence on carbon-based energies (coal, oil, gas). This is less an appeal to pathos as to logos, but he plays on uncertainties -- what economic choices will be made with these energy forms? He outlines scenarios constructed for future trends in an attempt to make projections for future CO2 levels. Then he weighs in, using authority, with his own opinions and predictions about what effects will occur. He points out slow-responding extremes (such as that Greenland will begin to melt and a warmer ocean may increase ice removal along margins) and fast-responding elements (mountain glaciers will disappear). He guesses about possible future results.