Below please find page notes for The Cartoon Introduction to Climate Change. This is a working document, so additions or edits are welcome! Also note that occasional Wikipedia references are for topics that can be found in many introductory textbooks.

Chapter 1: Introduction (pages 3-14)

Page 4, “Story #1 is about economic growth”: An interesting read here is Bill Gates’s take-down of the myth that “poor countries are doomed to stay poor”.

Page 4, the invisible hand: The “invisible hand” idea is that individual self-interest can (“as if led by an invisible hand”) lead to economic growth and otherwise promote the common good. The metaphor comes from The Wealth of Nations (1776) by Adam Smith, who was a Scottish philosopher and “the father of modern economics”. For more on this see our Cartoon Econ books, especially Volume One: Microeconomics.

Page 5, world population: See the amazing chart in “U.N. Forecasts 10.1 Billion People by Century’s End” (NY Times, May 3 2011). Note that the UN has released a new World Population Prospects. The “medium variant” shows population rising from 7 billion in 2010 to 8 billion in 2025, 9 billion in 2040, 10 billion in 2065, and 10.9 billion and still rising (albeit very slowly) in 2100.

Page 5, “a world of 2-6 billion”: This refers to an article by demographer Wolfgang Lutz, “Towards a world of 2–6 billion well-educated and therefore healthy and wealthy people” (Journal of the Royal Statistical Society, 2009).

Page 9, “alien planet”: This is an allusion to Harvard economist Marty Weitzman: “Societies and ecosystems whose average temperature has changed in the course of a century or so by ΔT > 6°C (for U.S. readers: Δ6°C ≈ Δ11°F) are located in the terra incognita of what any honest economic modeler would have to admit is a planet Earth reconfigured as science fiction, since such high temperatures have not existed for some tens of millions of years.” From Martin L Weitzman, “A Review of The Stern Review on the Economics of Climate Change, Journal of Economic Literature 45:703-724 (2007).

Page 9, “wicked problem”: Believe it or not, “wicked problem” is a technical term. So is “super wicked problem”!

Page 12, “Seattle in July”: Thanks to Washington State’s Assistant State Climatologist Karin Bumbaco for helping out here; the temperature range given is based on the mean Seattle Sandpoint July temperature +/- one standard deviation over the period of record. On flowers blooming earlier, see Observed Changes in Phenology Across the United States – Pacific Northwest: “Across the Northwestern and interior Western U.S. time of first bloom for lilac (Syringa vulgaris) and honeysuckle (Lonicera tatarica and L. korolkowii) showed a trend toward earlier flowering (average advances of 7.5 days for lilac and 10 for honeysuckle) over an almost 40-year period.”

Page 12, “climate is like your personality, weather is like your mood”: There are other, similar comparisons, e.g., “climate is what you expect, weather is what you get” and “Climate tells you what clothes to buy, weather tells you what clothes to wear.” I’m not sure where the personality/mood comparison comes from, but I first came across it in a 2013 TEDx Atlanta talk by Marshall Shepherd, president of the American Meteorological Society, on “Slaying the ‘Zombies’ of Climate Science”.

Chapter 2: A brief history of Planet Earth (pages 15-26)

A good general reference for this chapter is David Catling’s Astrobiology: A Very Short Introduction (2014). Professor Catling also recommends these two books: Ruddiman’s Earth’s Climate: Past and Future (2nd ed., 2008) and (a bit more technical than Ruddiman’s) Kump, Kasting, and Crane’s The Earth System (3rd ed., 2009).

Page 15, “first the Earth cooled”: The line comes from the 1982 disaster spoof movie Airplane II: The Sequel:

Steve McCroskey: Jacobs, I want to know absolutely everything that’s happened up till now.

Jacobs: Well, let’s see. First the Earth cooled. And then the dinosaurs came, but they got too big and fat, so they all died and they turned into oil. And then the Arabs came and they bought Mercedes Benzes…

The sequel received mediocre reviews, but the original movie from 1980, called Airplane!, is regarded as surely one of the funniest movies of all time. (And don’t call me Shirley!)

Page 17, photosynthesis: More here. Note that not all photosynthesis is done by green things; for example there’s brown algae, such as kelp, red algae, etc.

Page 18, carbon cycle: See AR5 WG1 Figure 6.1 (IPCC 2014). Older figures include this NASA graph, this more complicated figure from AR4 WG1 Figure 7.3 (IPCC 2007), and this from NOAA.

Page 18, “mostly water and carbon”: By mass, the human body is about 53% water and 18% carbon. (We assume cows are similar.) Water seems to make up 50% or more of total plant weight, and in terms of dry-weight (i.e., besides the water) plants are about 50% carbon.

Page 19-21, ozone: Ozone exists in the atmosphere at two levels, both as the ozone layer (aka “stratospheric ozone” or “good ozone”), which occurs naturally in the layer of the upper atmosphere called the stratosphere, and as ground-level ozone (aka “troposheric ozone” or “bad ozone”), which contributes to smog and is mostly produced by cars and other human activities. More here on the ozone hole, which refers to the depletion of “good ozone” from the ozone layer.

Page 22, Snowball Earth and tropical North Pole: See more here about the Snowball Earth hypothesis. As for a tropical North Pole, see the Paleocene–Eocene Thermal Maximum (PETM) about 55 million years ago; see also “Studies Portray Tropical Arctic in Distant Past” (NY Times, June 1 2006).

Page 23, Carboniferous Period: See here, plus lots of other cool articles and images from the BBC, National Geographic, and the University of California Museum of Paleontology.

Page 24, continental drift: See this 2012 NPR story. Continental drift (and fingernails) grow at about 1 inch per year.

Page 24, “species either died off or slowly evolved into the forms they have today”: Professor Catling (see above) notes that almost all of them (99%-ish) died off.

Page 25, glacial periods and ice ages: According to some technical definitions, Earth has been in an “ice age” since the ice sheets of Antarctica formed 2.6 million years ago. In common usage, however—and in the language of the IPCC—“ice age” refers to periods (such as 20,000 years ago) when there were extensive Northern hemisphere glaciers; we’ll discuss this more in the next chapter!

Page 26, “human beings appeared in Africa”: See anatomically modern humans.

Page 26, “I wonder what caused the ice ages?”: Evidence came from scratches in rocks (called glacial striations, which can be found, e.g., in what is now New York City’s Central Park; see “The Very Cold Case of the Glacier”, NY Times, Sept 14 2005) and glacial erratics, including those identified by Charles Darwin and Louis Agassiz.

Chapter 3: The ice ages (pages 27-38)

Page 28, “there must have been ice ages”: See for example the studies of Louis Agassiz. A good book is Imbrie and Imbrie, Ice Ages: Solving the Mystery (1986); the elder Imbrie was a co-author of the famous 1976 paper in Science called “Variations in the Earth’s Orbit: Pacemaker of the Ice Ages”. Another good book is Richard Alley’s The Two-Mile Time Machine (2000).

Page 29, “ice cores”: Scientists can determine a tremendous amount of information from ice cores by studying the air bubbles trapped in them and the chemical composition of the ice itself (e.g., the prevalence of different isotopes of hydrogen and oxygen). The temperature graph we use comes from AR5 WG1 Figure 5.3 (IPCC 2014). See also Rahmstorf et al., 2004, “Cosmic Rays, Carbon Dioxide, and Climate”, Eos 85(4), based on Petit et al., 1999, “Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”, Nature 399: 429-436.

Page 30-31, Milankovitch: More on Milutin Milankovitch and the Milankovitch cycles. We focus on the cycle that’s easiest to understand, the 41,000 year cycle in the tilt of the earth. There are also cycles that affect the eccentricity of the Earth’s orbit (the extent to which the orbit is circular versus elliptical) and the Earth’s precession (which related to the the fact that the earth wobbles like a top, meaning that in 3200 years a different star will be the “North star”). There is a common misconception that it is the Earth-Sun distance (i.e., eccentricity) that causes winters and summers, but this is actually a minor factor; if it was the major factor then both hemispheres would experience winter at the same time and summer at the same time. In fact the major cause of winters and summers is tilt, which is one reason we focus on it in the book.

Page 32, “like a pacemaker”: The reference is to the famous research paper that provided definitive evidence that Milankovitch was right: Hays et al., 1976, “Variations in the Earth’s Orbit: Pacemaker of the Ice Ages”, Science 194: 1121-1132.

Page 34-37, “imagine we’re in Canada”: The Milankovitch theory actually focuses on whether Northern Hemisphere summers are strong or weak. Winters don’t matter so much because it’s always cold enough for snow in Canada and Siberia, and the Southern Hemisphere doesn’t matter so much because most of the Earth’s land mass is in the north. (See Chapter 4.)

Page 38, “Mother Nature is gearing up for another ice age”: See AR5 WG1 Chapter 5 (IPCC 2014, page 387): “Climate models simulate no glacial inception during the next 50,000 years if CO2 concentrations remain
above 300 ppm.” See also AR4 WG1 Chapter 6 (IPCC 2007): “It is virtually certain that global temperatures during coming centuries will not be significantly influenced by a natural orbitally induced cooling. It is very unlikely that the Earth would naturally enter another ice age for at least 30 kyr [i.e., 30,000 years].” This is roughly in line with the last sentence of the famous paper cited above, Hays et al., 1976: “…the long-term trend over the next 20,000 years is toward extensive Northern Hemisphere glaciation and cooler climate.” The “20,000 years” part was conveniently overlooked in a climate-skeptic column by George Will (“Cooler Heads Needed on Warming”, April 2, 2006) that argued that scientists in the 1970s were warning of “extensive Northern Hemisphere glaciation.” Not only did Will overlook the 20,000 years angle, he also ignores the caveat that Hays et al. added: “Such forecasts… apply only to the natural component of future climatic trends—–and not to such anthropogenic effects as those due to the burning of fossil fuels.”

Chapter 4: Carbon dioxide (pages 39-50)

Page 40, “what we call air”: The composition of the air is given here or here or in any atmospheric chemistry textbook. The fact that air is 78% nitrogen is celebrated every April on Nitrogen Day at my alma mater, Reed College (in Portland, Oregon).

Page 40, “molecules of CO2 in every breath you take”: We assume 1 x 10^22 gas molecules in each breath. (See also here for an interesting twist, but note that it assumes 2 x 10^22 gas molecules in each breath.) As noted, air is 21% oxygen and about 400 parts per million CO2, i.e., 0.04% CO2, so 0.04% of 1 x 10^22 is 4 x 10^18. Also note that the percentages we list are actually for dry air; water vapor content ranges from 0-3%, with the atmosphere-wide concentration averaging around 1%.

Page 41, Keeling: Lots more at the Scripps CO2 webpage, including his biography and the first published Keeling curve, from 1960. Note that measuring was (and still is!) done on Mauna Loa in Hawaii because 13,000 feet elevation in the middle of the Pacific Ocean is a good place to sample air without having to worry about the effects of local factories or cars. Visit this website for the latest Keeling Curve data as well as historical data.

Page 44, “1ppm equals about 2 billion extra tons of carbon or almost 8 billion extra tons of CO2″: Oak Ridge National Lab says that 1ppm is 2.13 billion tons of carbon, and since 1 ton of C equals 3.67 tons of CO2 that’s 7.82 billion tons of CO2. (As noted in the glossary, carbon has an atomic mass of 12 and oxygen has an atomic mass of 16, so CO2 has a molecular mass of 12+32=44; that’s why 1 ton of C equals 44/12=3.67 tons of CO2.) Note that scientists split between talking about C and CO2, so it’s important to keep track of which one is being used. Economists tend to talk about “carbon taxes” being levied per ton of CO2, but occasionally you will see taxes per ton of C, in which case keep in mind that a tax of $x per ton CO2 is 3.67 times more than a tax of $x per ton C, i.e., a tax of $1.00 per ton CO2 is equivalent to a tax of $3.67 per ton C.

Page 46, CO2 emissions: See my CO2 spreadsheet, with sources and additional details from AR5 WG1 Figure 6.8 (IPCC 2014). In particular, fossil fuel emissions are from CDIAC at Oak Ridge National Labs. (Note that IPCC and CDIAC data are in million metric tonnes of C; multiply by 3.67 to get million tons of CO2.) For gallons of petroleum every second, EIA estimates 87.5m barrels per day; note that there are 42 gallons in a barrel. On forest covering 1/3rd of the Earth’s land surface, see FAO’s Global Forest Resources Assessment 2010.

Page 47, carbon cycle: As on page 18, see AR5 WG1 Figure 6.1 (IPCC 2014). Older figures include this NASA graph, this more complicated figure from AR4 WG1 Figure 7.3 (IPCC 2007), and this from NOAA.

Page 48, ice cores: As in Chapter 3, the graphs come from AR5 WG1 Figure 5.3 (IPCC 2014). See also Rahmstorf et al., 2004, “Cosmic Rays, Carbon Dioxide, and Climate”, Eos 85(4), based on Petit et al., 1999, “Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”, Nature 399: 429-436.

Chapter 5: Energy (pages 51-62)

Page 52, “global average temperature”: See the entry in the AR5 WGI Glossary (IPCC 2014) for “energy budget” for current global average temperature of 15 °C.

Page 54, “picture the sun as a basketball”: At one point in time there was a picture on Wikipedia, but apparently no more; fortunately, we can do the math ourselves: A basketball has a circumference of about 0.755m, so divide by 3.14 (pi) to get a diameter of about 0.24m. The sun has a diameter of about 1.4 x 10^9m, so to turn it into a basketball you divide by 5.8 x 10^9. The Earth has a diameter of about 1.3 x 10^7m, so divide by 5.8 x 10^9 to get about 0.002m, i.e., about 2mm. The Earth-sun distance is about 1.5 x 10^11m, so divide by 5.8 x 10^9 to get about 26m, which is about the length of an NBA court.

Page 55, “energy from the Sun”: See this solar radiation spectrum, from Wikipedia.

Page 56, “albedo”: See AR5 WG1 Section 1.2.2 (IPCC 2014, p126): “The fraction of SWR [solar shortwave radiation] reflected back to space by gases and aerosols, clouds and by the Earth’s surface (albedo) is approximately 30%.” For a complete picture of energy in and energy out, see AR5 WG1 Figure 2.11 (IPCC 2014). On a technical note, climate scientists sometimes separate the energy equation into the net solar input (in minus out) and the Earth radiation out, so that reflected solar energy is subtracted from Energy In rather than added to Energy Out; both ways are of course correct.

Page 57, “radiation given off by the earth”: A good graphic is the “Sun and Earth Radiation Spectrum” from here, but note that both axes are using log scales. (That means, for example, that you can’t just look at the areas under the curves to estimate quantities of Energy In and Energy Out.)

Page 57, “thermal imaging equipment”: We originally referenced night-vision goggles, but learned—thanks to commenter JK—that the typical “green image” goggles actually use light amplification rather than thermal imaging. Here’s a super-cool comparison video.

Page 58, “greenhouse gases”: See the entry in the AR5 WGI Glossary (IPCC 2014) or here.

Page 59, “reducing energy out”: Note that all of these are examples of reducing energy out, but they don’t work in exactly the same way, e.g., greenhouses do not reduce energy out by blocking outgoing longwave radiation. Some folks think the “greenhouse effect” should therefore be renamed (perhaps to the “smudgepot effect”) but IMHO the name is fine as long as you remember that the analogy refers to reducing energy out and not to the specific mechanism by which that reduction takes place. Also note that many people avoid this issue by saying “heat-trapping gases” instead of “greenhouse gases”.

Page 60, “by the 1800s”: See here for more on Fourier, etc. See also this NOAA FAQ on the greenhouse effect: “Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C).” (Note that on page 52 we say that the current global average temperature is 15°C, based on the entry in the AR5 WGI Glossary (IPCC 2014) for “energy budget”. Here on page 60, though, the scientists are talking about the global average temperature in the 1800s, not the present day.)

Page 60, Venus: See a planetary sciences textbook, or Wikipedia, which says that Venus “has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet’s surface is 92 times that of Earth’s. With a mean surface temperature of 735 K (462 °C; 863 °F), Venus is by far the hottest planet in the Solar System.”

Page 62, Arrhenius: See Section V (and in particular Table VIII) of Arrhenius 1896, “On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground”, Philosophical Magazine and Journal of Science, Series 5, Volume 41, April 1896, pages 237-276. This concept is now known as equilibrium climate sensitivity, and AR5 WG1 Section TS.5.3 (IPCC 2014, page 81) says that it is “likely in the range 1.5°C to 4.5°C”.

Chapter 6: Science (pages 63-74)

Page 63, scientific method: Lots more on the scientific method and its history.

Page 64, “at very high speeds”: Here’s a nifty reading on GPS and relativity.

Page 68, smoking: See the 1964 report Smoking and Health: Report of the Advisory Committee of the Surgeon General of the Public Health Service. In particular, page 7 notes that “Surgeon General Leroy E. Burney issued a statement on July 12, 1957, reviewing the matter and declaring that: “The Public Health service feels the weight of the evidence is increasingly pointing in one direction: that excessive smoking is one of the causative factors in lung cancer.”” And page 31 notes that “Cigarette smoking is causally related to lung cancer in men; the magnitude of the effect of cigarette smoking far outweighs all other factors. The data for women, though less extensive, point in the same direction.” For the 2004 report, see The Health Consequences of Smoking: A Report of the Surgeon General (May 27, 2004). Also note that a more recent Surgeon General report came out in 2014 (The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General, 2014) and said that smoking is also linked to diabetes, colorectal cancer, liver cancer, erectile dysfunction, and ectopic pregnancy.

Page 68, global warming: The quotes come from SAR [AR2] WG1 (IPCC 1995), which says that “the balance of evidence suggests [optional: that there is] a discernible human influence on global climate”; from TAR [AR3] WG1 (IPCC 2001), which says that “[t]here is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities”; and from AR5 WG1 SPM (IPCC 2014, page 17), which says: “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

Page 68, smoking and global warming: A book recommended by a colleague (I haven’t read it): Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming by Naomi Oreskes and Erik M. M. Conway (2011).

Page 69, 400,000 deaths: See The Health Consequences of Smoking: A Report of the Surgeon General (May 27, 2004) and also the Center for Disease Control publication Tobacco Use: Targeting the Nation’s Leading Killer, At A Glance 2011.

Page 69, global warming: See Spencer Weart’s terrific book and website on The Discovery of Global Warming, including the 1979 Charney Report. Quote 1 on this page is from J. Murray Mitchell, Jr. 1977 (“Carbon dioxide and future climate”, NOAA Electronic Data Service March 1977, pp3-10), who writes: “Suppose we elect to ignore the problem of carbon dioxide until it is staring us in the face—perhaps in another 20 years—in the form of a clear signal that a global warming trend has begun that is unmistakeably attributable to the further accumulation of carbon dioxide in the atmosphere.” Mitchell also writes: “It seems likely that industrial man already has started to have an impact on global climate.” And also: “The consequences [of CO2 / of burning fossil fuels] are likely to become noticeable by the end of this century…” And also: “Perhaps in another 20 years [there will be] a clear signal that a global warming trend has begun.” Quote 2 is from Wallace C. Broecker, “Climatic Change: Are We on the Brink of a Pronounced Global Warming?” Science 189: 460-463, 1975: “[B]y the first decade of the next century we may experience global temperatures warmer than any in the last 1000 years.” Note that AR5 WG1 Figure 5.7(c) (IPCC 2014) shows that recent temperatures are indeed warmer than in the past 1000 years.

The temperature increase of about 0.15C per decade can be seen in the NOAA data on which the graph is based. (Choose “Globe” and then “Annual”.) See also the decadal averages in AR5 WG1 Figure SPM.1, Table 2.7, and Figure 2.19 (IPCC 2014). The predictions of 0.2C per decade come from, e.g., AR4 WG1 SPM (IPCC 2007: “For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios”) but it is worth noting that AR5 WG1 SPM (IPCC 2014, page 20) takes a somewhat more nuanced view: “The global mean surface temperature change for the period 2016–2035 relative to 1986–2005 will likely be in the range of 0.3°C to 0.7°C (medium confidence).”

Page 70, fingerprints: Note that “fingerprinting” is a technical term; see here and here.

Page 71, vast majority of scientists: See collections of statements from Union of Concerned Scientists and from NASA. On the “not convinced” side, see for example the NIPCC (Nongovernmental International Panel on Climate Change).

Page 72, competing theories: See AR5 WG1 Technical Summary (IPCC 2014, page 73): “There is strong evidence that excludes solar forcing, volcanoes and internal variability as the strongest drivers of warming since 1950.” In addition, note that a good competing theory needs to attract significant support, and even in the “not convinced” community I haven’t seen significant support for any one “alternative” theory.

Page 73, evidence all around us: See organizations like the USA National Phenology Network and Nature’s Calendar in the UK. On the pied flycatcher, see here.

Page 74, models do a pretty good job: On ice ages, see AR4 WG1 FAQ 6.1 (IPCC 2007): “Model simulations of ice age climate…. yield realistic results only if the role of CO2 is accounted for.” On volcanoes, see AR5 WG1 TFE.3 (IPCC 2014, page 65): “[IPCC] AR4 and AR5, however, did include the effects from volcanoes and did simulate successfully the associated cooling.”

Chapter 7: Global warming (pages 77-88)

Page 79, “business as usual”: There are other definitions of “business as usual”, but this is the one that we’re using, roughly matching the IPCC’s RCP 8.5.

Page 80, “5 Chinas”: See UN World Population Prospects: The 2012 Revision, which estimates a 2010 world population of 6.9b, with 1.3b in the developed world, 1.4b in China, 1.2b in India, about 1.4b in other Asian countries, and about 1.6b for everyone else. Then see IEA, CO2 Emissions from Fuel Combustion: 2010 Edition, which estimates that in the year 2000 the 1.2b people in the OECD (essentially the rich world) had per-capita CO2 emissions of 12.6 tonnes (for a total of 12.6b tonnes) and that the 6.1b worldwide had per-capita emissions of 3.9 tonnes (for a total of 23.5b tonnes). PS. Another interesting reference here is the OECD’s “Looking to 2060: Long-term growth prospects for the world” (2012).

Page 81, “add another 2 Chinas”: See UN World Population Prospects: The 2012 Revision, which estimates a 2100 world population of 10.9b, which is 3.0b (or about 2 Chinas) more than the year 2010 world population of 6.9b.

Page 82, “emissions could rise 250%”: See the top of AR5 WG1 Figure TS.19 (IPCC 2014). The inset of that same figure shows the RCP 8.5 CO2 pathway rising towards 1000pppm in 2100.

Page 82, “CO2 concentrations haven’t been that high for millions of years”: See Kiehl 2011 (“Lessons from Earth’s Past”, ungated version may be here), which notes: “When was the last time the atmosphere contained ~1000 ppmv of CO2? Recent reconstructions of atmospheric CO2 concentrations through history indicate that it has been ~30 to 100 million years since this concentration existed in the atmosphere.”

Page 83, “about 4C”: See the bottom-left of AR5 WG1 Figure TS.15 or Figure SPM.7 (IPCC 2014).

Page 84, “the average summer in 2100”: See Battisti and Naylor, “Historical warnings of future food insecurity with unprecedented seasonal heat”, Science 323:240-244 (2009).

Page 86, oceans, land areas, Arctic: See AR5 WG1 Table 12.2 (IPCC 2014, page 1055).

Chapter 8: H2O (pages 89-100)

Page 90, water cycle: See USGS, “The Water Cycle”.

Page 90, water vapor: A climate scientist colleague notes: “if you can see it, it’s not water vapor – the visible “mist” is made of liquid water droplets. But the steam coming out of the teapot is water vapor!”

Page 92, “most of the extra energy…ends up in the oceans”: See AR5 WG1 Section TS.2.3 (IPCC 2014, page 39): “Ocean warming dominates that total heating rate [between 1971 and 2010], with full ocean depth warming accounting for about 93% (high confidence), and warming of the upper (0 to 700 m) ocean accounting for about 64%. Melting ice (including Arctic sea ice, ice sheets and glaciers) and warming of the continents each account for 3% of the total. Warming of the atmosphere makes up the remaining 1%.”

Page 92, “thermal expansion accounted for about half of the 7 inches of sea level rise”: See AR5 WG1 Table 13.1 (IPCC 2014, page 1151). See also AR5 WG1 SPM (IPCC 2014, page 11), which says: “Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.”

Page 93, “likely to accelerate”: See AR5 WG1 Figure SPM.9 (IPCC 2014).

Page 93, “2 feet of sea level rise”: See AR5 WG1 Table SPM.2 (IPCC 2014, page 23), noting that 2 feet is about 0.6m and that 4 feet is about 1.2m. See also AR5 WG1 Figure 13.27 (IPCC 2014).

Page 94, “Arctic Circle”: The quote comparing the Arctic to the Mediterranean is from Scott Borgerson, “The Coming Arctic Boom”, Foreign Affairs (July/Aug 2013).

Page 95, Winter Olympics: See The Future of the Winter Olympics in a Warmer World, described in the article “Climate change threatens Winter Olympics”. See also “The End of Snow?” by Powder magazine editor Porter Fox (NY Times, Feb 7 2014).

Page 95, snow: See AR5 WG1 SPM (IPCC 2014, page 9): “There is very high confidence that the extent of Northern Hemisphere snow cover has decreased since the mid-20th century (see Figure SPM.3).”

Page 96, “Clausius-Clapeyron”: See AR4 WG1 FAQ 3.2 (IPCC 2007). A climate scientist colleague notes: “A good example of Clausius-Clapeyron in action is the fact that summer is much more humid than winter everywhere (even in Seattle, where it never rains in summer and always rains in winter!).”

Page 97, precipitation: See AR5 WG1 TFE.9 (IPCC 2014, page 112): “Under the [RCP8.5 scenario], projections by the end of the century indicate an increased risk of drought is likely (medium confidence) in presently dry regions linked to regional to global-scale projected decreases in soil moisture.” See also AR5 WG1 FAQ 12.2 (IPCC 2014, page 1085): “These changes produce two seemingly contradictory effects: more intense downpours, leading to more floods, yet longer dry periods between rain events, leading to more drought.” See also AR5 WG1 Chapter (IPCC 2014, page 984): “The general pattern of wet-get-wetter… and dry-get-drier has been confirmed”.

Page 98-100, ocean acidification: See AR5 WG1 Chapter (IPCC 2014, page 136): “[O]cean acidification poses potentially serious threats to the health of the world ocean ecosystems (see AR5 WGII assessment).” And here’s a neat video (including a do-it-yourself experiment!) from the University of Washington Dept of Atmospheric Sciences; there’s also an Australian video on Hermie the hermit crab.

Page 99, “tiny sea creatures”: See also stories in the media such as Craig Welch, “Sea changes harming ocean now could someday undermine marine food chain”, Seattle Times, Nov 25 2012.

Chapter 9: Life on Earth (pages 101-110)

Page 103, “caused by humans”: Note that the original five boxes connect to the acronym HIPPO: Habitat Loss, Invasive Species, Pollution, Human Population, and Overharvesting.

Page 103, “40-70% of species”: See AR4 WG2 Section 4.4.11 (IPCC 2007): “As global average temperature exceeds 4°C above pre-industrial levels, model projections suggest significant extinctions (40-70% species assessed) around the globe”. YB: Look at draft of IPCC AR5 WG2 when it comes out March 29.

Chapter 10: Beyond 2100 (pages 111-120)

Page 113, “sea levels (and maybe also temperatures) would continue to rise”: See AR5 WG1 Chapter 13 (IPCC 2014, page 1140): “It is virtually certain that global mean sea level rise will continue beyond 2100, with sea level rise due to thermal expansion to continue for many centuries.” Whether or not temperatures continue to rise depends on climate sensitivity; see, e.g., the figures in Roe and Bauman 2013.

Page 114, “CO2 is a long-lived gas”: See AR5 WG1 FAQ 12.3 (IPCC 2014, page 1106): “For an emission pulse of about 1000 PgC, about half is removed within a few decades, but the remaining fraction stays in the atmosphere for much longer. About 15 to 40% of the CO2 pulse is still in the atmosphere after 1000 years.” See also AR5 WG1 Box 6.1, Figure 1 (IPCC 2014). Note that the left and middle panels refer to an instantaneous CO2 pulse of 100 PgC; from the bottom of AR5 WG1 Figure TS.19 (IPCC 2014) we see that fossil fuel emissions from the 1860s through 2005 have totaled about 300PgC. See also AR5 WG1 FAQ 6.2 (IPCC 2014, pages 544-545) and also Archer and Brovkin 2008 (“The millennial atmospheric lifetime of anthropogenic CO2”, Climatic Change): “The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20–60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste.” Archer is also the author of the book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate (2010).

Page 117, ice sheets: On the West Antarctic Ice Sheet, see AR5 WG1 Chapter (IPCC 2014, page 1172): “the West Antarctic ice sheet alone has the potential to raise sea level by [approximately] 4.3 m” [14 ft]. On the Greenland Ice Sheet, see page 1140: “The available evidence indicates that sustained global warming greater than a certain threshold above pre-industrial would lead to the near-complete loss of the Greenland ice sheet over a millennium or more, causing a global mean sea level rise of about 7 m [23 ft].” See also AR4 WG1 FAQ 10.2 (IPCC 2007), which says that “the total melting of the Greenland Ice Sheet, which would raise global sea level by about seven metres, is a slow process that would take many hundreds of years to complete” and that “the collapse of [the West Antarctic Ice Sheet] would trigger another five to six metres of sea level rise.”

Page 118, “The world population could be 2 billion… or 36 billion”: See the UN’s World Population in 2300 (2003), which has a best guess of world population in 2300 of 9 billion, with 2.3 billion as a low variant and 36.4 billion as a high variant.

Page 118, “imagine some in 1900 trying to anticipate today’s world”: This idea is based on a fabulous article (actually a 1992 American Economic Association presidential address) by a Nobel Prize-winning economist: Thomas C. Schelling, “Some economics of global warming”, American Economic Review 82:1-14, 1992.

Page 119, Arrhenius: See page 63 of his book Worlds in the Making: The Evolution of the Universe (1908): “We often hear lamentations that the coal stored up in the earth is wasted by the present generation without any thought of the future, and we are terrified by the awful destruction of life and property which has followed the volcanic eruptions of our days. We may find a kind of consolation in the consideration that here, as in every other case, there is good mixed with the evil. By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind.”

Page 119, it’s tough to make predictions, especially about the future: This quote and variants of it are attributed to everyone from Mark Twain to Neils Bohr to Samuel Goldwyn, e.g., see The Economist. More from Quote Investigator, which concludes that it’s probably Danish in origin.

Chapter 11: Uncertainty (pages 121-132)

Page 123, “these odds are less than 1 in 3”: For probability terminology, see AR5 WG1 Box TS.1 (IPCC 2014, page 36). Regarding Greenland ice sheet melt, see AR5 WG1 Table 12.4 (IPCC 2014, page 1115), which rates it as “Exceptionally unlikely that either Greenland or West Antarctic Ice sheets will suffer near-complete disintegration (high confidence).” Regarding the lottery, the odds of winning Powerball are apparently about 1 in 175 million.

Page 124, “scientific predictions”: On temperatures, see AR5 WG1 Figure 1.4 (IPCC 2014); on sea level rise, see AR5 WG1 Figure 1.10 (IPCC 2014); on methane, see AR5 WG1 Figure 1.6 (IPCC 2014); on Arctic ice, see the graphic in this Arctic Sea Ice Blog post and also AR5 WG1 Section (IPCC 2014, page 137), which says “Sea ice extent has been diminishing significantly faster than projected by most of the AR4 climate models” and Section 4.8 (page 368), which says: “Some of the observed changes since AR4 have been considerable and unexpected. One of the most visible was the dramatic decline in the September minimum sea ice cover in the Arctic in 2007, which was followed by a record low value in 2012.”

Page 126, “don’t put the microphone in front of the speaker”: This is a reference to Roe and Baker 2007 (“Why Is Climate Sensitivity So Unpredictable?” Science); they argue that feedbacks make it harder to rule out high climate sensitivities than low climate sensitivities.

Page 126, “negative feedback loop”: See AR5 WG1 Section 1.2.2 (IPCC 2014, page 127): “The dominant negative feedback is the increased emission of energy through LWR [longwave radiation] as surface temperature increases (sometimes also referred to as blackbody radiation feedback).”

Page 129, “if reality turns out to be worse than we’d thought”: See for example AR5 WG1 FAQ 6.1 (IPCC 2014, pages 530-531): “Could Rapid Release of Methane and Carbon Dioxide from Thawing Permafrost or Ocean Warming Substantially Increase Warming?”

Page 132, insurance: The “insurance” metaphor/argument is found repeatedly in economics discussions of climate change, e.g., Marty Weitzman: “The basic issue here is that spending money to slow global warming should perhaps not be conceptualized primarily as being about consumption smoothing as much as being about how much insurance to buy to offset the small change of a ruinous catastrophe that is difficult to compensate by ordinary savings (Martin L Weitzman, “A Review of The Stern Review on the Economics of Climate Change, Journal of Economic Literature 45:703-724, 2007).

Chapter 12: The Tragedy of the Commons (pages 135-144)

Page 137, costs and benefits: See for example Cass Sunstein, “Climate Change: Lessons From Ronald Reagan” (NY Times, Nov 10 2012): “Economists of diverse viewpoints concur that if the international community entered into a sensible agreement to reduce greenhouse gas emissions, the economic benefits would greatly outweigh the costs.” One prominent cost-benefit model is the Yale economist Bill Nordhaus’s DICE model; see here. A related concept is the “social cost of carbon”, which estimates the optimal carbon tax for dealing with climate change; see this EPA analysis.

Page 138, tragedy of the commons: “The tragedy of the commons” (easier to read in PDF) refers to a 1968 article in Science by Garrett Hardin. For more on this see our Cartoon Econ books, especially Volume One: Microeconomics.

Page 139, Aristotle: See Aristotle’s Politics (written 350 B.C.E., translated by Benjamin Jowett), Book Two, Part III: “For that which is common to the greatest number has the least care bestowed upon it. Every one thinks chiefly of his own, hardly at all of the common interest; and only when he is himself concerned as an individual.”

Page 141, entire countries: The reference here is to efforts like the Kyoto Protocol, an attempted global CO2 treaty from the 1990s. As noted by Wikipedia, “The U.S. signed the Protocol, but did not ratify it [and] the U.S. Senate passed the Byrd-Hagel Resolution unanimously disapproving of any international agreement that 1) did not require developing countries to make emission reductions and 2) “would seriously harm the economy of the United States”. In addition, Wikipedia notes that “In 2011, Canada, Japan and Russia stated that they would not take on further Kyoto targets. The Canadian government announced its withdrawal [from] the Kyoto Protocol on 12 December 2011… Canada was committed to cutting its greenhouse emissions to 6% below 1990 levels by 2012, but in 2009 emissions were 17% higher than in 1990.” Finally, it’s worth noting that developing countries like China and India had no binding emissions targets under the Kyoto Protocol.

Page 142, “self-interest is not all bad”: Adam Smith was a Scottish philosopher and “the father of modern economics”. The quote about the butcher, the brewer, and the baker comes from The Wealth of Nations, first published in 1776. (You can still buy it today, and though not always a page-turner it’s remarkably readable.)

Page 142, “sometimes self-interest happens to coincide with emissions reductions”: These are called “co-benefits”, many of them dealing with the health benefits of reduced (local) air pollution that can accompany reductions of (global) CO2 emissions. See for example here, here, and here.

Page 143, “history shows that”: See for example “The Montreal Protocol, a Little Treaty That Could” (NY Times, Dec 9 2013).

Page 144, border tax adjustments: There are plenty of questions about BTAs, both legal questions (e.g., about whether BTAs would violate international trade rules) and economic/policy questions (e.g., how would you actually try to calculate the carbon content embedded in a computer made in Taiwan?). For one perspective here see the Carbon Tax Center.

Chapter 13: Techo-Fix (pages 145-158)

Page 146, geoengineering: See for example the Oxford Geoengineering Program. An early-ish article about this was “How Earth-Scale Engineering Can Save the Planet” (Popular Science, June 22 2005). PS. Richard Gammon notes that this should really say “upper atmosphere”.

Page 146, “genetically modified carbon-eating trees”: The reference is to an article about physicist Freeman Dyson (“The Civil Heretic”, NY Times, Mar 25 2009):

Then he added the caveat that if CO2 levels soared too high, they could be soothed by the mass cultivation of specially bred “carbon-eating trees,” whereupon the University of Chicago law professor Eric Posner looked through the thick grove of honorary degrees Dyson has been awarded — there are 21 from universities like Georgetown, Princeton and Oxford — and suggested that “perhaps trees can also be designed so that they can give directions to lost hikers.”

Page 147, “the single best objection to the garden hose idea”: The quote is from Super Freakonomics, a 2009 book by University of Chicago economist Steven Levitt and journalism Stephen Dubner. The chapter on climate change in the book prompted a strong response from climate scientists, including Levitt’s U of C colleague Ray Pierrehumbert’s quite amusing blog post “An open letter to Steve Levitt”. My own thoughts on the book, and my email exchange with Levitt, is on my blog: Part 1, Part 2, Part 3.

Page 151, “negawatts”: The term “negawatts” was coined by Amory Lovins of the Rocky Mountain Institute.

Page 153, subsidies: The International Energy Agency says that “fossil-fuel consumption subsidies worldwide amounted to $409 billion in 2010”.

Page 158, controversy: See for example Roger Pielke Jr’s “Iron Law” of Climate Policy.

Chapter 14: Putting a Price on Carbon (pages 159-170)

This material can all be found in any introductory environmental economics textbook, and a good bit of it is in our Cartoon Econ books.

Page 162, B.C. carbon tax: More from my 2012 NY Times op-ed (“The Most Sensible Tax of All”, co-authored with Shi-Ling Hsu), Sustainable Prosperity’s 2013 report on BC’s Carbon Tax Shift After Five Years, and lots from Sightline Institute’s blog, e.g., this.

Page 166, fisheries: Cap and trade systems for fisheries are usually called catch share systems or IFQ or ITQ systems (“individual fishing quota” or “individual transferable quoata”). The USA has a number of such policies; for details see NOAA. Note that such policies often feature multi-year permits, e.g., if you have a 1% catch share and the Total Allowable Catch is 100,000 tons this year and 150,000 tons next year then you get to catch 1,000 tons this year and 1,500 tons next year.

Page 170, “a necessary and sufficient step”: The quote is from Yale economist William Nordhaus, who writes “To a first approximation, raising the price of carbon is a necessary and sufficient step for tackling global warming. The rest is at best rhetoric and may actually be harmful in inducing economic inefficiencies” (A Question of Balance: Weighing the Options on Global Warming Policies, 2008, full text available here).

Chapter 15: Beyond Fossil Fuels (pages 171-182)

Page 172, CH4 and SF6: See AR5 WG1 Table 8.A.1 (IPCC 2014, page 731-733), which shows that methane (CH4) has a 100-year GWP of 28 and SF6 has a 100-year GWP of 23,500. Note that CO2 is the benchmark used to discuss the Global Warming Potential (GWP) of other greenhouse gases. (The GWP of CO2 is always defined to be 1, with other gases measured in terms of their CO2 equivalents.) The topic is a bit tricky because all of these gases have varying atmospheric lifetimes, and as a result GWPs are defined for a given time frame, e.g., over 20 years methane (CH4) has a GWP of 84 (meaning that over 20 years a molecule of methane generates as much warming as 84 molecules of CO2) but over 100 years methane has a GWP of only 28; that’s because CO2 is a long-lived gas and methane is not.

Page 175, rich countries, poor countries: See FAO’s Global Forest Resources Assessment 2010, which says that “around 13 million hectares of forests were converted to other uses or lost through natural causes each year in the last decade” but that the net change in forest area is only -5.2m hectares per year. They also say China is afforesting rapidly. On Norway and Indonesia, see here and here.

Page 178, black carbon: Richard Gammon notes that “two years and I’m outta here” should really be more like “two weeks and I’m outta here” (unless it’s in the upper atmosphere).

Page 180, “offsets are also used in many cap and trade systems”: For a skeptical view of this practice, see Annie Leonard’s video “The Story of Cap & Trade” (2009).

Chapter 16: The Challenge (pages 183-196)

Page 187, “without proper maintenance”: See this Cornell University page on Compost Physics: “Compost managers strive to keep the compost below about 65°C because hotter temperatures cause the beneficial microbes to die off.”

Page 190, “our task is daunting”: This is a version of the IPAT equation; see also the related Kaya Identity.

Page 191, “remember that CO2 stays in the atmosphere for a long, long time”: See page 114 and the associated notes and references there; a climate scientist colleague notes that we would have to cut emissions by 80-90% or so to get CO2 concentrations to stop rising.

Page 193, “it’s okay if your dream is different”: An “all-out mobilization” is a reference to the ideas of Joseph Romm of; see his 2006 book Hell and High Water: Global Warming–the Solution and the Politics–and What We Should Do, excerpted here. The “breakthrough” panel references the ideas of the Breakthrough Institute.

Page 195, “join a chorus”: More here on the Energy & Enterprise Initiative, which aims to “put the works on climate change from a right-of-center market-friendly angle focused on revenue-neutral carbon taxes; on the Sierra Club; and on Citizens Climate Lobby, a grassroots group working for federal “fee and dividend” legislation.

Glossary (pages 197-205)

Air: See the entry in the AR5 WGI Glossary (IPCC 2014) for “atmosphere” for contents of atmosphere. Note that the percentages are for dry air, but water vapor only averages 1% of the total.

Albedo: See the entry in the AR5 WGI Glossary (IPCC 2014) for “energy budget” for Earth’s 30% albedo.

Ice ages: See the entry in the AR5 WGI Glossary (IPCC 2014) for “Last Glacial Maximum”, which peaked 21,000 years ago.

Interglacial period: See the entry in the AR5 WGI Glossary (IPCC 2014) for “Holocene”, the current interglacial period that started 12,000 years ago.

Temperature: See the entry in the AR5 WGI Glossary (IPCC 2014) for “energy budget” for current global average temperature of 15 °C.

Theory: Richard Gammons suggests we “add ‘theory’ and ‘hypothesis’ to the Glossary, making clear that a scientific ‘theory’ like ‘gravity’ or ‘relativity’ or ‘quantum’ is considered well established, and has withstood years of criticism and observational evidence, so much more than ‘just a theory’!”