Unsettled Quotes

“The assessment reports downplay this embarrassment of unphysical average temperatures by focusing on the rise in the average temperature and displaying the temperature changes calculated by each model, rather than the temperatures themselves. This makes differences among the ensemble members less apparent;”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The average of results over many different models suggests that the net effect of all feedbacks is to double or triple CO2’s direct warming influence.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Upward flows of energy and water vapor (think thunderhead clouds) occur over areas much smaller than the 100 km (60 miles) of our grid. This is particularly troublesome in the tropics, where upward flows are important in lofting energy and water vapor from the ocean surface into the atmosphere. In fact, the flow of energy carried into the atmosphere by evaporation of the ocean waters is more than thirty times larger than the human influences shown back in Figure 2.4. So subgrid assumptions about this “moist convection”—how air and water vapor move vertically through the flat grid boxes—are crucial to building accurate models.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“if the grid is finer, the time step has to be smaller as well, meaning even more computer time will be required. As an illustration, a simulation that takes two months to run with 100 km grid squares would take more than a century if it instead used 10 km squares. The run time would remain at two months if we had a supercomputer one thousand times faster than today’s—a capability probably two or three decades in the future.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“instead of making precise predictions of future concentrations, the IPCC created a set of scenarios. They have the rather complicated name of “Representative Concentration Pathways,” or RCPs. These are meant to span a plausible range of possibilities for population, economy, technology, and so on.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“One additional point about methane that surprises many people is that fossil fuels account for only about one quarter of global human-caused methane emissions, as shown in Figure 3.5. Rather, most methane emissions arise from enteric fermentation (digestion in cattle—mostly emitted from the front of the animal, not the back) and other agricultural activities, particularly rice cultivation; the decay of material in landfills is also significant. So any effort to drastically reduce emissions must also address those sources.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“But there are several important differences between methane and carbon dioxide. One is that methane concentrations are much lower (2,000 parts per billion, which is about 1/200th that of CO2’s 400 parts per million). Another difference is that a methane molecule lasts in the atmosphere for only about twelve years—though after that, chemical reactions covert it to CO2. And a third difference is that, because of the peculiarities of how molecules interact with the different colors of infrared radiation, every additional methane molecule in the atmosphere is thirty times more potent in warming than a molecule of carbon dioxide. These differences—lower concentration and shorter lifetime, but greater warming potency—must be taken into account when comparing CH4 and CO2 emissions. For instance, the 300 million tons of methane humans emit each year is only 0.8 percent of the 36 gigatons of CO2 emitted by burning fossil fuels.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Methane, the second most important human-caused greenhouse gas, has also been increasing over the past century and so also exerts a growing warming influence on the climate.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Carbon dioxide is the single human-caused greenhouse gas with the largest influence on the climate. But it is of greatest concern also because it persists in the atmosphere/surface cycle for a very long time. About 60 percent of any CO2 emitted today will remain in the atmosphere twenty years from now, between 30 and 55 percent will still be there after a century, and between 15 and 30 percent will remain after one thousand years.7 The simple fact that carbon dioxide lasts a long time in the atmosphere is a fundamental impediment to reducing human influences on the climate. Any emission adds to the concentration, which keeps increasing as long as emissions continue. In other words, CO2 is not like smog, which disappears a few days after you stop emissions; it takes centuries for the excess carbon dioxide to vanish from the atmosphere. So modest reductions in CO2 emissions would only slow the increase in concentration but not prevent it. Just to stabilize the CO2 concentration, and hence its warming influence, global emissions would have to vanish.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Carbon dioxide is the single human-caused greenhouse gas with the largest influence on the climate. But it is of greatest concern also because it persists in the atmosphere/surface cycle for a very long time. About 60 percent of any CO2 emitted today will remain in the atmosphere twenty years from now, between 30 and 55 percent will still be there after a century, and between 15 and 30 percent will remain after one thousand years.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“However, if the trends of the past decade continue, it will be some 250 years before the concentration reaches 1,000 ppm, which would be at 3.3 on this chart.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Only once in the geological past—the Permian period, 300 million years ago—have atmospheric CO2 levels been as low as they are today. Plant and animal life flourished abundantly during times when CO2 levels were five or ten times higher than today’s. But those were different plants and animals. So while carbon dioxide, in and of itself, is not particularly a concern for the planet, what is a concern is that, because life today has evolved to be well-suited to a low level of CO2 (anatomically modern humans appeared only some 200,000 years ago, at the extreme right of this chart), the rapid increases of the past century might prove disruptive. Concentrations up to 1,000 ppm (2.5 times that in open air today) are common in classrooms or auditoriums.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“zooming out to look over geological times gives us a quite different perspective. The natural processes moving the earth’s carbon around were different in the past, so much so that by geological standards, today’s Earth is starved for atmospheric CO2”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“A fourth, more subtle confirmation comes from carbon isotopes—the relatively rare carbon atoms that are about 8 percent heavier than ordinary carbon atoms. About 1.1 percent of the earth’s carbon is the isotope 13C; the rest is the lighter isotope 12C. But the proportion of 12C and 13C isn’t the same in all forms of carbon. In particular, the chemical reactions of life have a very slight preference for 12C, so that the carbon in living things (as opposed to mineral carbon in the earth’s crust) is “light”; that is, it has a slightly lesser proportion of 13C. Since the carbon in the atmosphere’s CO2 has become progressively “lighter” over the decades, we can infer that it arises from the burning of fossil fuels, which, after all, were once living things.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The CO2 emitted by burning fossil fuels disrupts the balance of this great annual cycle, since that carbon has been pulled out of the deep underground, where it was isolated from these natural processes. The amount of carbon that fossil fuel use adds to the cycle is currently about 4.5 percent of what flows each year. About half of that increase is taken up annually by the surface (the rising CO2 has increased vegetation over much of the planet), and the remainder stays in the atmosphere, increasing its CO2 concentration.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The earth formed 4.5 billion years ago with a fixed endowment of carbon. Today, that carbon is found in several different circumstances around the planet—what are called “reservoirs.” The largest reservoir by far is the earth’s crust, which contains almost all of the planet’s carbon, about 1.9 billion gigatons (1 gigaton, abbreviated Gt, is one billion tons).2 The next largest amount, about 40,000 Gt, is in the oceans, almost all of that far below the surface. There are about 2,100 Gt more stored on land in soils and living things, and 5,000–10,000 Gt in fossil fuels underground. The roughly 850 Gt of carbon in the atmosphere, almost all in the form of carbon dioxide, is equal to about 25 percent of the carbon at or near the earth’s surface (in the soils, plants, and shallow ocean) but is only 2 percent of the total carbon in the oceans.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The most significant human-caused greenhouse gases influencing the climate are carbon dioxide (CO2) and methane (CH4). Their concentrations in the atmosphere are increasing because we’re emitting them; that’s why efforts to reduce human influences on the climate focus on reducing emissions.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“By far the largest human influence on the climate system, and the one nearly all climate policy has focused upon, is the emission of greenhouse gases.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“That human heat can indeed affect the local climate where this energy use is concentrated (for example in cities and near power plants). But averaged over the globe, it currently amounts to only 0.03 W/m2, some ten thousand times smaller than the natural heat flows of the climate system, and about one hundred times smaller than the other human influences”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Another source of heat input into the climate system is the energy that humans derive from fossil fuels and nuclear material. After that energy is used for heating, mobility, and generating electricity, the Second Law of Thermodynamics guarantees that virtually all of it ends up as heat in the climate system, ultimately to be radiated into space along with the earth’s natural heat emissions.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The sunlight energy absorbed by the earth (and hence the heat energy radiated by the earth) amounts to an average of 239 W/m2. Since a 100-watt incandescent light bulb gives off, well, one hundred watts (almost all as heat), this means the planet radiates heat as if there were a bit more than two light bulbs in every square meter (eleven square feet) of its surface. Human influences today amount to just over 2 W/m2, or slightly less than 1 percent of that natural flow (about the same influence as half a cucumber on the daily human diet).”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Not all human influences are warming. Aerosols are fine particles in the atmosphere such as those produced by the burning of low-quality coal. They cause severe health problems, contributing to millions of deaths per year. But they also make the globe more reflective both by directly reflecting sunlight and by inducing the formation of reflective clouds. Human-caused aerosols, together with changes in land use like deforestation (pasture is more reflective than forest), increase the albedo and so exert a net cooling influence that cancels about half of the warming influence of human-caused greenhouse gases.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Understanding how the climate system responds to human influences is, unfortunately, a lot like trying to understand the connection between human nutrition and weight loss, a subject famously unsettled to this day. Imagine an experiment where we fed someone an extra half cucumber each day. That would be about an extra twenty calories, a 1 percent increase to the average 2,000-calorie daily adult diet. We’d let that go on for a year and see how much weight they gained. Of course, we would need to know many other things to draw any meaningful conclusions from the results: What else did they eat? How much did they exercise? Were there any changes in health or hormones that affect the rate at which they burn calories? Many things would have to be measured precisely to understand the effect of the additional cucumbers, although we would expect that, all else being equal, the added calories would add some weight. The problem with human-caused carbon dioxide and the climate is that, as in the cucumber experiment, all else isn’t necessarily equal, as there are other influences (forcings) on the climate, both human and natural, that can confuse the picture. Among the other human influences on the climate are methane emissions into the atmosphere (from fossil fuels, but more importantly from agriculture) and other minor gases that together exert a warming influence almost as great as that of human-caused CO2.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“There are two takeaways from this graph. One is the complexity of the spectra—hundreds of thousands of molecular properties, many measured in the laboratory, go into creating these simulated spectra, which agree very well with satellite observations. Second, although the effect of CO2 at today’s concentration is significant (7.6 percent), doubling it doesn’t change things much (an additional 0.8 percent) due to the “painting a black window” effect we’ve already discussed.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“While we’ve talked about how the overall amount of that radiation has to balance the warming sunlight, the radiation is actually spread over a spectrum of different wavelengths. Think of those like “colors,” although not visible to our eyes. Water vapor, the most significant greenhouse gas, intercepts only some colors, but because it blocks almost 100 percent of those it does, adding more water vapor to the atmosphere won’t make the insulation much thicker—it would be like putting another layer of black paint on an already black window. But that’s not true for carbon dioxide. That molecule intercepts some colors that water vapor misses, meaning a few molecules of CO2 can have a much bigger effect (like the first layer of black paint on a clear window). So the greater potency of a CO2 molecule depends upon relatively obscure aspects of how it, and water vapor, intercept heat radiation—another example of why the details are important when attempting to understand human influences on the climate.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“how could changing fewer than three molecules out of 10,000, a 0.03 percent change, increase the atmosphere’s heat-intercepting ability by about thirty times that amount (1 percent)? And”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The next most significant greenhouse gas, carbon dioxide (CO2), is different from water vapor in that its concentration in the atmosphere is much the same all over the globe. CO2 currently accounts for about 7 percent of the atmosphere’s ability to intercept heat. It’s also different in that human activities have affected its concentration (that is, the fraction of air molecules that are CO2). Since 1750, the concentration has increased from 0.000280 (280 parts per million or ppm) to 0.000410 (410 ppm) in 2019, and it continues to go up 2.3 ppm every year. Although most of today’s CO2 is natural, there is no doubt that this rise is, and has been, due to human activities, primarily the burning of fossil fuels.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“Water vapor is the most important of the greenhouse gases. Of course, the amount in the atmosphere at any given place and time varies greatly (the humidity changes a lot with the weather). But on average, water vapor amounts to only about 0.4 percent of the molecules in the atmosphere. Even so, it accounts for more than 90 percent of the atmosphere’s ability to intercept heat.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“The most common of the gases making up the earth’s atmosphere are nitrogen (78 percent) and oxygen (21 percent). Combined, then, these two account for 99 percent of the dry atmosphere, and because of the peculiarities of molecular structure, heat passes through them easily. The largest part of the remaining 1 percent is the inert gas argon. But while even less abundant, some of the other gases—most significantly water vapor, carbon dioxide, methane, nitrous oxide, and ozone—intercept, on average, about 83 percent of the heat emitted by the earth’s surface.8 So the earth does indeed emit energy equivalent to what it absorbs from the sun, but instead of directly flowing off into space, cooling our planet to a chilly average of 0ºF, much of that energy is intercepted by the atmosphere blanketing us.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters

“It’s often said that greenhouse gases “trap” heat, which gives the impression that the heat never escapes. But all of the heat must eventually be radiated to space to keep the planet in energy balance, as discussed earlier. The radiated heat must balance the absorbed solar energy very precisely, to within less than one-half a percent. If it didn’t, we’d see the earth warming or cooling much more rapidly than we do. So when discussing the effect of greenhouse gases on the heat flowing from the earth’s surface, a more appropriate metaphor is “catch and release.” For this reason, I’ll use the terms “intercept” and “impede” rather than “trap.”
― Steven E. Koonin, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters