This is an update to a previous post on the climate science brief submitted to Judge Alsup’s tutorial.  In a recent article, Dr. Fred Singer draws some implications from one of the many points in the brief written by Happer, Koonin and Lindzen.  The Singer essay is Does the Greenhouse Gas CO2 cool the climate? in the American Thinker.

First the pertinent paragraph from the legal brief.  In responding to Judge Alsup’s eighth question the scientists said this (my bolds):

On average, the absorption rate of solar radiation by the Earth’s surface and atmosphere is equal to emission rate of thermal infrared radiation to space. Much of the radiation to space does not come from the surface but from greenhouse gases and clouds in the lower atmosphere, where the temperature is usually colder than the surface temperature, as shown in the figure on the previous page. The thermal radiation originates from an “escape altitude” where there is so little absorption from the overlying atmosphere that most (say half) of the radiation can escape to space with no further absorption or scattering. Adding greenhouse gases can warm the Earth’s surface by increasing the escape altitude. To maintain the same cooling rate to space, the temperature of the entire troposphere, and the surface, would have to increase to make the effective temperature at the new escape altitude the same as at the original escape altitude. For greenhouse warming to occur, a temperature profile that cools with increasing altitude is required.

Over most of the CO2 absorption band (between about 580 cm-1 and 750 cm-1 ) the escape altitude is the nearly isothermal lower stratosphere shown in the first figure. The narrow spike of radiation at about 667 cm-1 in the center of the CO2 band escapes from an altitude of around 40 km (upper stratosphere), where it is considerably warmer than the lower stratosphere due heating by solar ultraviolet light which is absorbed by ozone, O3. Only at the edges of the CO2 band (near 580 cm-1 and 750 cm-1 ) is the escape altitude in the troposphere where it could have some effect on the surface temperature. Water vapor, H2O, has emission altitudes in the troposphere over most of its absorption bands. This is mainly because water vapor, unlike CO2, is not well mixed but mostly confined to the troposphere.

Dr. Singer picks up on this and comments (my bolds):

“Greenhouse gas” only means that CO2 absorbs some infrared (IR) radiation; it does not guarantee climate warming.

In fact, the outcome depends mostly on atmospheric structure, measured by balloon-borne radiosondes. It is expressed by the so-called atmospheric lapse rate (ALR), defined as change in atmospheric temperature with altitude.[ii] [Note that “lapse rate” has nothing to do with back-sliding alcoholics and smokers.]

Physicists who have examined our counter-intuitive hypothesis, all agree with the science — albeit somewhat reluctantly. Such is the power of group-think that even experts, with some exception, find the idea that CO2 might cool the climate difficult to accept.

STRATOSPHERE	ALR is positive	Temperature increases with altitude
TROPOPAUSE	ALR is zero	Temperature is constant
TROPOSPHERE	ALR is negative	Temperature decreases with altitude

The ALR is generally negative in the troposphere[iii] as much as [minus] -6.5 degree C per km of altitude. [The troposphere is the lowest atmospheric layer, from zero up to about 50,000 foot altitude.]

ALR goes through zero in the tropopause region, the layer that separates the troposphere from the overlying stratosphere. The ALR turns positive in the stratosphere, just above [see schematic nearby.[iv] [The warming of the stratosphere is produced by absorption of energy by stratospheric ozone.]

The key result

Adding a tiny increment of CO2 raises slightly the “effective” altitude for emitting Outgoing Long-wave (OLR), the Radiation (IR), going out to space from a CO2 molecule.

Because of the reversal in the atmospheric temperature structure, OLR is:

1. of lower energy than normal if the effective altitude remains in the troposphere; and

2. a bit higher than normal if this effective altitude is in the stratosphere.

In case 2., the stratospheric CO2 emission “borrows” some energy from the surface emission — hence “cooling” the surface.

The previous post Cal Climate Tutorial: The Meat appears below as background.

An overview of a submission by Professors Happer, Koonin and Lindzen was in Climate Tutorial for Judge Alsup

This post goes into the meat and potatoes of that submission with excerpts from Section II: Answers to specific questions (my bolds)

Question 1: What caused the various ice ages (including the “little ice age” and prolonged cool periods) and what caused the ice to melt? When they melted, by how much did sea level rise?

The discussion of the major ice ages of the past 700 thousand years is distinct from the discussion of the “little ice age.” The former refers to the growth of massive ice sheets (a mile or two thick) where periods of immense ice growth occurred, lasting approximately eighty thousand years, followed by warm interglacials lasting on the order of twenty thousand years. By contrast, the “little ice age” was a relatively brief period (about four hundred years) of relatively cool temperatures accompanied by the growth of alpine glaciers over much of the earth.

The last glacial episode ended somewhat irregularly. Ice coverage reached its maximum extent about eighteen thousand years ago. Melting occurred between about twenty thousand years ago and thirteen thousand years ago, and then there was a strong cooling (Younger Dryas) which ended about 11,700 years ago. Between twenty thousand years ago and six thousand years ago, there was a dramatic increase in sea level of about 120 meters followed by more gradual increase over the following several thousand years. Since the end of the “little ice age,” there has been steady increase in sea-level of about 6 inches per century.

As to the cause of the “little ice age,” this is still a matter of uncertainty. There was a long hiatus in solar activity that may have played a role, but on these relatively short time scales one can’t exclude natural internal variability. It must be emphasized that the surface of the earth is never in equilibrium with net incident solar radiation because the oceans are always carrying heat to and from the surface, and the motion systems responsible have time scales ranging from years (for example ENSO) to millennia.

The claim that orbital variability requires a boost from CO2 to drive ice ages comes from the implausible notion that what matters is the orbital variations in the global average insolation (which are, in fact, quite small) rather than the large forcing represented by the Milankovitch parameter. This situation is very different than in the recent and more modest shorter-term warming, where natural variability makes the role of CO2 much more difficult to determine.

Question 2: What is the molecular difference by which CO2 absorbs infrared radiation but oxygen and nitrogen do not?

Molecules like CO2, H2O, CO or NO are called a greenhouse-gas molecules, because they can efficiently absorb or emit infrared radiation, but they are nearly transparent to sunlight. Molecules like O2 and N2 are also nearly transparent to sunlight, but since they do not absorb or emit thermal infrared radiation very well, they are not greenhouse gases. The most important greenhouse gas, by far, is water vapor. Water molecules, H2O, are permanently bent and have large electric dipole moments.

 

Question 3: What is mechanism by which infrared radiation trapped by CO2 in the atmosphere is turned into heat and finds its way back to sea level?

Unscattered infrared radiation is very good at transmitting energy because it moves at the speed of light. But the energy per unit volume stored by the thermal radiation in the Earth’s atmosphere is completely negligible compared to the internal energy of the air molecules.

Although CO2 molecules radiate very slowly, there are so many CO2 molecules that they produce lots of radiation, and some of this radiation reaches sea level. The figure following shows downwelling radiation measured at the island of Nauru in the Tropical Western Pacific Ocean, and at colder Point Barrow, Alaska, on the shore of the Arctic Ocean.

So the answer to the last part of the question, “What is the mechanism by which … heat … finds its way back to sea level?” is that the heat is radiated to the ground by molecules at various altitudes, where there is usually a range of different temperatures. The emission altitude is the height from which radiation could reach the surface without much absorption, say 50% absorption. For strongly absorbed frequencies, the radiation reaching the ground comes from low-altitude molecules, only a few meters above ground level for the 667 cm-1 frequency at the center of the CO2 band. More weakly absorbed frequencies are radiated from higher altitudes where the temperature is usually colder than that of the surface. But occasionally, as the data from Point Barrow show, higher-altitude air can be warmer than the surface.

Closely related to Question 3 is how heat from the absorption of sunlight by the surface gets back to space to avoid a steadily increasing surface temperature. As one might surmise from the figure, at Narau there is so much absorption from CO2 and by water vapor, H2O, that most daytime heat transfer near the surface is by convection, not by radiation. Especially important is moist convection, where the water vapor in rising moist air releases its latent heat to form clouds. The clouds have a major effect on radiative heat transfer. Cooled, drier, subsiding air completes the convection circuit. Minor changes of convection and cloudiness can have a bigger effect on the surface temperature than large changes in CO2 concentrations.

Question 4: Does CO2 in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?

The short answer to this question is “No”, but it raises some interesting issues that we discuss below.

Molecules can either scatter or absorb radiation. CO2 molecules are good absorbers of thermal infrared radiation, but they scatter almost none. Infrared radiant energy absorbed by a CO2 molecule is converted to internal vibrational and rotational energy. This internal energy is quickly lost in collisions with the N2 and O2 molecules that make up most of the atmosphere. The collision rates, billions per second, are much too fast to allow the CO2 molecules to reradiate the absorbed energy, which takes about a second. CO2 molecules in the atmosphere do emit thermal infrared radiation continuously, but the energy is almost always provided by collisions with N2 and O2 molecules, not by previously absorbed radiation. The molecules “glow in the dark” with thermal infrared radiation.

The figure shows that water vapor is by far the most important absorber. It can absorb both thermal infrared radiation from the Earth and shorter-wave radiation from the Sun. Water vapor and its condensates, clouds of liquid or solid water (ice), dominate radiative heat transfer in the Earth’s atmosphere; CO2 is of secondary importance.

If Question 4 were “Do clouds in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?” the answer would be “Yes”. It is common knowledge that low clouds on a sunny day shade and cool the surface of the Earth by scattering the sunlight back to space before it can be absorbed and converted to heat at the surface.

The figure shows that very little thermal radiation from the surface can reach the top of the atmosphere without absorption, even if there are no clouds. But some of the surface radiation is replaced by molecular radiation emitted by greenhouse molecules or cloud tops at sufficiently high altitudes that the there are no longer enough higher-altitude greenhouse molecules or clouds to appreciably attenuate the radiation before it escapes to space. Since the replacement radiation comes from colder, higher altitudes, it is less intense and does not reject as much heat to space as the warmer surface could have without greenhousegas absorption.

As implied by the figure, sunlight contains some thermal infrared energy that can be absorbed by CO2. But only about 5% of sunlight has wavelengths longer than 3 micrometers where the strongest absorption bands of CO2 are located. The Sun is so hot, that most of its radiation is at visible and near-visible wavelengths, where CO2 has no absorption bands.

Question 5: Apart from CO2, what happens to the collective heat from tail pipe exhausts, engine radiators, and all other heat from combustion of fossil fuels? How, if at all, does this collective heat contribute to warming of the atmosphere?

After that energy is used for heat, mobility, and 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 IR emissions. [A very small fraction winds up as visible light that escapes directly to space through the transparent atmosphere, but even that ultimately winds up as heat somewhere “out there.”]

 

 

How much does this anthropogenic heat affect the climate? There are local effects where energy use is concentrated, for example in cities and near power plants. But globally, the effects are very small. To see that, convert the global annual energy consumption of 13.3 Gtoe (Gigatons of oil equivalent) to 5.6 × 1020 joules. Dividing that by the 3.2 × 107 seconds in a year gives a global power consumption of 1.75 × 1013 Watts. Spreading that over the earth’s surface area of 5.1 × 1014 m2 results in an anthropogenic heat flux of 0.03 W/m2 . This is some four orders of magnitude smaller than the natural heat fluxes of the climate system, and some two orders of magnitude smaller than the anthropogenic radiative forcing.

Question 6: In grade school many of us were taught that humans exhale CO2 but plants absorb CO2 and return oxygen to the air (keeping the carbon fiber). Is this still valid? If so why hasn’t plant life turned the higher levels of CO2 back into oxygen? Given the increase in population on earth (four billion), is human respiration a contributing factor to the buildup of CO2?

If all of the CO2 produced by current combustion of fossil fuels remained in the atmosphere, the level would increase by about 4 ppm per year, substantially more than the observed rate of around 2.5 ppm per year, as seen in the figure above. Some of the anthropogenic CO2 emissions are being sequestered on land or in the oceans.

There is evidence that primary photosynthetic productivity has increased somewhat over the past half century, perhaps due to more CO2 in the atmosphere. For example, the summerwinter swings like those in the figure above are increasing in amplitude. Other evidence for modestly increasing primary productivity includes the pronounced “greening” of the Earth that has been observe by satellites. An example is the map above, which shows a general increase in vegetation cover over the past three decades.

The primary productivity estimate mentioned above would also correspond to an increase of the oxygen fraction of the air by 50 ppm, but since the oxygen fraction of the air is very high (209,500 ppm), the relative increase would be small and hard to detect. Also much of the oxygen is used up by respiration.

The average human exhales about 1 kg of CO2 per day, so the 7 billion humans that populate the Earth today exhale about 2.5 x 109 tons of CO2 per year, a little less than 1% of that is needed to support the primary productivity of photosynthesis and only about 6% of the CO2 “pollution” resulting from the burning of fossil fuels. However, unlike fossil fuel emissions, these human (or more generally, biological) emissions do not accumulate in the atmosphere, since the carbon in food ultimately comes from the atmosphere in the first place.

Question 7: What are the main sources of CO2 that account for the incremental buildup of CO2 in the atmosphere?

The CO2 in the atmosphere is but one reservoir within the global carbon cycle, whose stocks and flows are illustrated by Figure 6.1 from IPCC AR5 WG1:

There is a nearly-balanced annual exchange of some 200 PgC between the atmosphere and the earth’s surface (~80 Pg land and ~120 Pg ocean); the atmospheric stock of 829 Pg therefore “turns over” in about four years.

Human activities currently add 8.9 PgC each year to these closely coupled reservoirs (7.8 from fossil fuels and cement production, 1.1 from land use changes such as deforestation). About half of that is absorbed into the surface, while the balance (airborne fraction) accumulates in the atmosphere because of its multicentury lifetime there. Other reservoirs such as the intermediate and deep ocean are less closely coupled to the surface-atmosphere system.

Much of the natural emission of CO2 stems from the decay of organic matter on land, a process that depends strongly on temperature and moisture. And much CO2 is absorbed and released from the oceans, which are estimated to contain about 50 times as much CO2 as the atmosphere. In the oceans CO2 is stored mostly as bicarbonate (HCO3 – ) and carbonate (CO3 – – ) ions. Without the dissolved CO2, the mildly alkaline ocean with a pH of about 8 would be very alkaline with a pH of about 11.3 (like deadly household ammonia) because of the strong natural alkalinity.

Only once in the geological past, the Permian period about 300 million years ago, have atmospheric CO2 levels been as low as now. Life flourished abundantly during the geological past when CO2 levels were five or ten times higher than those today.

Question 8: What are the main sources of heat that account for the incremental rise in temperature on earth?

The only important primary heat source for the Earth’s surface is the Sun. But the heat can be stored in the oceans for long periods of time, even centuries. Variable ocean currents can release more or less of this stored heat episodically, leading to episodic rises (and falls) of the Earth’s surface temperature.

Incremental changes of the surface temperature anomaly can be traced back to two causes: (1) changes in the surface heating rate; (2) changes in the resistance of heat flow to space. Quasi periodic El Nino episodes are examples of the former. During an El Nino year, easterly trade winds weaken and very warm deep water, normally blown toward the coasts of Indonesia and Australia, floats to the surface and spreads eastward to replace previously cool surface waters off of South America. The average temperature anomaly can increase by 1 C or more because of the increased release of heat from the ocean. The heat source for the El Nino is solar energy that has accumulated beneath the ocean surface for several years before being released.

On average, the absorption rate of solar radiation by the Earth’s surface and atmosphere is equal to emission rate of thermal infrared radiation to space. Much of the radiation to space does not come from the surface but from greenhouse gases and clouds in the lower atmosphere, where the temperature is usually colder than the surface temperature, as shown in the figure on the previous page. The thermal radiation originates from an “escape altitude” where there is so little absorption from the overlying atmosphere that most (say half) of the radiation can escape to space with no further absorption or scattering. Adding greenhouse gases can warm the Earth’s surface by increasing the escape altitude. To maintain the same cooling rate to space, the temperature of the entire troposphere, and the surface, would have to increase to make the effective temperature at the new escape altitude the same as at the original escape altitude. For greenhouse warming to occur, a temperature profile that cools with increasing altitude is required.

Over most of the CO2 absorption band (between about 580 cm-1 and 750 cm-1 ) the escape altitude is the nearly isothermal lower stratosphere shown in the first figure. The narrow spike of radiation at about 667 cm-1 in the center of the CO2 band escapes from an altitude of around 40 km (upper stratosphere), where it is considerably warmer than the lower stratosphere due heating by solar ultraviolet light which is absorbed by ozone, O3. Only at the edges of the CO2 band (near 580 cm-1 and 750 cm-1 ) is the escape altitude in the troposphere where it could have some effect on the surface temperature. Water vapor, H2O, has emission altitudes in the troposphere over most of its absorption bands. This is mainly because water vapor, unlike CO2, is not well mixed but mostly confined to the troposphere.

Summary

To summarize this overview, the historical and geological record suggests recent changes in the climate over the past century are within the bounds of natural variability. Human influences on the climate (largely the accumulation of CO2 from fossil fuel combustion) are a physically small (1%) effect on a complex, chaotic, multicomponent and multiscale system. Unfortunately, the data and our understanding are insufficient to usefully quantify the climate’s response to human influences. However, even as human influences have quadrupled since 1950, severe weather phenomena and sea level rise show no significant trends attributable to them. Projections of future climate and weather events rely on models demonstrably unfit for the purpose. As a result, rising levels of CO2 do not obviously pose an immediate, let alone imminent, threat to the earth’s climate.

Full text of submission is here

I just found out, thanks to Francis Menton, that a third skeptical brief was submitted to Judge Alsup in reference to his tutorial.  The thrust apparently is to show that the temperature record does not support the claim that recent variability is anything out of the ordinary.

The article by Francis Menton is Klimate Kraziness: A California Judge Holds A “Tutorial” On Climate Science  posted at Manhatton Contrarian.

The third friend of the court brief  was by  The Concerned Household Electricity Consumers Council, which presented work of many scientists, most notably James Wallace III, Joseph D’Aleo, John Christie, and Craig Idso.  Menton’s explanation below from his article.

Not to downplay the work of my co-amici, but we are the one of the three groups that emphatically made the essential scientific point that the most credible data as to world temperatures, properly analyzed, preclude rejection of the null hypothesis that natural factors are the predominant if not only cause of the observed warming. As stated in our submission:

The conclusion of the work is that each of EPA’s “lines of evidence” has been invalidated by the best empirical evidence, and therefore the attribution of any observed climate change, including global warming, to rising atmospheric CO2 concentrations has not been established.

And, further on in our presentation:

[T]hese natural factor impacts fully explain the trends in all relevant temperature data sets over the last 50 or more years. This research, like Wallace (2016), found that rising atmospheric concentrations did not have a statistically significant impact on any of the (14) temperature data sets that were analyzed. Wallace 2017 concludes that, “at this point, there is no statistically valid proof that past increases in atmospheric CO2 concentrations have caused what have been officially reported as rising, or even record setting, temperatures.”

As they say, read the whole thing (here)

Footnote:

The post The Climate Story (Illustrated) provides a set of graphics making the same argument:  The temperature record does not support climate alarm.

Independently the prestigious Société de Calcul Mathématique (Society for Mathematical Calculation) has written a detailed 195-page White Paper that presents a blistering point-by-point critique of the key dogmas of global warming, starting with the temperature record.  See Bonn COP23 Briefing for Realists

Thanks to an article at Wired, we get a first glimpse into what transpired at the March 21 courtroom tutorial called by Federal District court  Judge Alsup.  From a science perspective, it looks at the moment like a missed opportunity.  The oil company lawyers sat in silence, allowing Chevron’s lead attorney to speak for them, and he mainly quoted from IPCC documents.  The calculation seems to be taking a position that we didn’t know more and not any sooner than the IPCC came to conclusions in their series of assessment reports.  The plaintiffs let alarmist scientists present on their behalf, and can now claim their opinions were not refuted.

The Wired article is In the Courtroom, Climate Science Needs Substance–and Style Excerpts below with my bolds.

Outside the usual procedural kabuki of the courtroom, the truth is no one really knew what to expect from this court-ordered “tutorial.” For a culture based in large measure on precedent, putting counsel and experts in a room to hash out climate change for a trial—putting everyone on the record, in federal court, on what is and is not true about climate science—was literally unprecedented.

What Alsup got might not have been a full on PowerPoint-powered preview of the trial. But it did reveal a lot about the styles and conflicts inherent in the people who produce the carbon and the people who study it.

The other petrochemists put forth Theodore Boutrous, an AC-130 gunship of a lawyer who among other things got the US Supreme Court to overturn the California law against same-sex marriage. Here, retained specifically by Chevron, Boutrous argued what seemed to be climate change’s chapter-and-verse. He extolled the virtues of the several IPCC reports, 2013 most recently, and quoted them liberally. Boutrous talked about how the reports’ conclusions have gotten more and more surefooted about “anthropogenic” causes of climate change—it’s people!—and outcomes like sea level rise. “From Chevron’s perspective, there’s no debate about climate science,” Boutrous said. “Chevron accepts what this scientific body—scientists and others—what the IPCC has reached consensus on.”

Still, over the course of the morning, Boutrous nevertheless tried to neg the IPCC in two specific ways. One was a classic: He challenged the models that climate scientists use to attempt to predict the future. These computer models, Boutrous said, are “increasingly complex. That can make the modeling more powerful.” But with great power comes great potential wrongness. “Because it’s an attempt to represent things in the real world, the complexity can bring more risk.” He assured the court that Chevron agreed with the IPCC approach—posting up a slide pulled from an IPCC report that showed the multicolored paths of literally hundreds of models, using different emissions scenarios and essentially describing the best case and worst case (and a bunch of in-between cases). It looked like a blast of fireworks emerging from observed average temperature, headed chaotically up and to the right.

So here comes the crux of the thing—a question not of whether climate change is real, but whether you can ascribe blame for it. Leaning heavily on more IPCC quotes, Boutrous showed slides and statistics saying that climate change is a global problem that doesn’t differentially affect the West Coast of North America and isn’t caused by any one emitter. Or even any one source of emissions. Anthropogenic emissions are driven by things like population size, economic activities, lifestyle, energy use, land use patterns, and technology and climate policy, according to the IPCC. “The IPCC does not say it’s the extraction and production of oil,” Boutrous said. “It’s economic activity that creates the demand for energy and that leads to emissions.”

If that seems a little bit like the “guns don’t kill people; people kill people” of petrochemical capitalism, well, Judge Alsup did start the morning by saying today was a day for science, not politics.

So what knives did the representatives of the state of California bring to this oil-fight? Here’s where style is interesting. California didn’t front lawyers. For the science tutorial, the municipalities fronted scientists—people who’d been first authors on chapters in the IPCC reports from which Boutrous quoted, and one who’d written a more recent US report and a study of sea level rise in California. They knew their stuff and could answer all of Judge Alsup’s questions … but their presentations were more like science conference fodder than well-designed rhetoric.

For example, Myles Allen, leader of the Climate Research Program at the University of Oxford, gave a detailed, densely-illustrated talk on the history and science of climate change…but he also ended up in an extended back and forth with Alsup about whether Svante Arrhenius’ 1896 paper hypothesizing that carbon dioxide in Earth’s atmosphere warmed the planet explicitly used the world “logarithmic.” Donald Wuebbles, an atmospheric scientist at the University of Illinois and co-author of the Nobel Prize-winning 2007 IPCC report, mounted a grim litany of all the effects scientists can see, today, of climate, but Alsup caught him up asking for specific things he disagreed with Boutrous on—a tough game since Boutrous was just quoting the IPCC.

Then Alsup and Wuebbles took a detour into naming other renewable power sources besides solar and wind. “Nuclear would not put out any CO2, right? We might get some radiation as we drive by, but maybe in retrospect we should have taken a hard look at nuclear?” Alsup interrupted. “No doubt solar is good where you can use it, but do you really think it could be a substitute for supplying the amount of power America used in the last 30 years?”

“I think solar could be a significant factor of our energy future,” Wuebbles said. “I don’t think there’s any one silver bullet.”

In part, one might be tempted to put some blame on Alsup here. You might remember him from such trials as Uber v. Waymo, where he asked for a similar tutorial on self-driving car technology. Or from Oracle v. Google, a trial for which Alsup taught himself a little of the programming language Java so he’d understand the case better. Or from his intercession against the Trump administration’s attempt to cancel the Deferred Action for Childhood Arrivals program, protecting the immigration status of so-called Dreamers. “He’s kind of quirky and not reluctant to do things kind of outside the box,” said Deborah Sivas, Director of the Environmental and Natural Resource Law & Policy Program at Stanford Law School. “And I think he sees this as a precedent-setting case, as do the lawyers.”

It’s possible, then, to infer that Alsup was doing more than just getting up to speed on climate change on Wednesday. The physics and chemistry are quite literally textbook, and throughout the presentations he often seemed to know more than he was letting on. He challenged chart after chart incisively, and often cut in on history. When Allen brought up Roger Revelle’s work showing that oceans couldn’t absorb carbon—at least, not fast enough to stave off climate change, Alsup interrupted.

“Is it true that Revelle initially thought the ocean would absorb all the excess, and that he came to this buffer theory a little later?” Alsup asked.

“You may know more of this history than I do,” Allen said.

But on the other hand, some of what the litigators seemed to not know sent the scientists in the back in literal spasms. When Boutrous couldn’t answer Alsup’s questions about the specific causes of early 20th-century warming (presumably before the big industrial buildup of the 1950s), Allen and Wuebbles, sitting just outside the gallery, clenched fists and looked like they were having to keep from shouting out the answer. Later, Alsup acknowledged that he’d watched An Inconvenient Truth to prepare, and Boutrous said he had, too.

All of which makes it hard to tell whether bringing scientists to this table was the right move. And maybe that has been the problem all along. The interface where utterly flexible law and policy moves against the more rigid statistical uncertainties of scientific observation has always been contested space. The practitioners of both arts seem foreign to each other; the cultural mores differ.

Maybe that’s what this “tutorial” was meant for. As Sivas says, the facts aren’t really in doubt here. Or rather, most of them aren’t, and maybe Alsup will use today as a kind of discovery process, a way to crystalize the difference between uncertainty in science and uncertainty under the law. “That’s what judges do. They decide the credibility of one expert over another,” Sivas says. “That doesn’t mean it’s scientific truth. It means it’s true as a legal claim.”

The skeptical scientific brief was filed by esteemed scientists Happer, Koonin and Lindzen, but its effect is not yet evident.  More details are at Cal Climate Tutorial: The Meat

Prevous posts provided the context regarding the Climate Tutorial requested by Judge Alsup in the lawsuit case filed by California cities against big oil companies: Cal Court to Hear Climate Tutorial

An overview of a submission by Professors Happer, Koonin and Lindzen was in Climate Tutorial for Judge Alsup

This post goes into the meat and potatoes of that submission with excerpts from Section II: Answers to specific questions (my bolds)

Question 1: What caused the various ice ages (including the “little ice age” and prolonged cool periods) and what caused the ice to melt? When they melted, by how much did sea level rise?

The discussion of the major ice ages of the past 700 thousand years is distinct from the discussion of the “little ice age.” The former refers to the growth of massive ice sheets (a mile or two thick) where periods of immense ice growth occurred, lasting approximately eighty thousand years, followed by warm interglacials lasting on the order of twenty thousand years. By contrast, the “little ice age” was a relatively brief period (about four hundred years) of relatively cool temperatures accompanied by the growth of alpine glaciers over much of the earth.

The last glacial episode ended somewhat irregularly. Ice coverage reached its maximum extent about eighteen thousand years ago. Melting occurred between about twenty thousand years ago and thirteen thousand years ago, and then there was a strong cooling (Younger Dryas) which ended about 11,700 years ago. Between twenty thousand years ago and six thousand years ago, there was a dramatic increase in sea level of about 120 meters followed by more gradual increase over the following several thousand years. Since the end of the “little ice age,” there has been steady increase in sea-level of about 6 inches per century.

As to the cause of the “little ice age,” this is still a matter of uncertainty. There was a long hiatus in solar activity that may have played a role, but on these relatively short time scales one can’t exclude natural internal variability. It must be emphasized that the surface of the earth is never in equilibrium with net incident solar radiation because the oceans are always carrying heat to and from the surface, and the motion systems responsible have time scales ranging from years (for example ENSO) to millennia.

The claim that orbital variability requires a boost from CO2 to drive ice ages comes from the implausible notion that what matters is the orbital variations in the global average insolation (which are, in fact, quite small) rather than the large forcing represented by the Milankovitch parameter. This situation is very different than in the recent and more modest shorter-term warming, where natural variability makes the role of CO2 much more difficult to determine.

Question 2: What is the molecular difference by which CO2 absorbs infrared radiation but oxygen and nitrogen do not?

Molecules like CO2, H2O, CO or NO are called a greenhouse-gas molecules, because they can efficiently absorb or emit infrared radiation, but they are nearly transparent to sunlight. Molecules like O2 and N2 are also nearly transparent to sunlight, but since they do not absorb or emit thermal infrared radiation very well, they are not greenhouse gases. The most important greenhouse gas, by far, is water vapor. Water molecules, H2O, are permanently bent and have large electric dipole moments.

Question 3: What is mechanism by which infrared radiation trapped by CO2 in the atmosphere is turned into heat and finds its way back to sea level?

Unscattered infrared radiation is very good at transmitting energy because it moves at the speed of light. But the energy per unit volume stored by the thermal radiation in the Earth’s atmosphere is completely negligible compared to the internal energy of the air molecules.

Although CO2 molecules radiate very slowly, there are so many CO2 molecules that they produce lots of radiation, and some of this radiation reaches sea level. The figure following shows downwelling radiation measured at the island of Nauru in the Tropical Western Pacific Ocean, and at colder Point Barrow, Alaska, on the shore of the Arctic Ocean.

So the answer to the last part of the question, “What is the mechanism by which … heat … finds its way back to sea level?” is that the heat is radiated to the ground by molecules at various altitudes, where there is usually a range of different temperatures. The emission altitude is the height from which radiation could reach the surface without much absorption, say 50% absorption. For strongly absorbed frequencies, the radiation reaching the ground comes from low-altitude molecules, only a few meters above ground level for the 667 cm-1 frequency at the center of the CO2 band. More weakly absorbed frequencies are radiated from higher altitudes where the temperature is usually colder than that of the surface. But occasionally, as the data from Point Barrow show, higher-altitude air can be warmer than the surface.

Closely related to Question 3 is how heat from the absorption of sunlight by the surface gets back to space to avoid a steadily increasing surface temperature. As one might surmise from the figure, at Narau there is so much absorption from CO2 and by water vapor, H2O, that most daytime heat transfer near the surface is by convection, not by radiation. Especially important is moist convection, where the water vapor in rising moist air releases its latent heat to form clouds. The clouds have a major effect on radiative heat transfer. Cooled, drier, subsiding air completes the convection circuit. Minor changes of convection and cloudiness can have a bigger effect on the surface temperature than large changes in CO2 concentrations.

Question 4: Does CO2 in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?

The short answer to this question is “No”, but it raises some interesting issues that we discuss below.

Molecules can either scatter or absorb radiation. CO2 molecules are good absorbers of thermal infrared radiation, but they scatter almost none. Infrared radiant energy absorbed by a CO2 molecule is converted to internal vibrational and rotational energy. This internal energy is quickly lost in collisions with the N2 and O2 molecules that make up most of the atmosphere. The collision rates, billions per second, are much too fast to allow the CO2 molecules to reradiate the absorbed energy, which takes about a second. CO2 molecules in the atmosphere do emit thermal infrared radiation continuously, but the energy is almost always provided by collisions with N2 and O2 molecules, not by previously absorbed radiation. The molecules “glow in the dark” with thermal infrared radiation.

The figure shows that water vapor is by far the most important absorber. It can absorb both thermal infrared radiation from the Earth and shorter-wave radiation from the Sun. Water vapor and its condensates, clouds of liquid or solid water (ice), dominate radiative heat transfer in the Earth’s atmosphere; CO2 is of secondary importance.

If Question 4 were “Do clouds in the atmosphere reflect any sunlight back into space, such that the reflected sunlight never penetrates the atmosphere in the first place?” the answer would be “Yes”. It is common knowledge that low clouds on a sunny day shade and cool the surface of the Earth by scattering the sunlight back to space before it can be absorbed and converted to heat at the surface.

The figure shows that very little thermal radiation from the surface can reach the top of the atmosphere without absorption, even if there are no clouds. But some of the surface radiation is replaced by molecular radiation emitted by greenhouse molecules or cloud tops at sufficiently high altitudes that the there are no longer enough higher-altitude greenhouse molecules or clouds to appreciably attenuate the radiation before it escapes to space. Since the replacement radiation comes from colder, higher altitudes, it is less intense and does not reject as much heat to space as the warmer surface could have without greenhousegas absorption.

As implied by the figure, sunlight contains some thermal infrared energy that can be absorbed by CO2. But only about 5% of sunlight has wavelengths longer than 3 micrometers where the strongest absorption bands of CO2 are located. The Sun is so hot, that most of its radiation is at visible and near-visible wavelengths, where CO2 has no absorption bands.

Question 5: Apart from CO2, what happens to the collective heat from tail pipe exhausts, engine radiators, and all other heat from combustion of fossil fuels? How, if at all, does this collective heat contribute to warming of the atmosphere?

After that energy is used for heat, mobility, and 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 IR emissions. [A very small fraction winds up as visible light that escapes directly to space through the transparent atmosphere, but even that ultimately winds up as heat somewhere “out there.”]

How much does this anthropogenic heat affect the climate? There are local effects where energy use is concentrated, for example in cities and near power plants. But globally, the effects are very small. To see that, convert the global annual energy consumption of 13.3 Gtoe (Gigatons of oil equivalent) to 5.6 × 10^20 joules. Dividing that by the 3.2 × 10^7 seconds in a year gives a global power consumption of 1.75 × 10^13 Watts. Spreading that over the earth’s surface area of 5.1 × 10^14 m2 results in an anthropogenic heat flux of 0.03 W/m2 . This is some four orders of magnitude smaller than the natural heat fluxes of the climate system, and some two orders of magnitude smaller than the anthropogenic radiative forcing.

Question 6: In grade school many of us were taught that humans exhale CO2 but plants absorb CO2 and return oxygen to the air (keeping the carbon fiber). Is this still valid? If so why hasn’t plant life turned the higher levels of CO2 back into oxygen? Given the increase in population on earth (four billion), is human respiration a contributing factor to the buildup of CO2?

If all of the CO2 produced by current combustion of fossil fuels remained in the atmosphere, the level would increase by about 4 ppm per year, substantially more than the observed rate of around 2.5 ppm per year, as seen in the figure above. Some of the anthropogenic CO2 emissions are being sequestered on land or in the oceans.

There is evidence that primary photosynthetic productivity has increased somewhat over the past half century, perhaps due to more CO2 in the atmosphere. For example, the summerwinter swings like those in the figure above are increasing in amplitude. Other evidence for modestly increasing primary productivity includes the pronounced “greening” of the Earth that has been observe by satellites. An example is the map above, which shows a general increase in vegetation cover over the past three decades.

The primary productivity estimate mentioned above would also correspond to an increase of the oxygen fraction of the air by 50 ppm, but since the oxygen fraction of the air is very high (209,500 ppm), the relative increase would be small and hard to detect. Also much of the oxygen is used up by respiration.

The average human exhales about 1 kg of CO2 per day, so the 7 billion humans that populate the Earth today exhale about 2.5 x 10^9 tons of CO2 per year, a little less than 1% of that is needed to support the primary productivity of photosynthesis and only about 6% of the CO2 “pollution” resulting from the burning of fossil fuels. However, unlike fossil fuel emissions, these human (or more generally, biological) emissions do not accumulate in the atmosphere, since the carbon in food ultimately comes from the atmosphere in the first place.

Question 7: What are the main sources of CO2 that account for the incremental buildup of CO2 in the atmosphere?

The CO2 in the atmosphere is but one reservoir within the global carbon cycle, whose stocks and flows are illustrated by Figure 6.1 from IPCC AR5 WG1:

There is a nearly-balanced annual exchange of some 200 PgC between the atmosphere and the earth’s surface (~80 Pg land and ~120 Pg ocean); the atmospheric stock of 829 Pg therefore “turns over” in about four years.

Human activities currently add 8.9 PgC each year to these closely coupled reservoirs (7.8 from fossil fuels and cement production, 1.1 from land use changes such as deforestation). About half of that is absorbed into the surface, while the balance (airborne fraction) accumulates in the atmosphere because of its multicentury lifetime there. Other reservoirs such as the intermediate and deep ocean are less closely coupled to the surface-atmosphere system.

Much of the natural emission of CO2 stems from the decay of organic matter on land, a process that depends strongly on temperature and moisture. And much CO2 is absorbed and released from the oceans, which are estimated to contain about 50 times as much CO2 as the atmosphere. In the oceans CO2 is stored mostly as bicarbonate (HCO3 – ) and carbonate (CO3 – – ) ions. Without the dissolved CO2, the mildly alkaline ocean with a pH of about 8 would be very alkaline with a pH of about 11.3 (like deadly household ammonia) because of the strong natural alkalinity.

Only once in the geological past, the Permian period about 300 million years ago, have atmospheric CO2 levels been as low as now. Life flourished abundantly during the geological past when CO2 levels were five or ten times higher than those today.

Question 8: What are the main sources of heat that account for the incremental rise in temperature on earth?

The only important primary heat source for the Earth’s surface is the Sun. But the heat can be stored in the oceans for long periods of time, even centuries. Variable ocean currents can release more or less of this stored heat episodically, leading to episodic rises (and falls) of the Earth’s surface temperature.

Incremental changes of the surface temperature anomaly can be traced back to two causes: (1) changes in the surface heating rate; (2) changes in the resistance of heat flow to space. Quasi periodic El Nino episodes are examples of the former. During an El Nino year, easterly trade winds weaken and very warm deep water, normally blown toward the coasts of Indonesia and Australia, floats to the surface and spreads eastward to replace previously cool surface waters off of South America. The average temperature anomaly can increase by 1 C or more because of the increased release of heat from the ocean. The heat source for the El Nino is solar energy that has accumulated beneath the ocean surface for several years before being released.

On average, the absorption rate of solar radiation by the Earth’s surface and atmosphere is equal to emission rate of thermal infrared radiation to space. Much of the radiation to space does not come from the surface but from greenhouse gases and clouds in the lower atmosphere, where the temperature is usually colder than the surface temperature, as shown in the figure on the previous page. The thermal radiation originates from an “escape altitude” where there is so little absorption from the overlying atmosphere that most (say half) of the radiation can escape to space with no further absorption or scattering. Adding greenhouse gases can warm the Earth’s surface by increasing the escape altitude. To maintain the same cooling rate to space, the temperature of the entire troposphere, and the surface, would have to increase to make the effective temperature at the new escape altitude the same as at the original escape altitude. For greenhouse warming to occur, a temperature profile that cools with increasing altitude is required.

Over most of the CO2 absorption band (between about 580 cm-1 and 750 cm-1 ) the escape altitude is the nearly isothermal lower stratosphere shown in the first figure. The narrow spike of radiation at about 667 cm-1 in the center of the CO2 band escapes from an altitude of around 40 km (upper stratosphere), where it is considerably warmer than the lower stratosphere due heating by solar ultraviolet light which is absorbed by ozone, O3. Only at the edges of the CO2 band (near 580 cm-1 and 750 cm-1 ) is the escape altitude in the troposphere where it could have some effect on the surface temperature. Water vapor, H2O, has emission altitudes in the troposphere over most of its absorption bands. This is mainly because water vapor, unlike CO2, is not well mixed but mostly confined to the troposphere.

Summary

To summarize this overview, the historical and geological record suggests recent changes in the climate over the past century are within the bounds of natural variability. Human influences on the climate (largely the accumulation of CO2 from fossil fuel combustion) are a physically small (1%) effect on a complex, chaotic, multicomponent and multiscale system. Unfortunately, the data and our understanding are insufficient to usefully quantify the climate’s response to human influences. However, even as human influences have quadrupled since 1950, severe weather phenomena and sea level rise show no significant trends attributable to them. Projections of future climate and weather events rely on models demonstrably unfit for the purpose. As a result, rising levels of CO2 do not obviously pose an immediate, let alone imminent, threat to the earth’s climate.

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