Reducing CO2 Emissions to Reverse Global Warming

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Reducing CO2 Emissions to Reverse Global Warming

We know that Global Warming can be reduced during the years of the century ahead of us if we — our civilization — steadily reduces its emissions of carbon dioxide gas (CO2) into the atmosphere.

Given a specific rate for the reduction of anthropogenic (our CO2) emissions:

— how long will it take to return Earth’s average temperature to its unperturbed pre-industrial level?, and

— how much higher will Global Warming (Earth’s temperature) become before it begins to decrease?

Answering these questions is the subject of my recent study. This work is based on a Carbon Balance Model, which I described in an earlier report. [1]

That model has been further refined in order to address these questions, and the details of that refinement are described in a technical report. [2]

Prior to the buildup of anthropogenic CO2 emissions in the air, the fluxes of CO2 released by the respiration of Life-on-Earth; and the fluxes of CO2 absorbed from the air by photosynthesis, the surface waters of the oceans, and rock weathering chemical reactions; were in balance. That balance is known as the Carbon Cycle.

As the rate and buildup of anthropogenic emissions increased (after ~1750, but particularly from the mid-20th century), the Carbon Cycle was perturbed out of balance, and the magnitude of that imbalance is determined by the difference between two effects: Anthropogenic Sources, and Stimulated Sinks.

The Anthropogenic Sources are:

— the CO2 emissions by the human activities of fossil-fueled energy generation and industry, and

— the CO2 emissions from land use changes (deforestation and its attendant increase of wildfires).

The Stimulated Sinks are the additional absorption of CO2 by photosynthesis and the surface waters of the oceans, because of higher atmospheric concentrations of CO2. At a sufficiently high level of atmospheric CO2 concentration, both these sinks will saturate — stop absorbing CO2. What that “sufficiently high level” is remains uncertain.

The work summarized here includes more realistic (more complicated) models of these source and sink terms in the rate equation for the change of the Carbon Balance over time.

Now I am able to quantitatively link specific rates of the reduction of anthropogenic CO2 emissions, to consequent projected histories of the slowing and then reversal of Global Warming.

Such quantitative linkages have long been featured in the super-computer models of CO2 accumulation in the atmosphere, by the major Climate Science institutes; but now I have my own quantitative version of this correlation, which is analytical (expressed as math formulas, and enumerated with a hand calculator and basic home computer).

Anthropogenic CO2 emissions in year 2020 are 42.2GtCO2/y (42.2 giga-metric-tons of CO2 per year = 42.2*10^+12 kilograms/year). This magnitude of total anthropogenic emissions, E, is the addition of our fossil-fueled and land use emissions.

I considered three cases of the intentional steady reduction of annual human-caused CO2 emissions, which are defined to decrease exponentially. The characteristic decay time of each case is: 40 years (CASE 1, a 2.5% annual reduction), 100 years (CASE 2, a 1% annual reduction), and 200 years (CASE 3, a 0.5% annual reduction).

Emissions would be reduced to half their initial rate in 28 years for CASE 1; in 69 years for CASE 2; and in 139 years for CASE 3.

If each of these reduction plans were alternatively initiated in the year 2020, then:

CASE #1, ∆t=40y:

This trend reaches a peak of 449ppm and +1.32°C in year 2048 (in 28 years); it remains above 440ppm and +1.25°C over the years 2032 to 2064 (between 12 to 44 years from now); then descends to 350ppm and +0.56°C in year 2120 (in 100 years); and 300ppm and +0.18°C in year 2140 (in 120 years).

CASE #2, ∆t=100y:

This trend reaches a peak plateau of 485ppm and +1.6°C over the years 2078 to 2088 (between 58 and 68 years from now); it remains above 480ppm and +1.56°C during years 2066 to 2100 (between 46 and 80 years from now); it descends to 350ppm and +0.56°C in year 2202 (in 182 years); and 300ppm and +0.18°C in year 2225 (in 205 years).

CASE #3, ∆t=200y:

This trend reaches a peak plateau of 524ppm and +1.9°C over the years 2125 to 2135 (between 105 and 115 years from now); it remains above 500ppm and +1.72°C between years 2075 and 2190 (between 55 and 170 years from now); and descends down to 360ppm and +0.64°C in year 2300 (in 280 years).

Message to the Humans

The singular challenge for the progressive political and social elements of our civilization is to awaken the rest of the world — and particularly the “developed” and “developing” high-emissions nations — to a full commitment (demonstrated by action) to steadily and significantly reduce anthropogenic CO2 emissions for the rest of human history.

The sooner such reduction programs are initiated, and the greater the vigor with which they are implemented, the sooner we will begin slowing the advance of Global Warming and its continuing erosion of the habitability of Planet Earth, which humans have enjoyed for over 2 million years, and particularly since the end of the Ice Ages (~11,000 year ago).

With decades to a century of discipline applied to this purpose, we can even reverse Global Warming. The longer we wait to do this, the worse the consequences we will have to suffer through, and the longer it would take to extricate our species — and so many other wonderful forms of Life-on-Earth — from the Hell-on-Earth we are creating by our willful and destructive ignorance.

I can only imagine such major programs of CO2 emissions reductions being synonymous with the economic, political and social uplift of the vast majority of people, because Global Warming is directly caused by the unbounded economic, political and social exploitation of the many by the few.

The fact is that we all live on the same planet, and whatever happens to it — whether worsening conflagration and flooding in the now, or eventual cooling and restoration by human commitment — will affect everybody. There is no guaranteed escape.

The CO2 accumulation model that I have described here is just this old scientist’s way of saying: We can do so much better for ourselves, and our children deserve that we try.

NOTES

[1] A Carbon Balance Model of Atmospheric CO2
11 September 2020, [PDF file]
https://manuelgarciajr.files.wordpress.com/2020/09/a-carbon-balance-model-of-atmospheric-co2.pdf

[2] Trends for Reducing Global Warming
15 September 2020, [PDF file]
https://manuelgarciajr.files.wordpress.com/2020/09/trends-for-reducing-global-warming.pdf

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Anthropogenic CO2 Emissions Are Fate

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Anthropogenic CO2 Emissions Are Fate

I developed a model of Global Warming based on the anthropogenic perturbation of the Carbon Cycle. The essence of this model is a rate equation for the evolution of the carbon dioxide (CO2) concentration in the atmosphere.

The interesting results from this model are projected trends for the CO2 concentration and the average global temperature during the next century. The character of those trends — whether rapid rises, shallow plateaus, or diminishment into the future — depend crucially on the magnitude of our civilization’s emissions of CO2, and whether those anthropogenic emissions increase or decrease with time. In the real world at present, they are increasing.

I have now been able to include the effect of linearly increasing or decreasing anthropogenic emissions into my Carbon Balance Model, which has been significantly improved.

This model also includes the effect of the increase in the rate at which atmospheric CO2 is absorbed by photosynthesis and the surface waters of the oceans, because those absorption rates are increasingly stimulated by the higher levels of CO2 in the air. This process of absorption-enhancement cannot continue indefinitely as the atmospheric CO2 concentration increases, but at what point of elevated CO2 concentration it saturates and then absorption largely shuts down, is unknown.

The third process included in the model is that of the slow absorption of atmospheric CO2 by the chemical reactions of weathering on the surfaces of rocks and soils. CO2 not “quickly” scavenged from the air by photosynthesis or the surface waters of the oceans will stay airborne for 12,000 to 14,000 years. The ~2,500ppm spike of atmospheric CO2 that occurred 55.5 million years ago took 200,000 years to clear away. That geological episode is known as the Paleocene-Eocene Thermal Maximum (PETM). At that time there was no ice at the poles, instead they were jungles and swamps with crocodiles. The global temperature at the peak of the PETM was as much as +12°C to +18°C warmer than in our pre-industrial 18th century.

I made three case studies from this model, called E-growth, E-flat, and E-fall.

E-growth

The E-growth case is driven by a relentlessly steady rise of anthropogenic CO2 emissions, based on the average upward trend of those emissions between years 1960 and 2020.

This trend arrives at 470ppm of atmospheric CO2, and a warming of +1.5°C (above pre-industrialization), in the year 2038 (in 18 years). It arrives 540ppm and +2°C in year 2055 (in 35 years); and it arrives at 800ppm and +4°C in year 2100 (in 80 years).

E-flat

The E-flat case is driven by a constant annual rate of 42.2GtCO2/y of anthropogenic emissions (42.2 giga-metric-tons of CO2 emissions per year), which is the rate in year 2020.

It arrives at 470ppm and +1.5°C in year 2041 (in 21 years); and 540ppm and +2°C in year 2070 (in 50 years); and 600ppm and +2.5°C in year 2100 (in 80 years).

E-fall

The E-fall case is driven by a steady linear reduction of anthropogenic emissions over 40 years: from 42.2GtCO2/y in 2020, to 0GtCO2/y in 2060; a reduction of 1.05GtCO2 every year for 40 years. This amount of annual reduction is 2.5% of the total anthropogenic emissions in year 2020. In this scenario, after year 2060 we would continue our civilization with zero CO2 emissions from our human activities.

This trend rises to 437ppm and +1.23°C during years 2035 to 2040 (from 15 to 20 years in the future) after which both fall. It arrives back down to 407ppm and +1°C in year 2059 (in 39 years); and 320ppm and +0.4°C in year 2100 (in 80 years).

Finally

In this year of 2020, we are presently at 417ppm and +1.08°C.

The math and physics details of this new work, as well as graphs of the trends calculated from it, are shown in the report (PDF file) linked at

A Carbon Balance Model of Atmospheric CO2
11 September 2020

Click to access a-carbon-balance-model-of-atmospheric-co2.pdf

 

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Possible Future Trends of CO2 Concentration and Global Temperature

Oakland, California, 10:15 AM, 9 September 2020, “Burning Land Eclipse”

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Possible Future Trends of CO2 Concentration and Global Temperature

Carbon dioxide gas (CO2) has been accumulating in the atmosphere since the dawn of the Industrial Revolution (~1750), because increasingly voluminous fluxes of that gas have been exhausted from the lands and the oceans, and are beyond the capacity of natural CO2 sinks to absorb completely.

Prior to the Industrial Revolution, carbon would cycle through a variety of processes that sustained the continuation of life, death, evolution and rebirth, and that all meshed into one grand balance. That balance is called the Carbon Cycle.

The explosive growth of human activity, numbers, exosomatic power, economic wealth, military overkill, and hubristic political pretensions, all spring from the access to and profligate use of heat-energy liberated from fossil fuels. Carbon dioxide is the exhaust fume from our Promethean exertions for greater conquests — and wealth.

The carbon dioxide exhausted by our civilization’s generation of heat-energy, and from our massive exploitation of once virgin land areas, is an increasingly destabilizing perturbation of the Carbon Cycle. This perturbation is called Anthropogenic Emissions.

The imbalance of the Carbon Cycle reverberates through the natural world in many ways that are increasingly harmful and dangerous to Planet Earth’s habitability for ourselves and for many other animal and plant species. The central reality of this complex of growing threats to the viability of the Biosphere is called Global Warming.

Carbon dioxide gas traps heat radiated towards space, as infrared radiation from the surface of Planet Earth, reducing our planet’s ability to regulate its temperature by cooling to compensate for the influx of solar light that is absorbed by the lands and the oceans, and stored by them as heat.

Because of the existential implications of runaway global warming — as well as the intrinsic fascination to curious minds of such a richly complex and grand human-entwined natural phenomenon — scientists have been studying global warming, and its impact on the biosphere, which is called Climate Change.

While scientists of all kinds are excited to share their findings on climate change and impress their colleagues with their new insights, members of the public are singularly interested to know how climate change will affect their personal futures. Can science offer them clear and reliable answers to their questions — and fears — and provide practical remedies and technological inoculations to ward off the threats by climate change to our existing ways of life?

Science does what it can to offer practical insights and helpful recommendations, and humanity does what it usually does when faced with a collective existential crisis: it hides from the inconvenience of drastically changing its personal attitudes and societal structures, which is in fact the only way it would be able to navigate the majority of Earth’s people through the transition to a new social paradigm; a new, sustainable and harmonious relationship between human life and Planet Earth.

While I am grateful to all the professional climate scientists — and their related life scientists who study many aspects of this complex of geophysical processes and biological organisms and systems — for making known so much of the workings of the globally warming biosphere, I am nevertheless curious to gain a quantitative understanding of it all for myself. To that end, I have devised my own phenomenological thermodynamic “toy models” of global warming. The sequence of my reports charting the evolution of my quantitative understanding of global warming, are listed at [1].

My newest report describes a rate equation for the accumulation or loss of atmospheric CO2 over the course of future time. This equation is derived from considerations of recent data on the Carbon Cycle (from the Global Climate Project), along with some mathematical assumptions about the relationships used to quantify “carbon dioxide sweepers,” the processes that scavenge atmospheric CO2.

The results of this work are projections of possible future histories of the concentration of atmospheric carbon dioxide, as well as a projection of the most likely trend of rising average global temperature.

The complete report on the new work (of which this is just a brief summary) is available at [2].

As is true of all future-casts, we will just have to wait till then to see if they were accurate, assuming we don’t do anything beforehand — collectively — to avoid the worst possibilities.

Such is the dance with the chaos and nonlinearity of the approaching future.

From the general mathematical result of this model, three possible future trends of CO2 concentration history were calculated:

CASE #1, “business as usual,” anthropogenic emissions continue at today’s level indefinitely;

CASE #2, anthropogenic emissions are immediately reduced to the point of holding CO2 concentration constant at today’s level, indefinitely;

CASE #3, anthropogenic emissions are immediately reduced to a trickle, so as to reduce the excess of CO2 in the atmosphere as quickly as possible.

Also, the trend of rising global temperature that accompanies CASE #1 was calculated.

CASE #1 is a pure growth trend, from 407.4ppm to 851.8ppm over the course of about 3,000 years (ppm = parts per million of concentration in the atmosphere).

CASE #2 requires that the anthropogenic emission rate be ~50% of the current rate (or 21GtCO2/y instead of 41GtCO2/y; for the units GtCO2/y defined as giga-metric-tonnes of CO2 emission per year).

This reduced rate of anthropogenic emission would just keep the CO2 concentration at 407.4ppm (from the beginning of 2019) into the near distant future (~1,600 years, and beyond), during which time the excess heat-energy presently in the biosphere would continue to degrade our weather, climate, environments, biodiversity, and planetary habitability.

CASE #3 would clear away the current excess of CO2 in the atmosphere, and then continue to reduce the atmospheric CO2 concentration to a very low level over the course of about 700 years. This would require that anthropogenic emissions be immediately reduced to about one-fifth (1/5) of their current levels, and maintained at or below that level indefinitely.

The implication is clear: if we wish to reduce the amount of CO2 in the atmosphere we have to reduce our anthropogenic emissions well below 50% of what they are today, maintain that discipline indefinitely, and wait centuries to millennia to achieve a significant reduction.

The global temperature excursion (above the average global temperature of the pre-industrial world) that accompanies CASE #1 rises steadily, though at a diminishing rate, from +1°C in 2019, to nearly +2.6°C in 2300 (~300 years). Along the way it passes +1.5°C in year 2065 (in ~40 years), and it passes +2°C in year 2120 (in ~100 years).

Global temperature would rise higher and sooner if the absorption rates of CO2 by photosynthesis and the oceans did not continue increasing — as they do today — in proportion to the increases in the atmospheric concentration of CO2. At present, increased CO2 concentration stimulates increased CO2 absorption. The model here assumes this is always true, but in reality this “sink growth” effect may saturate (be limited) at some higher level of CO2 concentration. Whether any such saturation limit on the absorption (sink) rate exists or not, is unknown.

If the +1.5°C and +2°C temperature rise milestones are truly to be avoided then it is imperative that anthropogenic emissions be drastically reduced immediately. As yet there is no sign that such reductions will occur.

The physics and mathematics of all this are fascinating, but the implications for civilization and life-on-Earth are stark.

NOTES

[1] One Year of Global Warming Reports by MG,Jr.
15 July 2020
https://manuelgarciajr.com/2020/07/15/one-year-of-global-warming-reports-by-mgjr/
Updated to 7 September 2020

[2] A Rate Equation for Accumulation or Loss of Atmospheric CO2
5 September 2020 (revised 9 September 2020)
[take a copy]
Rate Equation for Atmospheric CO2 (revised)

or view directly:

Click to access rate-equation-for-atmospheric-co2-revised.pdf

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From Caesar’s Last Breath To Ours

After the career: books donated in 2019.

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From Caesar’s Last Breath To Ours

Human Life is a sexually transmitted planetary disease, Climate Change is the disinfectant that will cure it. (I’ll explain myself on this later.)

Sam Kean’s concluding 5 paragraphs, on CO2 in the atmosphere, from his book Caesar’s Last Breath (And Other True Tales of History, Science, and the Sextillions of Molecules in the Air Around Us, 2017, Back Bay Books, Little Brown & Co) are interesting, being a series of statements of long-known physical quantities. Since I studied “gas physics” for my graduate studies (in the 1970s), and I developed an interest in climate change at least by 2004 (when I published my first article on climate change), I’ve known the basic facts Kean commented on for quite some time.

In one of my technical books on gas physics (Introduction to Physical Gas Dynamics, by Walter G. Vincenti and Charles H. Kruger, 1965, John Wiley & Sons, NY) an example is given in which the authors illustrate the physical phenomena of gaseous diffusion by showing that the last breath expelled by Julius Caeser will have taken years to fully disperse in a homogenous manner throughout the earth’s atmosphere, and so each person ‘today’ would likely breath in, on average, 5 molecules of that last breath. One amazing feature of the example is that it shows just how many molecules there are in each cubic meter of air (at sea level and ‘normal’ temperature), 2.69×10^25 per meter^3 = 2.69×10^19 per cm^3. Vincenti and Kruger quote the following from James Jeans’ 1940 book An Introduction to the Kinetic Theory of Gases (Cambridge University Press):

“…, a man is known to breath out about 400 c.c. of air at each breath, so that a single breath of air must contain about 10^22 molecules. The whole atmosphere of the earth consists of about 10^44 molecules. Thus one molecule bears the same relation to a breath of air as the latter does to the whole atmosphere of the earth. If we assume that the last breath of, say, Julius Caesar has by now become thoroughly scattered through the atmosphere, then the chances are that each of us inhales one molecule of it with every breath we take. A man’s lungs hold about 2000 c.c. of air, so that the chances are that in the lungs of each of us there are about five molecules from the last breath of Julius Caesar.”

The average spacing between air molecules (at sea level, or “standard temperature and pressure” = STP) is about 3.3×10^-7 centimeters. Since air molecules travel at an average speed of 5×10^4 centimeters/second (at STP), and each such molecule travels an average distance of 6×10^-6 centimeters before colliding into another molecule (obviously whizzing by many others between collisions), the frequency of collisions per molecule is about 10^10 collisions/second, or about 10 collisions per nanosecond.

Each such collision will deflect the colliding molecules into new directions of travel, so it can take them a very long time to actually transport from Point A to Point B separated by global distances. One number bandied about by commentators on climate change (who at least halfway know what they’re talking about) is that it takes “30 years” for local CO2 emissions to begin having a “global effect” as part of global warming. This is basically the timescale of atmospheric homogenization by diffusion of the locally emitted plumes, because of course the individual CO2 molecules of such plumes are quite ready to absorb infrared radiation, and lose it as heat released to other air molecules during collisions (the actual mechanics of global warming) from the instant those CO2 molecules are formed.

A different indicator of atmospheric trace gas homogenization is that a uniform (independent of geographical location) quantity per unit mass of radioactive fallout absorption/take-up by trees was first measured (recently, from tree corings) to have occurred in late 1965. Radioactive fallout was first created in 1945, and the greatest number of atmospheric (and any) nuclear explosions, by far, occurred in 1962. Some geologists have now proposed labeling the beginning of the Anthropocene from late 1965, and calling that year the end of the Holocene (which is/was the current geological epoch, which began with the last glacial period/retreat approximately 11,650 years ago). “Anthropocene” because it is the first epoch in which human activity (anthropo) has a global geophysical impact; such impacts being worldwide nuclear fallout (as in the 1957 book and 1959 movie On The Beach), and anthropogenic CO2/greenhouse gas-driven global warming.

When I first wrote about global warming/climate change, it was out of this perspective as a gas physicist trying to explain the technical details to a lay audience. I soon learned that the audience was not only laying, but snoring. I was trying to prod “people” into action to forestall climate change by “greening” energy technology, since I was also an engineer focused on “energy” and “efficiency.” Plus I was hoping a huge public shift in this direction would open up some nice ($$$) job opportunities for me. But the snoozing audience just wants consumerism at the lowest common denominator level, and the Big Bosses just want bombs (and money for themselves). So no sweet high-tech green-physics job for me, but more firepower for the ‘criminalated’ psychopaths who are our guiding self-worshipping self-imagined Olympians, more gargantuan Black Friday tsunamis of electro-plastic garbage consumerism for the ‘amnesiatariat,’ and as a result giga-tons more carbonation of the atmosphere and acidification of the seas, and less viability for our planet with its growing human population.

Since “the human element” (mental inertia, ego, tribalism) always controls and limits the actualization of any technical enterprise by a group of people — like greening away from fossil fuels — it was quickly obvious to me that though most “solar energy” technologies were ancient and well-understood “we” were not going to give up fossil fuel convenience, wealth-generation and enablement-of-political-power in favor of green energy, and so consequently global warming could only increase. And it has, and will. So I write about climate change “for the art of it” and for personal satisfaction, in particular to put my views “on the record” for my children. But I can only fantasize, without belief, that such writing will have any practical political effect — of course I’d like it to, but I’m a realist. Happily, it’s always nice to hear every now and then from someone who already agrees with my views, that something I’ve written has given them some encouragement.

And that is where the arc of my climate change consciousness — from the science to our society — has brought me to today: human connection. Given that fossil fueled humanity is intransigent, and now the advance of climate change is implacable (“tipping points”), I see the best focus for most people’s limited energies beyond their immediate survival and family needs to be the developing of a consciousness of climate change and political reality, and a commitment to acting toward others at a minimum with benign neutrality and better yet with compassion, honesty and solidarity, so human society is generally improved and economically more leveled, regardless of the geophysical conditions under which it exists at any given time. For a society that is as deeply humane as I’ve suggested (and vastly different than today’s) then if and when we really do enter a rapidly accelerating “end time” our individual exits would be as decently humane as possible because they would be occurring within a societal death-with-dignity of a society of broad solidarity. I suppose this is kind of glum thinking, but maybe that’s an inevitable result of my growing ‘old’ in these times.

All this has been a rather prolix introduction to a video about climate change I thought you might enjoy. The Age Of Stupid is a 90 minute British documentary from 2009 (five years in the making) that remains brilliantly cogent about the “human element” driving the climate change geophysics, and is also refreshingly accurate about the physical details of that geophysics. [1] The Age Of Stupid Revisited is a 15 minute look back on the original documentary, from today. [2] Nothing has changed for the better; for the worse yes. Reflecting on this documentary, on the arc of my climate change consciousness, and on my belief (which I wish future reality would contradict) that there will never be any significant collective action to stop anthropo-exacerbation of climate change, and to also end poverty and to economically level national and world societies, I arrived at the rather tart characterization that: human life is a sexually transmitted planetary disease, and climate change is the disinfectant that will cure it.

Notes

[1] The Age of Stupid
2009
https://youtu.be/awVbLg59tR8

[2] The Age of Stupid revisited: what’s changed on climate change?
15 March 2019
https://youtu.be/GqHKYwxEIRA

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My CO2 Automobile Emissions

1) I have driven automobiles around the world 30 times.
2) Total distance is 750,000 miles.
3a) Speed was 2/3 of a circuit per year [1],
3b) or 16,667 miles/year (45 years),
3c) or 45.6… miles/day (45 years).
4a) Fuel used was 30,000 gallons of gasoline
4b) at 25 mpg (assumed).
5a) CO2 produced was 589,200 pounds [2],
5b) or 13,093.3… pounds/year, 45 years.
6) Number of travellers 1 to 5 (average ~2).
7) CO2/average traveller is 6,546.6… pound/year.
8) CO2/mile is 0.7856 pounds/mile.
9) Equivalent # US drivers/year, if use my rate of CO2 production = 143 million. [3]
10) Average # cars/trucks owned per Equivalent driver = 1.78. [4]

DATA:

[1] Circumference of the Earth is 24,901 miles (rounded up to 25 kmile).

[2] “About 19.64 pounds of carbon dioxide (CO2) are produced from burning a gallon of gasoline that does not contain ethanol.” (US-EIA)

[3] US CO2 from autos and gasoline powered trucks is >50%, probably <66%, of the CO2 emissions from the entire transportation sector, which produces 26% of the total US emission of CO2 (2014, but similar since 1990). The total greenhouse gas emissions for the US (2014) is 6870 x 10^6 metric tons, and CO2 is 82% of that greenhouse gas total. (US-EPA). [1 metric ton (1000 kg) = 2204 pounds.] So:

a1) Total greenhouse gas/year = 6,870 million metric tonnes.
a2) Total greenhouse gas/year = 15,141,480 million pounds
(15.141 trillion pounds).

b1) Total CO2/year = 5633 million metric tonnes.
b2) Total CO2/year = 12,416,013 million pounds
(12.416 trillion pounds).

c1) Transportation CO2/year = 1465 million metric tonnes.
c2) Transportation CO2/year = 3,228,163 million pounds
(3.228 trillion pounds).

d1) Auto/truck CO2/year (@ 58%) = 849.5 million metric tonnes.
d2) Auto/truck CO2/year (@ 58%) = 1,872,334 million pounds
(1.872 trillion pounds).

[4] “According to the Bureau of Transportation Statistics for 2012, there were 254,639,386 registered vehicles” in the U.S. (rounded up to 255 million) (wikipedia)