The CO2 Bathtub

Summary:  Previous postings have detailed the findings that a) even if humanity stops burning fossil fuels that produce atmospheric CO2, simply continuing to use existing facilities, such as power plants and automobiles, will add new CO2 to the atmosphere for several decades and lead to increased warming of the planet; and b) in reality, humanity’s demand for ever increasing amounts of energy will lead to much higher levels of atmospheric CO2 over the coming decades than at present.  In order to visualize this, here we imagine that the atmosphere is a bathtub containing CO2 at the present concentration.  We assess the factors that cause the bathtub to add more CO2 or that help drain it.  As noted, the bathtub will fill with more CO2 in coming decades. This model shows clearly that it is not enough merely to cut back on CO2 production, but that it is critical to cease completely the burning of fossil fuels for energy as soon as practical.

Introduction:  In earlier postings (Note 1)  we have discussed the current status of global warming  due to greenhouse gas (mainly carbon dioxide, CO2) accumulation.  Davis and coworkers (discussed here) have shown that even if installation of all new energy facilities worldwide that rely on fossil fuels were to abruptly stop right now, the continued emissions from existing facilities and machines would continue feeding new greenhouse gas into the atmosphere, leading to further global temperature rise.  In contrast to this limited hypothesis, Hoffert, in his commentary on the Davis article (presented here) , emphasizes the very dire situation that we will actually face in the future because of the accelerating addition of new CO2-emitting facilities.  Recent predictions of future global warming from the United Kingdom and the United Nations Intergovernmental Panel on Climate Change suggest that average global temperatures could rise 4 deg C (7 deg F) or more from today by the end of the century.  Such a drastic change in climate would lead to serious unfavorable effects on human populations around the world.

The CO2 Bathtub.  Suppose that the earth’s atmosphere is a bathtub, containing air with  CO2 at the present concentration of 390 parts per million (ppm; this means that out of 1 million molecules of all the gases in the atmosphere, 390 are CO2).  In this imaginary model, if the level of CO2 were to decrease the bathtub would be less full, and if the level of CO2 were to increase, it would ultimately overflow (see image below).  Thus, in this image, the bathtub represents the world’s CO2 level at the present time, and further represents the baseline for the additional CO2 accumulation anticipated by the climate scientists.  The CO2 bathtub at its present level also correlates with global warming (the planetary long-term average of measured temperatures) which is now about 0.7 deg C (1.3 deg F) above the average temperature that prevailed prior to the beginning of the industrial revolution, when the CO2 concentration was 280 ppm.

The Atmospheric CO2 Bathtub, showing pre-industrial (280) and current (390) CO2 levels.

Bathtubs are installed with faucets, delivering fresh water to the tub; and with drains that, when open, empty the contents of the bathtub.  In our imaginary bathtub, there is a “faucet”, made up of all the planetary processes that deliver new atmospheric CO2 into the bathtub.  There is also a “drain” that is partially “open”, such that some of the CO2 delivered into the atmospheric bathtub by the “faucet” is depleted.  In the previous posting we discussed the “virtuous cycle” of CO2 production and removal that was operating during the millennia before the onset of the industrial revolution.  This cycle operated with a dynamic equilibrium, maintaining the atmosphere, or in our present image, the bathtub, at the constant level of about 280 ppm CO2, or about 72% of its present level.  We will not consider the processes underlying this virtuous cycle any more here.  Rather, let’s mention the newer man-made processes that contribute to filling or emptying the bathtub. 

The Bathtub’s “Faucet”.  By far the largest contributor to the “faucet”, adding new atmospheric CO2, is the worldwide burning of fossil fuels for energy.  This energy provides mechanical motion in transportation vehicles of all kinds, including cars, trains and airplanes.  It is also used significantly in electrical appliances and apparatuses, and in heating and air conditioning of living and working spaces.  An additional contributor to the CO2 “faucet” is the large scale destruction of tropical forests, primarily by burning, to clear land for agricultural use or other purposes.  It’s important to note that this burning is on a scale that vastly exceeds the processes of dynamic CO2 equilibrium taking place in the primordial “virtuous” cycle.

The Bathtub’s “Drain”.  The major process “draining” atmospheric CO2 from our bathtub is the absorption, or dissolution, of atmospheric CO2 into the oceans of the planet.  A certain fraction of atmospheric CO2 dissolves into the oceans, but this process does not remove all the additional CO2 that we add by burning fossil fuels.  The absorption of CO2 into the waters of the oceans itself has detrimental environmental effects which will be discussed in future postings.   Another potential process that might contribute to “draining” atmospheric CO2 from the bathtub could be reforestation undertaken by humans.  This activity occurs in addition to the “virtuous” cycle of primordial times.  Its effect requires decades to become significant, however, since the planted trees have to grow to a size that would draw significant amounts CO2 out of the air.

The Current Level in the Bathtub.  At the present time, the “level” in our imaginary bathtub is not staying steady, but rather is rising in the tub.  The people of the world are burning so much fossil fuel that the level of atmospheric CO2 is rising by about 2 ppm per year, corresponding to about 0.5% per year, even though the “draining” processes remove part of the added gas.

The Future Level in the Bathtub.  As noted in the Introduction, Davis, Caldeira and Matthews, Science Vol. 329, pp. 1330-3, 2010; see Note 2 and see also http://warmgloblog.blogspot.com/2010/09/todays-co2-emitting-devices-add-to.html) have shown hypothetically that even if installation of all new energy facilities worldwide that rely on fossil fuels were to abruptly stop right now, the level of atmospheric CO2 in our imagined “bathtub” would continue to rise, in view of the continued emissions from existing facilities and apparatuses.  This would continue to lead to further global temperature rise for several decades.  Only as the presently installed base of fossil fuel facilities and apparatuses ages and is removed from service would these processes level off and the level in the “bathtub” begin to fall.

In reality, however, we know that new facilities that consume fossil fuels are constantly being added to the energy economy. The United Kingdom National Weather Service (Met Office) reported in 2009 that CO2 emissions are proceeding at a higher rate than was thought only a few years earlier.  In other words, not only is the current level in our “bathtub” increasing at about 0.5% per year, but the rate of rising of the level is most likely going to increase for the indefinite future.  Very briefly, this can be ascribed to increased demand for energy in developed countries of the world, and to the addition of vast new portions of the global population to the demand for energy-requiring apparatuses and living conditions, populations that earlier had minimal demands for energy.  Indeed, the Met Office predicts that the global average temperature could be 4 deg C (7 deg F) higher than today (note: 4.7 deg C higher than preindustrial revolution times) by 2100, using a “high-end emissions scenario”.  The level in our atmospheric “bathtub” is foreseen as rising continuously into the future, with no pattern currently in view that eases the increase, or the rate of increase, of the bathtub’s level.

We Must Level Off the Bathtub As Soon As Possible.  Our imagined bathtub shows clearly that the world’s peoples have to stop the level of atmospheric CO2 from rising any further as soon as possible, because each increase in the bathtub’s level correlates with additional global temperature rise.  This simple picture makes it very clear that it is not sufficient simply to slow the rate of burning fossil fuels, because all this will do is slow the rate of rising of the bathtub’s level.  What is really needed is to approach the situation imagined by Davis and coworkers, i.e., not building any new fossil fuel-burning facilities right away.  As described above, even this drastic requirement still results in having the level in our bathtub continue rising for several decades before leveling off.  In our model the bathtub is equipped with both a faucet and a drain.  The scenarios of Davis and coworkers, and of the Met Office, are concerned primarily with the faucet.  In fact, there is little technology currently available, other than reforestation, that has the effect of “opening” the drain more than it is now.  It is for this reason that global warming scientists stress the critical need for reducing the burning of fossil fuels to zero as soon as possible.

Note 1. http://warmgloblog.blogspot.com/2010/09/todays-co2-emitting-devices-add-to.html;

http://warmgloblog.blogspot.com/2010/10/we-need-to-achieve-alternativesustainab.html;    http://warmgloblog.blogspot.com/2010/10/why-we-need-massive-effort-for.html.

Note 2.  Abstract available online free, or the full article for a fee or through personal or institutional subscription.  Many public libraries, and university libraries open to the public, receive the journal.

Present Federal Expenditures for Greenhouse Gas Reduction Are Inadequate

Summary: Global warming based on greenhouse gas emissions arising from burning fossil fuels threatens critically to alter living conditions on our planet.  In the previous posting, the findings of climate scientists were presented, showing that a massive effort, of the size devoted to the moon landing program initiated by President Kennedy, in order to place the U. S. on the path to a carbon-free energy economy.  In Tom Friedman’s column for Oct. 13, 2010  he details that the U. S. is currently embarking on a small number of projects budgeted in the $20 million dollar range.  It is clear that, given the urgency of dealing with global warming, a far greater effort by the government and private enterprise is called for.

Introduction:  In earlier postings we have discussed the current status of global warming due to greenhouse gas accumulation.  Davis and coworkers (discussed here) have shown that even if installation of all new energy facilities worldwide that rely on fossil fuels were to abruptly stop right now, the continued emissions from existing facilities and items would continue feeding new greenhouse gas (mainly carbon dioxide, CO2)  into the atmosphere, and continue to lead to further global temperature rise.  In contrast to this limited hypothesis, Hoffert, in his commentary on the Davis article (presented here) , emphasizes the very dire situation that we will actually face in the future because of the accelerating addition of new CO2-emitting facilities.  Recent predictions of future global warming from the United Kingdom and the United Nations Intergovernmental Panel on Climate Change (IPCC) suggest that average global temperatures could rise 4 deg C (7 deg F) or more from today by the end of the century.  Such a drastic change in climate would lead to serious unfavorable effects on human populations around the world.

Mini-Manhattan Projects.  In Tom Friedman’s most recent op-ed column of Oct. 13, 2010, he describes programs set up by U. S. Secretary of Energy Steven Chu and others in President Obama’s administration responsible for energy policy.  They identified eight areas to pursue:

1.      smart grid,

2.      solar electricity,

3.      carbon capture and storage,

4.      extreme materials,

5.      batteries and energy storage,

6.      energy efficient buildings,

7.      nuclear energy, and

8.      fuels from sunlight,

and termed these “mini-Manhattan projects”.  (The Manhattan project was the intensive and massive secret program to develop the atomic bomb during World War II.)  Although each was intended for low level funding for five years, according to Mr. Friedman, only items 6-8 have received appropriated funds, “less than $22 million”, for only one year.  They are located at academic or research institutions around the U. S.  (At the end of the Bush administration, the Department of Energy promulgated the report “Strategies for the Commercialization and Deployment of Greenhouse Gas Intensity-Reducing Technologies and Practices”.  It provides a detailed technical and economic analysis of strategies to mitigate greenhouse gas emissions.)

Mr. Friedman recounts that in describing this program to Kishore Mahbubani, the dean of the Lee Kuan Yew School of Public Policy at the National University of Singapore, Mr. Mahbubani was sure that “billions” of dollars, not millions, was the funding for this program.  Mr. Friedman had to emphasize "millions" to get the point home!  Singapore, an independent city-state, is reported to be well advanced in setting up a biomedical science center on a par to attract the best scientists in the world. 

Inadequate U. S. Funding for Energy R&D. There are several areas of concern about the present extent of federal commitment to reducing atmospheric greenhouse gas concentrations.  The U. S. Congress has not been able to pass legislation addressing global warming.  Although certain other regions of the world have put in place “cap-and-trade”, or emissions trading, policies to achieve this objective, the U. S. Congress has not acceded to this system since it was first proposed after the Kyoto Protocol of 1997.

Also on Oct. 13, 2010, the New York Times reported that a nascent commercial effort to produce solar panels in the U. S. has been undercut by a subsidized solar cell industry in China.

As an example of an infrastructure project intended to alleviate greenhouse gas emissions from private automobiles, Gov. Arnold Schwarzenegger of California is planning high speed rail lines in his state.  Unfortunately, in recognition of the fact that U. S. engineering capability is deemed inadequate for the task, he is considering to work with China for planning and construction of this project.

According to the New York Times energy blog, a large wind farm to be built in West Texas is to use parts manufactured in China.  The turbine engineering originates in Germany, and a gear box is designed by General Electric.  The project includes loan guarantees from the U. S. federal government.  The blog also refers to concerns expressed by Energy Secretary Steven Chu that the U. S. may be falling behind to China in developing alternative energy technology.

Conclusion:  For a variety of reasons, some which were discussed in a previous posting, there is significant skepticism or resistance in the U. S. to launching a major undertaking to supplant CO2-producing energy production with alternative or sustainable energy sources.  Some examples of this inadequacy were reviewed here.  Yet, the most recent assessment of global warming clearly shows that serious dangers will ensue if emission  of atmospheric CO2 is not eliminated.  The U. S. government should move to a sustained and intensified effort to develop and install technologies, and to promote commercial enterprises, that ultimately will eliminate CO2 emissions.

Why We Need A Massive Effort for Alternative Energy

Summary:  Previous postings (http://warmgloblog.blogspot.com/2010/09/todays-co2-emitting-devices-add-to.html; http://warmgloblog.blogspot.com/2010/10/we-need-to-achieve-alternativesustainab.html) discussed the current status of global warming arising from man-made greenhouse gas emissions arising from man-made greenhouse gas emissionsarising from man-made greenhouse gas emissionsarising from man-made greenhouse gas emissions.  Davis and coworkers have shown that even if installation of all new energy facilities worldwide that rely on fossil fuels were to abruptly stop right now, the continued emissions from existing facilities and items would continue feeding new greenhouse gas (mainly carbon dioxide, CO2) into the atmosphere, and continue to lead to further global temperature rise.  In contrast to this hypothesis, Hoffert, in his commentary on the Davis article, emphasizes the very dire situation that we will actually face in the future.  Recent predictions of future global warming from the United Kingdom and the United Nations suggest that average global temperatures could rise 4 deg C (7 deg F) or more from today by the end of the century.  Such a drastic change in climate would lead to serious unfavorable effects on human populations around the world.  Therefore massive governmental and private programs are needed to counter these trends and help stabilize the earth’s temperature.

Introduction: Before the industrial revolution, the atmospheric concentration of CO2 was relatively constant over the years, maintaining a “virtuous cycle” of CO2 production and removal.  Green plants undergoing photosynthesis convert atmospheric CO2 into cellulose, starches and soluble sugars.  On decay or as nutrients for animal life, this vegetation releases CO2 back into the atmosphere.  Animals, including humans, that feed on green plants or on other animals likewise metabolize their food for energy, thereby releasing CO2 as the end product.  Still further, humans burned surface vegetation for energy, also producing CO2, for cooking and heating.  These opposing processes went on in an endless cycle for eons, maintaining the atmospheric CO2 concentration relatively unchanged.  During this period the concentration of CO2 in the air remained at about 280 parts per million (ppm; molecules of CO2 per million molecules of all the gases present in air).

The industrial revolution broke the CO2 virtuous cycle.  Beginning in the mid 1800’s humanity began burning fossil fuels (coal, oil and natural gas) to provide additional useful work (the steam engine; the internal combustion engine) on a scale much larger than had been provided by the human body and domesticated animals.  Some anecdotal examples include railroads, factory mills, and electrical power generation.  This released new, unbalanced amounts of CO2 into the atmosphere.

Modern usage of fossil fuels.  In recent decades the use of these energy sources has expanded exponentially (i.e., increasing by multiples, rather than merely by addition).  Briefly, this is due to the following factors.  Our modern lifestyle favors extensive individual use of personal cars burning fossil fuels, with its underlying demand for highways to accommodate them.  There is a strong trend to live in larger homes that require more energy for heating and cooling.  Work spaces likewise have expanded greatly with still more needs for heating and cooling.  In developing countries, especially China and India, there is strong pressure for the populace, starting from minimal energy demands akin to the pre-industrial revolution period, to join the middle class with all the energy demands summarized above.  For example, China has been adding about two new coal-fired electricity plants a week for many years, since coal is abundantly available domestically (Library of Parliament of Canada, F. Beauregard-Tellier, 2007) .  In summary, on a world-wide scale, there has been profound expansion in energy demand, and fulfillment of that demand using fossil fuels. 

Increased CO2 will produce large increases in average global temperature.  This unprecedented growth in fossil fuel usage has caused a concomitant increase in atmospheric CO2 concentrations, which exceed the level that prevailed before the industrial revolution began.  Currently the CO2 concentration is about 390 ppm (Davis, Caldeira and Matthews, Science Vol. 329, pp. 1330-3, 2010; see Note 1), much higher than the level that prevailed prior to the industrial revolution; it is growing at about 2 ppm each year because of the expanded demand described above.  The present CO2 concentration has already led to increased global average temperature of about 0.9 deg C (1.6 deg F) over the temperature prevailing prior to the industrial revolution (Davis and coworkers). 

The United Kingdom National Weather Service (Met Office)  reported in 2009 that emissions are proceeding at a higher rate than was thought earlier.  It predicts that the global average temperature could be 4 deg C (7 deg F) higher than today (note: 4.7 deg C higher than preindustrial revolution times) by 2100, using a “high-end emissions scenario”.  Global climate patterns are such that polar regions and certain desert areas will warm more than others (see the graphic below).

Comparison of surface temperature projections from the high-end emissions scenario, without carbon cycle feedbacks. Temperature increases between 1961-1990 and 2090-2099, averaged over all high-end members. (United Kingdom National Weather Service).

The color coding in this graphic, superimposed on a map of the globe, is intended to show the extent of the increase in temperature in deg C above the baseline averaged over the 30 years from 1961-1990, that may be reached by the decade of 2090-2099.  The predicted temperature increases are shown starting with violet-purple shadings for predictions less than 1 deg C (1.8 deg F), up to strong reds and crimsons for predictions in the range 12-16 deg C (22-29 deg F).  The graphic shows that changes are greatest over the Arctic and northern temperate regions.  These results are in broad agreement with predictions made in 2007 by the Intergovernmental Panel on Climate Change (IPCC) , the United Nations consortium of thousands of climate scientists from around the world.

Negative effects of increased global temperatures.  Both the Met Office report and the IPCC analysis point out that higher average global temperatures of such magnitude will produce negative consequences for the wellbeing of humanity, including

Increases in high temperature extremes,

Increased extents of heavy rain and snow,

Melting of glaciers, snow and ice cover, and polar sea ice, leading to even more warming by direct absorption of sunlight, and to a significant rise in sea level, and

Decreased rainfall in regions closer to the equator such as Africa, Central America, the Mediterranean area and Australia.

A major reorientation of energy policy on a worldwide basis is called for.  The economic and social impacts of the predicted worldwide increases in the temperature of the climate are potentially severe in many regions of the world where large human populations live. In view of these effects, massive national and international projects are called for at the earliest possible date to minimize the effects of global warming, both already occurring and, more importantly, those predicted over the rest of this century.  Hoffert has characterized this as requiring a “Manhattan project”-like effort, referring to the massive U. S. program during World War II to develop the atomic bomb.  Another analogy might be the intensive U. S. space program to land men on the moon.  Only massive efforts on such scales, involving both governmental and private endeavors, can succeed in displacing all the fossil fuel-dependent installations world-wide with alternative technologies that fulfill our demand for energy without adding greenhouse gases to the atmosphere.

Note 1. Abstract available online free, or the full article for a fee or through personal or institutional subscription.  Many public libraries, and university libraries open to the public, receive the journal.

What’s Needed: An Alternative Energy “Moon Landing Project”

Note:  This posting discusses a commentary by Hoffert on the article by Davis and coworkers which was the subject of the posting immediately preceding this one.

Summary:  The world-wide transportation, space heating and electric generating installations currently in use will continue to produce new atmospheric CO2 emissions  (the main greenhouse gas) throughout their useful lifetimes, adding to global warming.  New installations yet to be built will produce even more CO2 emissions in the coming decades. 

In the previous posting, the analysis of Davis and coworkers is described.  They imagine that as of today we abruptly cease to manufacture new cars, planes, furnaces and air conditioning, and stop commissioning new electric power plants.  They show that even so existing facilities would add enough new atmospheric CO2 that the global mean temperature would likely rise by about another 0.6 deg C (1.1 deg F) from today’s level by 50 years from now.

Hoffert, in a commentary on the work of Davis and coworkers, emphasizes that the global warming threat is far more dire than this.  Even 5-10 year old estimates of CO2 emissions and consequent temperature rise are now recognized as seriously underestimating the actual global production by new CO2-producing facilities.  He concludes that major technological and political initiatives will be needed to restrict atmospheric CO2 levels to levels deemed acceptable in order to keep global warming within constrained limits over the next 50 years.

Introduction.  The world’s nations already have enormous numbers of cars, airplanes, power generating plants, and heating and cooling facilities installed throughout their economies.  Yet as a consequence of globalization and human aspiration, there is strong pressure to add large numbers of even more such facilities and items.  These new additions to global CO2-producing capacity constitute a critical danger exacerbating global warming.

Accounting only for existing installations, atmospheric CO2 will increase in the next 50 years.  In the September 10, 2010 issue of Science, Davis, Caldeira and Matthews (Vol. 329, p. 1330-3 ; see Note 1) report an analysis in which they imagine that no new CO2-generating facilities are added in the next 50 years. 

Their analysis predicts that the global concentration of atmospheric CO2 will increase from the present 390 parts per million (ppm; parts by volume of CO2 gas per million parts by volume of air total), to a predicted maximum of about 412 ppm at about 2037.  (A sense of how much CO2 is produced by burning one tankful of gasoline, or one thankful a week for a year, can be seen here.)  After 2037 the predicted CO2 concentration falls slightly to about 408 ppm by 2060.

Global temperature is predicted to rise from its present level in the next 50 years.  Davis and coworkers predict that as a result of this increased atmospheric CO2 the average global temperature will rise over the next 50 years, reaching 1.3 deg C (2.3 deg F) above the average preindustrial temperature by 2060.  This is higher than the current average global temperature of about 0.7 deg C (1.3 deg F) above the average preindustrial temperature.

Overall assessment of global warming.  In the same issue of Science independent commentary by Hoffert (Vol. 329, p. 1292-4; see Note 1) on the Davis article assesses just how difficult it will actually be to reduce CO2 emissions.  He cites the recent book by J. Hansen, a pioneer in climate research and an early proponent of reducing global CO2 emissions (Note 2), as representing a commonly agreed limit of 450 ppm for atmospheric CO2, which is expected to limit global temperatures to 2 deg C (3.6 deg F) above pre-industrial levels.  Hoffert concludes that significant world-wide efforts will have to be undertaken to achieve the limitations proposed by Hansen.  This is all the more so because estimates of future CO2 production and resulting global warming put forth five or more years ago are proving today to have been woefully inadequate, as explained below.

Past assessments of “Business As Usual” CO2 emissions are seriously deficient.  Hoffert cites an analysis by Pacala and Socolow from 2004 (Science, Vol 305, p. 968 (2004) (see Note 1), which builds on a baseline of projected emissions termed “Business as Usual” (BAU; see the graphic below).  In the left part of the graphic, up to year 2010, the red line shows actual production of worldwide CO2 emissions from burning fossil fuels.  In business as usual, it is supposed that future CO2 emissions continue as the straight red line




Adapted from Hoffert (Science). “Gt CO2” or “gtCO2” stands for gigatons of CO2, where 1 gigaton is 1 billion tons, and 1 ton is a metric ton, 1000 kg, or about 2200 lbs.  In the vertical scales on the left, please ignore the inner scale, and focus on the outer scale giving fossil fuel emissions in gtCO2/year. © American Association for the Advancement of Science.  Presentation of this Figure here is believed to comply with the "Fair Use" limitations (sections 107 and 108) of US Copyright law.

extension of the trend beginning at  2010, up to the year 2060.  As Hoffert points out, part of the BAU assumption relies on preserving the earlier advantage gained in the efficiency of energy production, with respect to CO2 emissions, by shifting from coal and oil (which require burning of relatively larger amounts of fuel) to natural gas (which produces more energy while emitting less CO2).  The BAU model adds a total of 175 Gt CO2 by the year 2060, shown in the graphic by the gray triangle.

However, since 2004, Hoffert points out that the above shift has halted.  This is especially so because the commissioning of large numbers of coal-fired power plants in China, India and the U. S has reversed the earlier efficiencies.  As a result recent CO2 emissions have been significantly higher than those assumed by Pacala and Socolow.  This is shown schematically in the graphic by the steeper turquoise line starting at 2010, and adding the total additional CO2 emissions by 2060 as the orange colored triangle, which is estimated to be worth about 450 Gt CO2.   Further, as a result of this worsening situation installing sustainable or alternative power generation, yet to be developed and placed in service, as proposed by Pacala and Socolow would not succeed to keep CO2 production below the 450 ppm limit proposed by Hansen.  Thus, as estimated by Hoffert, the current scenario (turquoise line) requires far more extensive installation of sustainable or alternative power sources than Pacala and Socolow proposed in 2004.

In stark contrast to these increasing CO2 scenarios, the “aging out” of fossil fuel technologies assessed by Davis and coworkers presented a trend of decreasing CO2 emissions (see the yellow line in the graphic).  Since this trend obviously will not occur, Hoffert evaluates the negative consequence of this failure as “175 more Gt CO2” in the graphic, coded by the orange line and the pale yellow triangle.  Adding up all these needs for compensating all the CO2 emissions by the year 2060 yields a total of 625 Gt CO2, the furthest right vertical arrow in the graphic.  The compensation must be derived from alternative or sustainable energy production that does not emit any atmospheric CO2.

Conclusion.  Many more power generating plants, automobiles, and home heating and cooling capabilities that produce CO2 are likely to be built over the next 50 years.  This is because many areas of the world are only now passing from “undeveloped” to “developing” status, and currently developing countries are adding to demand for these devices and installations as well.  These factors, and others, underlie the trend toward accelerating CO2 emissions shown by the turquoise line in the graphic above. 

It is imperative to undertake the worldwide installation of alternative and sustainable energy sources that do not release atmospheric CO2.  In Hoffert’s view this requires “programs with the scale and urgency of the Manhattan atom bomb project. One goal should be to develop technologies that can … eventually provide [the required] power by mid-century…from ‘clean coal’ and from nuclear and renewable technologies.”  The massive injection of federal support for the Manhattan Project, and for the program to land a man on the moon, effectively achieved their objectives.  Otherwise severe global consequences of excessive warming are predicted to occur.

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Note 1. Abstract available online free, or the full article for a fee or through personal or institutional subscription.  Many public libraries, and university libraries open to the public, receive the journal.

Note 2. J. Hansen, Storms of my Grandchildren, Bloomsbury, New York, 2009.