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This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.

Each post will begin with a capsule summary. It will then proceed with captioned sections to amplify and justify the statements and conclusions of the summary. I'll present images and tables where helpful to develop a point, since "a picture is worth a thousand words".

Monday, October 4, 2010

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.
 

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