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
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
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
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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,