Bridging the Carbon Gap: Fossil Fuel Use for the 21st Century
Coal gasification as a transition plan to build lead time to develop sustainable, climate-friendly energy technologies.
Editor's Note Several of the sources for this article and accompanying sidebars are referenced numerous times. While the note numbers are roughly sequential, they may occasionally appear out of order because an earlier source is again referred to-with its original number.
In past writings I have questioned the overly alarmist projections of some experts concerning the impact on global climate resulting from the emission of so-called "greenhouse gases" due to human activities. Such greenhouse gases include carbon dioxide, methane, nitric oxide, and halogenated carbon compounds, but for our purposes CO 2 remains the key concern. 1, 2, 3, 4
I still challenge those dubious projections. Yet I also believe it would be prudent to limit emissions of greenhouse gases from human activities-that is, to limit emissions to levels that the more objective climatologists consider as acceptable. Such levels are higher, perhaps, than some would favor. However, I contend that this "middle way" would restrain global warming to manageable levels, improving on "business-as-usual," and thus allow for the necessary lead time to bridge the "Carbon Gap"-the century-long transition to commercially sustainable and climate-friendly energy technologies, by year 2100.
At the very least, there is danger in maintaining the status quo for carbon emissions. Over the past several hundred years, anthropogenic CO 2 emissions have increased from pre-industrial times, when atmospheric CO 2 concentrations were about 280 parts per million by volume (ppmv). The level reached 367 ppmv in 2000. And such concentrations conceivably could rise as high as 900 ppmv by 2100, under some highly unlikely business-as-usual scenarios. 5 This path would imply cumulative anthropogenic carbon emissions of roughly 2,200 billion metric tons (gigatonnes) between 1991 and 2100. 6, 7
Even the most confirmed contrarians of theories of human-induced climate change would agree that this scenario would be too risky. 8
Of course, the plan I propose to moderate carbon emissions still would entail a continued, transitional reliance on fossil fuels. It would produce a significant further increase in atmospheric concentrations of CO 2 over the next century-to about 550 ppmv by 2100. It would imply cumulative anthropogenic emissions of about 1,000 gigatonnes of carbon (GtC) over the period from 1991-2100, and lead to a doubling of the pre-industrial level of atmospheric CO 2. A substantial number of climatologists now believe that this doubling would be acceptable, however, though it would carry certain implications for global climate.
Others, such as Dr. Robert H. Williams, at Princeton Environmental Institute, would prefer a more stringent ceiling of 450 ppmv for atmospheric concentrations of CO 2. This tighter limit would imply anthropogenic carbon emissions of 650 gigatonnes on a cumulative basis during the period from 1991 to 2100, when it would be expected that new energy technologies would take over.
This strict limit favored by Williams and others would likely result in further increases of no more than 2° C (3.6° F) in average global surface temperature.
Yet I tend to side with the climatologists that support the