摘要：The global warming intensities of crop-based biofuels and fossil fuels differ not only in
amount but also in their discharge patterns over time. Early discharges, for example, from
market-mediated land use change, will have created more global warming by any
time in the future than later discharges, owing to the slow decay of atmospheric
CO2.
A spreadsheet model of this process, BTIME, captures this important time pattern effect using the
Bern CO2 decay model to allow fuels to be compared for policy decisions on the basis of their real
warming effects with a variety of user-supplied parameter values. The model also allows
economic discounting of climate effects extended far into the future. Compared to approaches
that simply sum greenhouse gas emissions over time, recognizing the physics of atmospheric
CO2 decay significantly increases the deficit relative to fossil fuel of any biofuel causing land use
change.
