A 'discount rate' for the consumption of future generations from curre
nt investments for their benefit is typically composed of two parts: '
time preference' and an allowance for the lower marginal utility of co
nsumption due to higher average levels of consumption in the future, T
ime preference would be involved if one were postponing one's own cons
umption; it has little or nothing to do with income redistribution, wh
ich is what greenhouse abatement is about, A lower marginal utility of
consumption is an anomaly in income redistribution: we rarely deliber
ately transfer consumption from the less to the more well-to-do, Time
may serve as a kind of measure of distance; we may prefer beneficiarie
s who are closer in time, in geographical distance, in culture, surely
in kinship, Perhaps to keep our thinking straight we should use a ter
m like 'depreciation', rather than 'discounting'.