the world will suffer significantly in the future due to global change in temperature, finding the correct social discount rate for the benefits of reducing CO2 emissions and other harmful greenhouse gases is very important. In 2005, a New York Times article written by Hal Varian states:The choice of an appropriate social time discount rate has long been debated. Some very intelligent people have argued that giving future generations less weight than the current generation is "ethically indefensible." Other equally intelligent people have argued that weighting generations equally leads to paradoxical and even nonsensical results. The range in the social discount rate for a cost–benefit analysis in this issue range from zero to over 3%. Some argue that the only reason for discriminating against future generations is that these generations might cease to exist in the future. Thus the rate of time preference should equal zero since the probability for such a catastrophic event is so low (assumed to be 0.1% per year). This infers that there is equal weight given to all generations. However, to the extent that future generations are likely to be richer than those in the present, a positive discount rate should be applied reflecting the diminishing marginal utility of consumption. The Stern Review on the Economics of Climate Change is one such report that argues for zero discrimination of future generations, but applied a range of positive discount rates to its assessment based on the range of consumption projections predicted by climate models at the time. There is an important distinction here between discounting, which is partly a function of expected future consumption paths, and pure time preference, which is the rate of discrimination through time. A common misconception is that the Stern Review applied a zero discount rate. In fact, the Stern review's stochastic projections applied many discount rates reflecting a range of consumption projections, all of them positive, even while it took the rate of time preference to be close to zero. This confusion is prevalent. William D. Nordhaus of Yale examines a model of climate change that is similar to the one used in the Stern Review but with a 3 percent social discount rate that slowly declines to 1 percent in 300 years rather than the 0.1 percent discount rate used in the Stern Review. In his model, the welfare of future generations is given less weight than the current generation's