The Australian economist John Quiggin has an illuminating discussion on his website ( http://johnquiggin.com ) that comes down on the side of a $0.50/gallon tax, because he projects that spending today to reduce carbon emissions is a good investment for the future. Assuming that annual per capita income grows at about 2% per year worldwide, a marginal expenditure of roughly $70 today to cut carbon emissions would be worth it if, accounting for damage from global warming and adjustment costs, the world of 2100 would be $500 richer in year-2006 purchasing power.
澳大利亚经济学家John Quiggin在他的网站上 （http://johnquiggin.com ）有一段令人耳目一新的探讨，其结论是将税额定为每加仑0.5美金，因为他预测今天在减少碳排放方面的支出是着眼未来的一笔好的投资。假设全球人均收入年增长率为2%，如果以2006年的购买力计算，2100年的世界比现在要富500美金，那么我们今天的一笔用于减少碳排放的约70美金的支出就非常明智。