托尔还质疑，使用历史价格数据作为基准来预测2020年以后的事情，这是否合理呢？
Tol also questions whether it is reasonable to use historical prices as a basis for projecting beyond 2020.
铁矿石价格或将下滑，但今年基准价格的走低是2002年以来的首次。
The price of iron ore may be falling, but this year's drop in benchmark prices is the first since 2002.
作为基准合约的2010年12月欧盟排放配额价格上周四每吨二氧化碳跌了0.7欧元，收于13.66欧元。
Eu Allowances for December 2010, The benchmark contract fell 70 cents per tonne of CO2 Thursday, settling at 13.66 euros.
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