The biggest factor is the massive cost and the tiny reward. Reducing emissions is the only response to climate change that environmental campaigners talk about, despite the fact that repeated attempts to do so – in Rio in 1992 and in Kyoto in 1997 – failed to make a dent in emission levels.
他们的理由是完全可以理解的。最大的因素是碳减排高昂的成本和微小的回报。尽管有几次这样做的努力——1992在里约热内卢和1997年在京都的努力——都没有在排放水平上取得进展的事实，减少排放仍然是环境保护主义者讨论的对气候变化的唯一应对方法。