He believes that, because this method compares alternative means for achieving given goals, including safety and environmental concerns, CEA is a better method of analysis. His example makes the issue clear. Likewise, no matter how high gasoline prices get, for example, paying large sums can't produce more oil when we run out. After considering all of these things, I believe that CBA does fall short of environmental concerns. Economics is a science of supply and demand without moral obligations, presupposing that material gain is always good.
Ethics is strictly a way of addressing things from a moral perspective.
Thus, when it comes to the environment, the two clash. Environmental ethics say that gain is not always good, especially when the external costs are high. Slavery, for example, was very economically wise. Plantation owners were quite wealthy and production was going well. Ethically, however, there were more than a few problems.