As a result, the nation-state and its subsidiaries, the typical loci for internalizing externalities, are limited in their remedial capacity. (However, since the United States contributes about 25% of the world’s CO2 emissions, its own policy could make a large difference.)
其次，它所带来的外部影响是真正全球范围的，因为温室气体可以在几天内就传播到整个世界。其结果是，国家和它们的属地，这些将外部影响国际化的典型所在地，在修复能力上却极其有限。（不过，因为美国占全世界二氧化碳排放量的25%，所以它的政策可以带来很大的不同。）