Only Europe has tried to make a serious shift away from carbon emissions, creating a system that requires each industrial emitter to obtain a permit for each ton of CO2 emissions. Because these permits trade at a market price, companies have an incentive to reduce their emissions, thereby requiring them to buy fewer permits or enabling them to sell excess permits for a profit.
只有欧洲认真尝试减少碳排放，并建立起要求工业排放企业取得吨二氧化碳排放许可证的全套管理制度。因为允许许可证上市交易，企业才有动力降低排放，并借此减少许可证购买量或将多余份额卖出获利。