The question of whether international trade rules apply to the global carbonmarket has been a source of continuing academic debate. One particular source of disagreement is the extent to which trade in carbon units (also known as emissions permits or emissions allowances) constitutes a “financial service” for the purposes of the WTO Agreement’s Annex on Financial Services. This Article re-evaluates that debate in light of a number of key recent developments: the first everWTO dispute involving the Annex on Financial Services and shedding light on its scope and coverage; the designation of carbon units as “financial products” under the municipal law of a number of important jurisdictions; and the rapid proliferation of emissions trading schemes. These developments make clear that carbon markets are indeed subject to international trade rules, which could immediately impugn a number of emissions trading schemes that discriminate between carbon units based on their jurisdiction of origin.