During the last decade, it has become widely accepted that global warming is not simply a natural cycle but that it is being exacerbated by human activity and that the impact of emissions from man-made technologies is substantial and critical. Reduction in the release of greenhouse gasses is therefore very urgent. Rather than direct regulatory action, governments around the world have been convinced to harness the power of markets to the problem. Emission trading schemes (ETS) have been the result, although the process is popularly referred to as 'carbon trading'. This paper considers carbon trading from the perspective of the eCommerce researcher and practitioner. It discusses the nature of the tradable items, and the possible forms of marketspace mechanism in which trading may occur. Both the theory and practice of eCommerce suggest that considerable care will be needed if ETS are to achieve the intended reduction in the global warming effects of industrial technologies.