Ad Net Zero is a significant response by the advertising industry to both the climate crisis and corporate movement to a decarbonization of the economy. As the advertising ecosystem is responsible for shaping demand and consumption behaviours, not only does the industry need to attend to its own carbon footprint (i.e. Advertising Emissions), but also the carbon consequence it enables more broadly on society (i.e. Advertised Emissions). However, appropriate measurement and management of these two components is challenging due to the compex nature of the industry. Here we present a consistent approach to estimate the impact of Advertising and Advertised Emissions, including measures of post-ad-exposure behavioural change, and a portfolio approach to manage the trade-offs across campaigns in commercial and carbon efficiency.