Estimating the changing environmental impacts of ICT-based tasks: A top-down approach

We develop a simple method for attributing the environmental impacts of tasks performed on ICT devices according to the amount of time spent by the user pursuing them and the amount of network bandwidth they require. We use broad categories of tasks and ensure that the total impacts of all tasks add to 100%. Using publicly available data, we develop a case study of energy consumption in the U.S. and demonstrate that by 2015 web-based video will become a dominant driver of ICT energy consumption, due to its very high bandwidth requirements. Our approach is useful for the identification of broad trends in the aggregate behavior of the entire user-base.