Computational and storage tasks can nowadays be offloaded among data centers, in order to optimize costs and or performance. We set out to investigate what are the environmental effects, namely the total CO2 emission, of such offloading. We built models for the various components present in these offloading scenarios, and we incorporated these models into an online calculator available to users. Our online calculator determines the total CO2 emitted by performing computational or storage tasks at a local or remote data center, provided that the energy sources of the data centers and the network connecting them are known. The demonstration we propose will allow conference visitors to use our website/calculator to get a sense for the impact of offloading their storage and computational tasks.