Yeah... The "1GB of data transfer --> 3kg of CO2" is high by orders of magnitude. Computer systems and network equipment have a fixed install and fixed operat

Yeah... The "1GB of data transfer --> 3kg of CO2" is high by orders of magnitude. Computer systems and network equipment have a fixed install and fixed operational costs. I think the incremental energy cost of transferring 1GB across 5000km is on the order of 1000 Joules of energy. I think 10Gb optical transfer requires less than 10W per 100km... this probably a really high upper limit (equipment electrical power plus cooling power). 1000 J is roughly equal to 0.0003 kWh 1 kWh electrical power generation produces about 200-500g CO2 depending upon the electrical grid. So that would work out to about 0.15grams per 1GB of data, at the most. The fixed upfront equipment costs and carbon footprint do need to the factored in as well but they are not going to amount to much. So yeah... we talking about less than a gram of CO2 per 1GB. I don't care to run the numbers further than this...