Turn off your servers
TL;DR Turn off your servers. Use the scream test. Address fears. Proceed to lightswitch ops.
One easy way to reduce your CO2 emissions (and save some money) is to turn off your servers! Probably not all of them and not forever but there are certainly machines that are not fully utilized. You certainly know about one or two servers standing around that no one has used in months, or machines that are used only during business hours.