2 ways:
Too many engineering firms now adays are getting lazy with the development "just because we have fast processors" IMO. This is how my brain thinks, so naturally it spreads throughout my life. And the reality is, as programmers, we have direct control over computer hardware, which is plugged into the wall. Out of the wall comes power and power is GENERATED AT COST at a power plant either using coal, wood, nuclear reactor, wind, water, etc....
This may sound silly, but it's completely true. When I analyze malware, often one of the ways (of many) I get suspicious something is bad during dynamic analysis is when I hear the fan rev up and the computer start to get warm. Why is a "notepad" application cranking all my CPU cores like that? With billions of devices plugged in, you bet that affects the environment.