If you want to make infrastructure sustainable, you need to be very careful what words you use. That's what Hunter Vaughan and Nicole Starosielski found, through their involvement in a project to make subsea cables sustainable. Words like "sustainability" and "climate neutral" can mean different things, depending on who is talking. And if what you say is vague, then your efforts to be sustainable can get misdirected, or diverted into greenwash, or simply end up (like the words) meaningless.  Hunter Vaughan of the University of Cambridge and Nicole Starosielski of the University of California, Berkeley are part of the Sustainable Subsea Network. They are also co-authors of a paper called ICT Environmentalism and the Sustainability Game, which looks at how players like Greenpeace used language to build pressure for green infrastructure. They spoke to DCD about both: how we communicate about sustainability, and how sustainable our communications systems are.