Anecdote: About 20 years ago, when building the Linux kernel and gcc + libc still took overnight on a typical machine (which at the time was a Pentium with one IDE disk), a colleague performed a Linux compile on a Cray. It went so fast, he initially thought that he had turned a "pretend only" mode. No, within O(minutes), the machine had recompiled everything. And then Sequent and Convex mini-supercomputers showed up in significant numbers, and builds were never the same.
As to the picture of Greta: Today there are literally tens or hundreds of millions of computers involved in distributing images, facts and videos of and about Greta. The CO2 footprint of millions of people watching a video of her giving a speech in Davos is very large, and completely dwarves the footprint of crossing the ocean on a sailboat. We can now argue whether that's a good or a bad thing, but I'd rather not argue that, since it will get emotional.