Ask HN: What can you do against climate change as a software engineer?

Nothing. Seriously, look at the graph of the temperature of the last 10,000 years and you will see that independant of humans, temperature was a couple of times significantly higher than today. Temperature will rise no matter what you do.

Avoid work with GPUs or creating things that get others to contribute to climate change. My thoughts are that software devs can have far more influence downstream than by individual actions.

Help scale PoW blockchains? Or code them out of existence?

Use dark mode on your laptop. And smaller size text wastes fewer pixels.