That's the big thing that pushed me to add LetsEncrypt to my blog. I was on some Belgium sim card and the ISP injected some crap via JavaScript at the top of my website. I couldn't even read it; didn't properly detect language/locale, but it looked like some warning about being near my data limit.

A proxy can't cache the ressources anymore. SSL overhead, CPU used by both parties to do the encryption. But the ISP can't alter the page.

TLS takes considerably more watts of power on the basis it actually does more work and shuffles more electrons around the CPU. I suppose that loosely converts into carbon footprint.

However even if it is an issue, most sites sending 6 meg of JavaScript crap down that gets recompiled on every visitor’s machine, autoplaying videos and advertising would be doing more damage. So if anyone is going to complain they should probably start there...

We should ask our governments to ban the use of https and just trust each other

(</ironic>, just in case some internet random folk thinks I’m serious)