Yes, they go very quiet when you ask them how they're doing their bit to solve this emergency they claim to believe in. Because they're not doing anything. Which leads us to ponder: do they actually really care about it, or are they just virtue signalling like well trained chimps?
I reckon they're virtue signalling. It is something that left wing types seem to do a lot I've noticed. They want others to believe they are good people, although they only end up fooling themselves most of the time.
For instance, on the topic of global boiling, they don't mind that China is opening a new coal power plant every week, whilst we've closed nearly all of ours. They won't criticise China; in some cases they will even praise China... Because they don't really care about the environment, despite spending hours and hours on end going on about it. The environment, amongst other topics, are really vehicles they use to disguise their sense of personal inadequacy, self loathing and spitefulness. In some cases, of course, we are just dealing with people who are mentally ill or who have sub-average IQs.
As is often the case, look past what they say - look at what they actually do.