Which is what Tony has said. If we in the UK stop fossil fuels tommorow the global change will be non measurable, but everything comes to a halt including windturbines which use oil for there gearboxes. We basically create our own extinction event, there will be nothing because transport stops, energy stops, communications stop and we have no heating, lighting or cooking facilities.
You can't just do nothing and expect China and the US to do it all. Because even if they totally sorted themselves out, there's still an awful lot of emissions not including them. What level of relative scale do you want to put it at? If you go with emissions per capita, the UK is relatively heavy in proportion to half of the world, but mid-table compared to the whole world. If you go with UK as a national unit total emissions relative to the rest of the entire planet for total emissions, it's pretty insignificant. If you compare UK to Australia by capita, we're saints. If you compare Europe as a whole either per capita or by total emissions, including the UK or not, it's fairly horrendous.
But the EU (and in that I'll include the UK) has its lowest emissions in 58 years, says google. Reduced by 7.6% in 2023 it says. Now I bet some EU countries didn't reduce their emissions at all, but some did. Did they waste their time? How much better would it have been if all of the ones who didn't reduce had managed to do it as well?
It's a crappy argument. And if you say "but the UK isn't in the EU, so what's the point?" then you are just attempting mental gymnastics to swerve the point.
Of course, if we're all drinking from the same lake and one person pours a large amount of anthrax in it then we're all going to die (ehhehehehahaheheh), but that doesn't mean we can all just chuck in anthrax as well. What you need to do is not throw in anthrax and stop the bastids who are from doing it.
I did a full time Environmental Science degree in the late noughties, when hockey stick graphs were all the rage, at a uni that specialises in climate science. I didn't focus on climate myself but I had modules and it invariably came into everything I did there, of course. I didn't do any of it for a career and it was a long time ago and I forget, so none of this makes me an expert on it. But the reason I am telling you this is that I have argued this stuff for many years and the amount of astonishing b*llsh*t that people come out with on this is myriad. I have heard it all.
The "we won't change anything if nobody else does" is incredibly common, is even demonstrably true, but is never, ever followed up by any intelligent thoughts after. It's just an excuse to continue to be selfish and lazy and makes no logical sense. All nations are islands, but form one world. If I have to pursue that train of thought any more to make my point, you're just being obtuse.