This is complex and will vary significantly by person. But for anyone the answer is almost certainly non-zero. Even if only marginally. And the trend seems to be increasing.
The second part of your comment, seems to assume only one kind of action is possible. Others might say, great let's do both.
I cannot respond to throwawayboise directly because of thread limitations.
On its face, this argument is clearly wrong. "Absolutely nothing", is not equivalent to extremely little. Especially when, as in the case of Google Maps, there is a large multiplier.
Elections are a different beast. Assuming first-past-the-post system where impact is only at the margin (50.0001%).
Whereas direct action on CO2 production is incremental. We can argue it's not enough, but we cannot argue it is literally nothing.
> On its face, this argument is clearly wrong. "Absolutely nothing", is not equivalent to extremely little. Especially when, as in the case of Google Maps, there is a large multiplier.
It makes sense to look at these things normalised per-capita.
So for Google, making a small change has a big impact per-Googler, but it's still a small change per-capita.
Making a small per-capita change is still a small change overall.
Though we might agree on the first premise below, there is an error in subsequent logical consequences:
"small changes alone are not enough" -> "only big changes can work" -> "small change X ought not to be undertaken"
To me parts of this looks like the fallacy of the excluded middle. To claim that X has some merit is not to claim that X on its own has sufficient merit. I apologise if you are not making such an argument, but throwawayboise and arsome certainly seem to have been. And such arguments are far from uncommon.
I do see your point about scale and multipliers but I believe efforts like these are important not only for their admittedly small yet not negligible impact, but also to help establish a foundation for the next steps that should be taken.
In the eighties, the cost-effectiveness of wind-power was way off the charts. However, you'd quantify it. Per turbine, per $, per power consumer. Turbines were just small and inefficient with few deployments. Now, many incremental improvements later, the same technology is in the right ballpark. It's a good thing those pioneers like Vestas didn't just give up when the absolute impact seemed far too small.
> "small changes alone are not enough" -> "only big changes can work" -> "small change X ought not to be undertaken"
I agree that this is wrong.
To make small changes do a lot, you have to have a lot of them.
You can still judge small changes by how much bang they provide for the buck. (Or more formally, employ the standard marginalist framework of economics.) A small impact is fine, if the cost was small, too.
Wind-power (and other renewables) are a bit complicated too judge on these historic efficiency measures, because there was so much government interference.
(I think government should perhaps tax CO2 and other emissions, but not offer any subsidies. I want eg turning the lights on less be on the same footing as switching to 'green' energy suppliers.)
(I also don't think the government subsidies for wind and photovoltaic actually helped that much in the long run. Eg as you can see, once the subsidies ran out, the photovoltaic industry mostly left Germany for China.)
There is absolutely nothing I can do individually that will have any impact whatsoever on CO2 levels or the climate. Nothing. One person's activity is simply too small a contributor. By the same token, whether I vote or not, or who I vote for, is also irrelevant in the outcome of elections.
The second part of your comment, seems to assume only one kind of action is possible. Others might say, great let's do both.