The first part of my argument is that there’s exactly one thing that can conceivably fix climate change (which, to be clear, I strongly believe is urgent). Well, if the threshold is “conceivably” then we could include things like carbon capture, but set that aside.  So the one thing we absolutely have to have is a carbon tax. And, ok, some people like cap-and-trade better, whatever. But what won’t work is imploring everyone to “do their part” and “think of the environment” when they’re drying their hands and such. Probably we’re on the same page so far. But how can I suggest that “doing your part” actually hurts?
It’s because the environmental impact of all socially conscious people limiting their carbon footprints is negligible. I know you hear a lot of statistics like “6.59 million trees would be saved if everyone stopped using paper cups” but it’s all specious. First, the entirety of the impact of consumers is small compared industrial sources of carbon. More to the point, you can’t hope to influence all consumers, only socially conscious ones. Even more to the point, the effort that that requires is out of all proportion to the impact on the environment it can possibly have.
Basically, we need to redirect all that energy to fighting for a carbon tax. Any effort directed toward individuals is misspent.
(What about buying carbon offsets? Yes! Those are great! For one they pave the way for a carbon tax. And in the very worst case they do no harm. More on that in a moment. The fundamental economic confusion that makes environmentalists decry carbon offsets — “rich people buying their way out of guilt!” — is super infuriating. Maybe that’s the milder form of my argument: A rich jetsetter with a parking lot full of cars but who conscientiously offsets every gram of carbon, really is part of the solution to climate change, not part of the problem.)
But my argument isn’t just that there are more effective ways to spend your environmentalist energy. Trying to limit your personal carbon footprint can, in the worst case, actually hurt. And I even believe it hurts in the average case. Because you’ll tend to impose constraints on yourself out of proportion to the social/environmental benefit. Even if, for the sake of argument, literally nothing but the environment mattered, your attempts to minimize your carbon footprint can easily backfire. Namely, by lessening your effectiveness at environmental activism. It affects your energy, your mobility, your income, your finite attention. It can even directly harm the environment, like if you drive further to go to a farmer’s market to buy local food. You have no idea how to make all the tradeoffs there. (And, again, any good you are doing is tiny, with literally no hope of fixing climate change.)
Which is the genius of a carbon tax (such taxes, more generally, are called Pigouvian taxes — they’re taxes that make the social/global cost of an item be reflected in the item’s price). With the right carbon tax, everyone — the socially apathetic, climate deniers, profit-maximizing companies — is necessarily making the right tradeoffs.
So, sure, anything you can do costlessly, like turning down the heat and wearing a sweater, go ahead and do that. But if it’s so much as slowing you down by making you pause to rub your hands together while emailing your representative about carbon taxes, it’s probably not worth it!
PS: There’s an important counterargument to all of this. Making those personal sacrifices shapes your identity and drives you to greater activism. (Not to mention making your activism and climate evangelism more persuasive.) So it may all be a virtuous cycle of greater impact, not like I described above with tradeoffs and compromises.
 I’m not opposed to high tech solutions on principle or anything, just that we don’t know if they will work. So we should pursue them orthogonally.