Last week I warned that Philip Hammond was right to be concerned about the idea of promising to fulfil far-off radical goals on climate change without actually explaining, debating or gaining popular consent for the vast up-front costs involved.

Avoiding such honesty is not only irresponsible and cynical – deceitful, even – it is unwise and risks a backlash by declaring something to be so important that campaigners believe they can justify bypassing the hard work of bothering to engage with the people about what it is they are proposing.

There are pretty clear headline numbers from YouGov and others for general questions on the theory of acting on the issue, particularly among the young. These findings are normally used to justify skipping the grubby question of the costs and practicalities entirely.

But yesterday, Sky Data published a poll which illustrates the problem with this rather well, and should give pause to anyone who thinks it is that easy:

That is a pretty stark demonstration of the issue. Yes, ask people “should we act” or “is it a priority” and they will say yes. But currently if you ask people where the money should come from to do so – tax, borrowing (which is, after all, just deferred tax), or lower spending elsewhere, then they reject all three.

And this isn’t a question of older voters rejecting action that they young want – with all the usual caveats about cross-cutting polls, Sky doesn’t find a majority of 18-34-year-olds supporting any of the three options, either. They are pretty much average on all three: 42-37 against tax rises, 50-22 against increasing borrowing, and 74-10 against cutting public services.

Either the proposal has to change, or those pushing for it have to actually come clean with the people who will foot the bill about how much it will cost to fulfil, and win their consent. Otherwise the debate will happen further down the line, which helps nobody.