A favourite sport of the anti-green lobby is hunting out the climate hypocrites. It’s Emma Thompson’s lifestyle that has most recently been the subject of frenzied scrutiny after the actress addressed the Extinction Rebellion protest in London a few weeks ago. “Emma Thompson the first-class hypocrite!” blared one tabloid headline last month after she was spotted dining on beef carpaccio while flying first class to New York.

So before I say any more about the lifestyle changes required to avoid catastrophic climate change, I’m going to hold my hands up. I’m a climate hypocrite. I care about the climate emergency. When I decided I couldn’t support Labour in the European elections, because of its Brexit position, I voted Green instead. But I’m ashamed to say I’m not great at applying my ballot-box behaviour to other areas of my life. The last time I ate red meat was last night. I’m heading to Gatwick to catch a flight after writing this.

There are those admirable saints who really do practise what they preach, but I’d bet most of those who profess to care about the planet are just as hypocritical as me. I don’t think it makes us bad people, just typically, fallibly human, lacking the willpower to do the stuff we know we ought, such as shedding a few pounds or putting away more in our pension.

I know we’re fast approaching a catastrophic climate tipping point, and yet I’m just not very good at forgoing a steak

In the UK, we’ve already done the (relatively) painless stuff – closing coal power stations – when it comes to reducing emissions. The next frontier is stuff that is either expensive – ditching gas boilers and switching to electric cars – or requires us to change the way we live. That will certainly involve eating less meat, the production of which accounts for 15% of global greenhouse gas emissions, more than all the world’s cars, ships, trains and planes put together. Beef is by far the worst culprit: one study recommended cutting global consumption by 90%.

It’s naive to think that we can achieve these sorts of lifestyle shifts by imploring people to do more. I already know we’re fast approaching a catastrophic climate tipping point and yet I’m just not very good at forgoing a steak, particularly when I know plenty of others won’t be either. The power of nudge is also limited here: shoving the steak further down the menu isn’t going to make me less likely to order it. So public policy inevitably ends up with sin taxes as the go-to policy lever for trying to get us to switch away from the bad stuff.

Sure enough, a meat tax has been mooted. But the big problem with green taxes is that they hit the least affluent hardest. It’s people on low incomes who are most sensitive to marginal increases in the cost of their food and flights and who might decide they can’t afford their one holiday a year as a result. But it’s the very well-off who can much more easily absorb the cost of green taxes who do the bulk of the polluting: the richest 10% of households in the UK produce four times as many emissions as those in the bottom 50. That’s one reason why a jury set up by the Food Ethics Council rejected the idea of a meat tax last week.

But, perhaps counterintuitively, I think the inevitable rise of the climate hypocrite – as awareness grows of just how much destruction we are set to wreak on the planet, but people still can’t quite bring themselves to pass up a Sunday roast or the holiday at the end of that budget flight – is a cause for optimism. I want to do more, but I know I need someone to force me to take my carbon footprint more seriously. And perhaps that means people will become more willing to countenance something more radical, but fairer, than sin taxes: saying there’s only a certain amount of meat or air miles we’re going to consume as a population every year and once it’s gone, it’s gone.

People could be allocated polluting credits to cover activities such as meat eating and flying that they can sell

Rationing is evocative of wartime Britain, when the amount of everything from petrol to sugar to eggs that each person was allowed to consume was tightly controlled. It commanded public support as part of the collective war effort. That support might be much harder to win when we’re not at war, but along with microbial resistance (a whole other disaster-movie plotline) the climate crisis is the biggest existential threat facing mankind. Maybe the Blitz spirit does have some contemporary relevance.

Rationing to tackle the climate crisis could be given a modern-day makeover. People could be allocated polluting credits to cover activities such as meat eating and flying that they can sell and buy in an online marketplace. If you’re short of cash, or not that bothered about eating meat or flying abroad, you can feel smug as you sell your credits to someone who is, which makes this far more equitable than green taxes. And setting a population-level limit on something such as meat consumption would create huge incentives for companies to invest more in the production of things such as environmentally friendly, lab-grown meat.

It’s not a new idea; in fact, in the mid 2000s, David Miliband waxed lyrical about personal carbon “credit cards” when he was environment secretary. But the government later distanced itself from the idea, coyly calling it an idea “ahead of its time”, to strident criticism from a group of cross-party MPs.

A decade on, it’s surely an idea whose time has come. The climate school strikes show the next generation is hungry for more radical action. Sure, the hypocrite-hunters will balk at the prospect of rationing to save the planet. But I’m optimistic that more of us will come to see that it’s going to take something more drastic than trying to persuade people to voluntarily scale back to whip us into shape.

• Sonia Sodha is chief leader writer at the Observer