The five stages of [insert apocalypse here]

The first stage was denial: it's not really happening, it will go away, it won't affect us.

The second stage was scientific rescue fantasies: brilliant research is being done on the problem, the solutions are just over the horizon, we'll be fine.

The third stage was cheerful inevitablism: there's nothing we can do about it and we'll just let it happen, the costs of trying to stop it are unacceptably high and they won't work anyway, let's just carry on and get through it.

But then it became clear that even the damage that was already being done was pretty intolerable and that it was only going to get worse; and that action that could stop it was possible - difficult, but possible.

So we entered stage four, voluntarism. We were urged to take action. Lots of individuals, organisations, local governments and so forth did. Our lives changed a lot. But not enough. Large parts of society and the economy carried on more or less as before, unwilling or unable to make the changes they needed to.

Hence stage five: where government imposes actions on everyone, and - therefore - also takes on itself the costs of those actions. Of course, still in the hope and expectation that the scientists who we last heard from in stage two will come up with solutions which will ease the problem in due course. But we can't afford to do nothing while we wait.

I'm talking, of course, about the global climate crisis.

I don't mean to be flippant. The analogy between climate and COVID-19 isn't a perfect one. The timescales are very different: climate change is too slow for our political cycles, and the novel coronavirus is if anything too fast. But I think the parallels are instructive. We try to avoid action until it becomes clear that we really can't.

Specifically: in the climate emergency, we are now at stage four. Lots of people, institutions and countries are doing lots of things; lots are not; and it is not yet nearly enough. It can feel as if we are stuck here and are fiddling with LED light bulbs while the planet burns.

So here's my word of encouragement based on the COVID-19 experience so far: stage four is vital. Only when there is a large enough critical mass of people and institutions acting on their own initiative does it become politically possible to move on to stage five. Each individual initiative doesn't just save those few grammes of carbon, it also nudges the political needle another fraction of a degree, turning what was once normal behaviour into something that's first old-fashioned, then deserving of disapproval, then shameful, then outrageous. And that's when things change.

And as with COVID-19: we will in due course find out whether they've changed fast enough, and how many people have died unnecessarily along the way.