Last month I expressed personal alarm at the weather and the unexpected speed of change. Since then the global weather continues to break records, and I've thought of something slightly more constructive to say.

The asteroid which brushed passed the earth on Thursday was only identified as such the day before. Presumably our instruments calculated that it wasn't a risk and the alarm wasn't raised. But had the trajectory been six earth diameters to the side, how much notice would we have had to prepare ourselves for a 30 Hiroshima-bomb impact somewhere on the earth? What if the authorities decided not to tell anybody because there wasn't time to prepare and it would just cause unnecessary panic?

Sometimes climate change feels like that. We know time is running out, but governments are failing to tell the truth (for whatever reason) so we don't have the information or the political power to respond appropriately. No wonder people are waking up to the shortness of time and wondering how long they've got.

But the question in that form is poorly articulated perhaps because of the panic behind it. Who is we? What do we need time for? Do we really need to know? Might living in unknowing be wiser than planning for one specific possible future?

This post is an attempt to answer for myself. I want to avoid conflict and oppression in my own life and contribute to attempts to reduce harm. How long do I have for that?

It seems to me that no-one wants to be so irresponsible as to make a prediction too short. The shortest predictions are the most dangerous and potentially embarrassing, because they invoke the maximum panic and will be proven wrong the soonest. Mavericks like Guy McPhearson are marginalised and even belittled for advising us that "Only love remains".

At the more respectable end of the panic spectrum the UN is pushing countries to make 2050 commitments. But from the precautionary principle, it could be argued that that this date is even more irresponsible if it gives anyone the impression that we have wiggle-room.

So how long have we got? If someone would just give us a clue, we might make better decisions. If I knew an asteroid might hit my city 24 hours from now I might try to escape the impact zone, or seek or construct some kind of shelter; but if I had ten minutes I'd be lucky to get my children out of the building and underground. Less than that, and at least I could follow the advice of the Chinese/World government in the apocalypse action thriller The Wandering Earth to go back to my family and be with my loved ones.

Unfortunately climate change is not a Newtonian body in constant motion through predictable space, but a very large and complex system which eludes accurate modelling by computers. We don't know how long we've got or what event we dread. Every number you hear representing a target, threshhold or deadline, such as 12 years, 1.5 degrees, '2050 tipping point' is chosen by public relations advisors as a strategic target for policy makers and should be taken with a large pinch of salt. The body which has promoted most of those numbers has failed us badly by implying those things were knowable, and then placing them far too far in the future. But even if the models were accurate it wouldn't help very much because our well being depends in large part not on the weather but on society, another complex system which is premised on the first. That's not including the economy, another system which nobody understands, and which is designed to fail suddenly, unexpectedly and catastrophically.

The future most of us should be concerned about is not death in a heatwave or hurricane, or drowning in a rising tide, but social and political failure in a civilisation unable to adapt to changes in its environment.

So how long have we got - until what? I'm concerned that there's too much vague fearmongering and not enough thinking about how our society is most likely to fail. It probably won't be a distinct 'event' as its known in prepper-speak, a jump from capitalism to cannibalism, but could unfold in different ways and lead to different outcomes, some more preferable than others. Fiction can help us imagine possible futures like the charred landscape and fearful encounters of the The Road or living in a sealed dome of Logan's Run. The best prediction we can hope to make is to project forwards from now in a straight line, and for me Children of Men is the movie that does that best. Notice the police and the public, the dirt and decay, the slim hopes!

The continuing shocking weather will lead to poor harvests this year and probably poorer next year. Kudos to AllFed for their work on food security already. Around that time, maybe the year after, global food markets will go crazy as the rich countries begin hoarding food in earnest. It won't be the shortage itself so much as the political handling of it which will be brutal. Even now many humans are already starving for political reasons while food rots in vast warehouses. Lloyds of London predicted that Africa would be hit hardest and soonest. Maybe we could feed ourselves for a few years, but without improved yields it wouldn't be long before we saw food rationing in developed countries and governments using emergency rhetoric, political repression and of course debt-slavery to maintain order.

This at least seems like the harsh direction of the capitalist road we are on. The self-entitled, super-wealthy business and political classes will requisition everything to sustain themselves in militarised island ecovillages.

They would manage the rationing system while infrastructure decayed and schools and hospitals services failed and closed. Growing numbers of unemployed destitutes would be left to fend for themselves, dying younger than their parents from poverty related causes, including disease and violence.

So if I told you how long you had, would you wait until the last minute? One thing is for sure that you don't want to get caught in the rush for the exit. Once everyone else starts to panic, considered, conscientious action becomes much harder.

In his Deep Adaptation paper Jem Bendell put his neck out and guessed we had 10 years before 'societal collapse'. After a year of reflecting on this and of reading alarming science, I'm currently guessing that widespread food panics will come to dominate international politics in the next 2-4 years. The introduction of rationing will herald the crumbling of our political and financial freedoms.

So in my mind as a Western European, that 2-4 years is my window to do whatever I think necessary, desirable or possible with relative freedom. After that I think life will become harder, and choices narrower.

We can not now prevent a massive die-off of all that sustains us, starting with the insects now, expanding to the fish, trees, and surely also the grasses we depend on for food. However bleak the outlook seems - it could be worse. Maybe we'll go extinct and maybe we won't; wise choices could make the difference between the two. It is still possible to reduce the coming anguish and suffering; to reduce the mess and leave opportunities for the cockroaches to thrive after us; to face the future with dignity and open eyes.

I think many of should be looking at quitting our jobs in the commercial machine, preferably with a spectacular act of nonviolent industrial sabotage, cashing in our pensions and investing in real things we care about, whether it be survival, justice, personal or collective redemption, or just pleasure.

I believe there may still be important political/collective options which would both lessen the suffering and increase our survival odds. Neither of those things seem to matter to many people I talk to, but Extinction Rebellion is closest to my way of thinking right now. To me the wonder of the universe is enough to make me want more of it, so I expect I'll be working on system change as long as there is a system to change - not only with the hope to make things less bad, but because that is what I do.