You may have read that there are just eight, or 10, or 12 years to save the world from the climate crisis. There are not. It is already here, gaining strength every day as carbon emissions pour into the atmosphere. It is a slow-motion disaster. Action to avert the worst should have started last week, last year, last decade.

This is not a message of despair, though, but one of measured hope. The gap between the action we could take to reduce global heating and the action we are actually taking can be measured by a brutally simple metric: human suffering. That means every action that closes that gap, however small, is meaningful.

Deadlines focus efforts. They convert temperature rises and atmospheric carbon budgets into a value we understand: time

Deadly floods, hurricanes, heatwaves and bushfires are already taking lives and ruining livelihoods, and large and rapid cuts in carbon emissions are needed to prevent the damage from becoming far greater. But there is no deadline after which the planet explodes, no point at which action becomes pointless.

The idea of a deadline for saving civilisation stems from a 2018 report by the Intergovernmental Panel on Climate Change, a collaboration of the world’s top scientists. It found that cutting emissions by about 45% by 2030 would give a reasonable chance of keeping global heating below 1.5C, the target agreed on by UN nations in Paris in 2015.

But the scientists who wrote the report have said it is wrong to interpret that as a 12-year deadline, with some suggesting a Guardian headline at the time is partly to blame. Other media, such as the Washington Post, used similar framing, and the 12-year deadline has been cited by people as disparate as UN secretary general António Guterres, Prince Charles and Jeremy Corbyn. With a problem to solve, setting a timeline feels necessary.

But Greta Thunberg, with characteristic clarity, recently spelled out the mistake: “It’s never too late to do as much as we can, every fraction of a degree matters,” she says. “There are of course no magical dates for saving the world.”

Fundamentally, fighting the climate crisis is about fighting the injustice that it magnifies. Preventing the poor, who played no part in fuelling the climate fire, from getting burned. Enabling those with little wealth to build dignified lives without the use of coal, oil and gas. Creating a better world, where we stop exploiting the planet as if its resources were infinite and, through cooperation, learn to live within our means.

As Prof Myles Allen of the University of Oxford has pointed out, slavery was once a highly profitable provider of energy and we brought it to an end because it was an affront to the values that make us human.

All very noble, you might be thinking. But what about the cost of action? The answer is that the cost of inaction is far greater. The Paris agreement already passes the cost-benefit test and, in any case, there is no economic growth on a destructive, hothouse Earth – as the financial sector is beginning to recognise.

Taken together, the justice and economic arguments make it imperative that every decision taken every day by governments, businesses and communities must pass the climate test: will it cut emissions? From power plants to buildings, transport to farming, projects commissioned today will be running well beyond 2030.

Tackling the climate emergency means tough decisions today, not promises for tomorrow. In the UK, one imminent test is whether the government’s long-delayed £100bn national infrastructure plan, which includes many green initiatives, survives the coronavirus outbreak.

Deadlines can focus efforts. In the case of the climate emergency, they convert targets for surface temperature rises and atmospheric carbon budgets into a value everyone understands: time.

So here’s one: 19 November 2020. That is when the UN climate change conference, hosted by Boris Johnson and the UK government, is due to end. Unless nations dramatically increase their pledges to cut emissions, we will remain on track for a terrifying 3-4C of heating.

Every effort must be made to achieve success. But even if this deadline is missed, it will not be too late, because every act reduces human suffering. As Prof Mick Hulme, at the University of Cambridge, says: “History does not end, the future is not preordained and it is never too late to do the right thing.”

• Damian Carrington is the Guardian’s environment editor