Here we go. A nip in the air, the Christmas lights are up, Black Friday deals are still hanging around, and it is time once again for another international climate conference.

The COP, or conference of the parties to give it its full name (the “parties” being the signatories to the UN Framework Convention on Climate Change) is the UN’s annual climate talks. This year it’s in Madrid, next year it’s Glasgow’s turn. They’ve been going since 1995 and although they are covered by journalists, they tend to run pretty inconspicuously.

But this time it feels that things might be different. That this is a special COP. Why not, when we’ve had the climate strikes, parliament calling a climate emergency and the advocacy of the inspirational Greta Thunberg? The world might finally be watching.

Except, we’ve been here before.

Wind back a decade to visit the ghost of climate politics past, when COP15 was in Copenhagen. This was promised to be a COP with a difference, set to update the 1997 Kyoto protocol (not least because the US had pulled out of it) and build global climate action fit for the 21st century. Climate change was, not unlike today, high on the list of public concerns. Campaign rhetoric was heavy with phrases such as “the time is now” and graphics of ticking clocks. There were new protest movements cropping up, warm words from politicians, as well as hand wringing over the ethics of flying, celeb-fronted concerts to raise awareness and even an Attenborough special on the BBC.

We called it climate chaos back then, rather than a crisis, and it seemed ever so slightly further off still, even if we knew it was already biting. We didn’t have the boost of the youth strikers. Plus, as it was the late noughties, people were still buoyed by the Obama campaign (one PR push was even called “Hopenhagen”). For some reason, lots of people painted themselves blue. But in many ways, it was achingly similar to the past year.

And then it crashed and burned. Eight draft texts and days of talks between 115 world leaders ended with Barack Obama and the Chinese premier, Wen Jiabao, brokering a loose accord which recognised the scientific case for keeping temperature rises to no more than 2C – but, crucially, didn’t contain commitments to cutting the emissions needed to get there.

The climate movement retreated to lick its wounds. Things weren’t helped by the economic crash, which temporarily sapped energy from the cause. Climate activism, like most ongoing protest movements, relies on a steady flow of new blood but much of this was absorbed fighting austerity.

The UN managed to pull things back with the 2015 Paris talks, carefully rebuilding momentum in the preceding years with talk of the “unstoppable” rise of clean energy. These talks even got people talking about the possibility of keeping global heating to 1.5C – perhaps its most important legacy being the commissioning of the IPCC’s 1.5 degrees report. Climate activism had been on the ascendancy before this was published in October last year, but it offered a powerful catalyst, scaring many into taking notice.

The Sydney skyline on 22 November: climate change has been blamed for exacerbating Australia’s bushfire season. Photograph: Dylan Coker/EPA

To look now to the ghost of climate politics future, next year’s Glasgow’s talks are scheduled to be a bumper event; as big as the Copenhagen, Paris or Kyoto talks. They will involve a global stocktake of countries’ emissions reductions targets, and discussions over what action will need to be taken to stay anywhere below 2C warming.

Will the energy we’ve seen globally over the last year and a half maintain itself until then?

Public concern over climate change seems to bubble up every five to 10 years or so, with increasing levels of intensity, and has done since the 1950s. It’s vital that we keep this bubble going not just all the way until the Glasgow talks, but afterwards too.

Climate politics is characterised by short bursts of activism heading towards short-term and often slightly arbitrary deadlines. We’ve been told again and again that the time is now, or at least within a few years, or the planet gets it. It’s understandable in some ways. Global climate action has been dragging its heels for so many decades that climate activists are tired of waiting. And, frankly, we’re scared of the consequences of further inaction.

Yet the nature of the climate fight is that it’s one that will be with us for the long term, and so our activism has to be too. This is partly because we’ve left it so long that we have to deal with the warming we’ve already cooked up for ourselves as well as radical action to avoid more, but it’s also partly the nature of the beast. As climate scientist Kate Marvel neatly puts it, climate change isn’t a cliff you fall off at some particular stop on a thermometer or date in the calendar, it’s more a slope you slide down.

As yet another decade of inaction on the climate crisis comes to an end and we look fresh-faced and hopeful to the next, we need to be ready to look far ahead. The climate movement as a whole must build sustained, long-term relationships with the public rather than bubbles of activity, so that politicians can’t let it drop off their radar. We also need to build resilience, including care of one another, and have strategies for long-term sustained action. At the Paris talks, for example, some NGOs split teams between people who worked on the summit (who could then fall asleep in a heap at the close) and those ready to clean up after. This is the sort of approach that will keep us going.

We don’t have time to wait for the phoenix of climate action to burn out and rise again – 2020 has to be the year we don’t just battle the climate crisis but ensure it’s a fight we stick with.

• Alice Bell is co-director at climate change charity, Possible, and is writing a book on the history of the climate crisis.