Stopped in their tracks by the pandemic, citizens around the world are once again bracing to mobilise for the planet in a year marked by several major international summits on climate and biodiversity.
In 2019, millions of people, led by student and youth organisations, flooded the world's streets to demand that governments act to stave off the worst effects of global warming.
But then came Covid-19, bringing the global movement to a screeching halt, with lockdowns and travel restrictions forcing mass events to be cancelled and activism to shift online.
"The pandemic hit right at the moment when we were peaking in terms of mobilisation," said Nicolas Haeringer, from the environmental group 350.org.
Youth activists quickly adapted to online activism, and the pandemic may even have helped groups based in richer countries to devise better ways to include activists from developing nations.
The School Strike for Climate movement "was deeply rooted in European youth," said Haeringer.
"The pandemic has been used to rebalance things and build real leadership in global south nations."
While the internet is ideal for laying plans, it is clear that the impetus has waned from movements unable to protest in real life.
"It has been hard for movements," said Clare Farrell, a co-founder of the civil disobedience Extinction Rebellion movement.
"We build relationships through face-to-face work often so we are really looking forward to getting back out to do actions in public space, to meet new people and build the movements again."
Dana Fisher, professor of sociology at the University of Maryland, said that climate activists have spent the last year also campaigning for similar causes in solidarity with other movements.
This includes participating in activism against systemic racism and in helping people of colour gain better access to Covid-19 vaccines.
In the US, "the movement is definitely not stopping, but the tactic of the climate strike is not a dominant form of activism right now and it may never return," said Fisher.
But many youth strikers are undeterred by the turbulent last 12 months.
"We're keeping in touch, it's great and I believe that there will be another youth mobilisation," said Michel Villarreal, a Bolivian student activist.
There are a number of high-profile events in 2021 that activists could use as launch pads for wider activities.
The first is next week with US President Joe Biden's virtual climate summit.
In September, the global congress of the International Union for Conservation of Nature is set to take place in the French port city of Marseille, Covid permitting.
Then comes the COP15 on biodiversity in Kunming, China, in October, followed hot on its heels by the COP26 UN climate talks in the Scottish city of Glasgow.
Groups are already planning a global day of action to "reclaim the initiative", probably at the start of Autumn, said Haeringer.
"It's imperative that we get citizens energised this year to make sure that the powers that be see how widespread support for rapid action really is," added Farrell.
But it remains to be seen how inclusive any climate activity can be.
The global vaccine rollout has been deeply uneven, with stockpiling in richer nations, while poorer countries struggle to get their hands on doses.
"Will the youth movement descend on the streets, express their will for things to change and demand more political courage to implement strong climate policies?" said Amy Dahan, a science historian specialising in climate change at France's CNRS research network.
"It's hard to say."
Swedish activist Greta Thunberg has led calls to ensure that the vaccine rollout is sufficiently equitable to ensure that COP26 has equal representation from all nations.
"It's important to think hard about the experience of the pandemic and all that it's shown us from the social inequalities it's exposed," said Farrell.