The most optimistic target envisaged by the Paris climate deal is still within our reach, scientists say – as long as we act urgently to seize this pivotal moment of hope and opportunity.

A new analysis has found that the agreement's most ambitious goal of limiting the increase in global average temperature to 1.5°C above pre-industrial levels isn't just aspirational – it's still a scientific possibility the world can realise if we act right away.

The deal, drafted in 2015, saw the global community come together in a historic agreement to limit global warming "to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change".

While the 1.5°C limit was envisaged as an aspirational target worth striving for, many scientists expressed doubt over whether it was viable, with one study finding we had just a 1 percent chance of hitting the goal, while others suggested even the 2°C limit isn't realistic.

But those grave estimates – and the sinking feelings of despair and resignation they inevitably arouse – may have been premature.

A new international study based on revised modelling of climate data contained in the IPCC Fifth Assessment Report suggests the 1.5°C benchmark is "not yet a geophysical impossibility", provided countries deliver upon more ambitious emission reductions than those already pledged.

"Our estimates suggest that we would have a remaining carbon budget equivalent to around 20 years at current emissions rates for a 2-in–3 chance of restricting end-of-century warming to below 1.5°C," explains one of the team, Richard Millar from Oxford University in the UK, in an explanatory post at Carbon Brief.

"This suggests that we have a little more breathing space than previously thought to achieve the 1.5°C limit."

The carbon budget – the total amount of greenhouse emissions we can produce and still hit the 1.5°C limit – in this case is around 240 billion tonnes of carbon (880 billion tonnes of CO2), per the team's new estimates.

If we can limit ourselves to that level of carbon output – from 2015 onwards, so the clock is already ticking – then we've got a good chance of keeping the rise in global temperatures to less than 1.5°C above pre-industrial levels by the end of the century.

Previous estimates using the same data had suggested the carbon budget was around four times lower, meaning we only had somewhere between three and five years (from 2015) before exceeding the carbon limit.

Thankfully, if the revised tally is right, we've been given another much-needed chance to right our carbon wrongs.

"That's about 20 years of emissions before temperatures are likely to cross 1.5°C," one of the researchers, climate scientist Myles Allen from Oxford University told The Times.

"It's the difference between being not doable and being just doable."

But it definitely won't be easy.

Those 880 billion tonnes of CO2 is what we'd normally emit in about 20 years, so nations will have to act fast to make sure the cuts happen – but the researchers think we can do it.

With the world adopting clean and renewable power at a rate never before seen, the global opportunity to turn away from coal and other heat-trapping sources of atmospheric pollution has never been greater, the researchers say.

"We're in the midst of an energy revolution and it's happening faster than we thought, which makes it much more credible for governments to tighten the offer they put on the table at Paris," one of the team, Michael Grubb from University College London in the UK, told The Times.

It's not every day climate scientists give you a 20-year reprieve on environmental armageddon. Here's hoping world leaders and the international community at large make the most of this brilliant, beckoning opportunity.

This is our time.

The findings are reported in Nature Geoscience.