That threshold, outlined in the 2015 Paris Agreement, saw countries around the world agree to reduce carbon emissions in a bid to stop our worldwide climate exceeding 1.5C compared to pre-industrial temperatures.
That’s seen as a key landmark because the 1800s is when we really started to pollute the atmosphere.
Beyond that 1.5C point, scientists believe the world’s climate will be irrevocably changed (for the worse).
But, new estimates published in the journal Nature Climate Change on Monday suggest we’re on a path to go above and beyond that level within just six years.
And since the study started in January, that means we actually have closer to five years – so that gives us up until 2029.
Why? Well, we’re being far too slow at cutting back on our carbon emissions, so they are continuing to build up in our atmosphere, making our weather more extreme and alter our planet as we know it.
But, these new estimates are also much worse than the previous time periods scientists provided.
So why are these new estimates putting us at 2029 for exceeding 1.5C?
The scientists say it is actually because we’ve managed to clean up our act when it comes to removing soot and sulphates – other emissions which typically come from air pollution – from the atmosphere.
This is a good thing for the environment as a whole, but it actually has accelerated warming because these particles act as coolants, masking the impact burning fossil fuels have on our planet.
Joeri Rogelj, a climate scientist at Imperial College London, told journalists at a news briefing that the best paths for dodging 1.5C have already disappeared – “and they have been gone for a while,” he added.
Still, the team who worked on the projections said world leaders can still try to work towards limiting it, even if we exceed 1.5C, because every fraction counts.
The carbon budget – the term for the amount of carbon we can pump into the atmosphere, and still have a 50% chance of not exceeding 1.5C – for keeping the temperature it below 2C is 1,220 billion metric tons.
If we kept on at current emissions levels, that would take us to around 30 years to burn through.
However, it remains unclear just how much of our carbon budget is left for us to use before we breach 1.5C.
The budget is currently set at around 250 billion metric tons, according to these new estimates – which doesn’t give us much leeway at all, considering we currently burn a little more than 40 billion metric tons a year.
For comparison, the 2021 UN’s Intergovernmental Panel on Climate Change suggested there were 500 billion metric tons left to use until 2032.
Still, Robin Lamboll, Imperial College of London climate scientist, explained: “It’s not that the fight against climate change will be lost after six years, but I think probably if we’re not already on a strong downward trajectory, it’ll be too late to fight for that 1.5 degree limit.”
The last decade is already on average 1.14C hotter than 19th Century and 2022 was 1.26C hotter.
It’s also worth noting that weather events like El Nino or how much we reduce other emissions of heat-trapping gases, also could alter the 1.5C threshold.
For instance, this year is expected to go above 1.5C because of the high heat levels – but that doesn’t necessarily mean we’ve breached the Paris Agreement terms, as they are meant to look at years as a whole.
Climate negotiations are set to take place next month in Dubai for COP28, where world leaders will debate what can be done to prevent breaching 1.5C.