There is a two in five chance the Earth is already destined for 1.5 degrees Celsius of warming, even if humans stopped all emissions immediately, a new study has warned.
The chance dramatically increases to 66% if emissions are not cut until 2029, according to the new paper published in peer-reviewed journal Nature Climate Change.
The researchers said the findings underscore the “need for immediate action” to avoid committing to even higher levels of warming.
Under the COP21 Paris Agreement, scientists and governments agreed the world needs to limit global heating to ideally 1.5°C above pre-industrial levels to stave off even more destructive impacts of climate change.
Pollution lingers in the atmosphere and continues to heat the planet for years after it is emitted.
That means “an understanding of the unrealised warming that will take place due to past emissions is needed in order to assess the likelihood of limiting global warming to the targets set in the Paris Agreement,” the study authors said.
Michele Dvorak from Washington University, who led the study, created a computer model of emissions to understand “committed warming” – the knock-on effect of previously emitted greenhouse gases – under current, as well as alternative, emissions pathways.
To keep global warming at 1.5C, global emissions need to be reduced by 45% by 2030 and reach net zero by 2050, the scientific community says.
All countries agreed at COP21 in Paris to regularly update their own climate action plans to reach these goals, and at the COP26 Glasgow climate talks promised to ramp up their plans ahead of this year’s annual COP summit.
But a recent review by think tanks found none of the heavily polluting G20 countries had so far strengthened their plans since COP26.
“Worse, none of them are on track for a 1.5C pathway,” said Tom Evans, geopolitics specialist at climate think tank E3G.
It comes as negotiators today kick off ten days of talks in Bonn, designed to set the stage for the COP27 talks in Egypt in November.
Mr Evans said it is time for the “big powers in the Bonn negotiating rooms to stop playing games with the future of vulnerable countries”.
He urged them to stump up tougher targets and more money – the “two key ingredients to keep 1.5C alive this decade” – in time for the Egypt talks.