Earth to warm up to 2.9C even with current climate pledges: UN

Countries' greenhouse gas-cutting pledges put Earth on track for warming far beyond key limits, potentially up to a catastrophic 2.9 degrees Celsius this century, the UN said Monday, warning "we are out of road."

The UN Environment Programme's annual Emissions Gap report is released just ahead of crucial COP28 climate talks in Dubai and will feed into the global response to a sobering official "stocktake" of the failure to curb warming so far.

Taking into account countries' carbon-cutting plans, UNEP warned that the planet is on a path for disastrous heating of between 2.5 degrees Celsius and 2.9 degrees Celsius by 2100. Based just on existing policies and emissions-cutting efforts, global warming would reach 3 degrees Celsius.

But the world continues to pump record levels of greenhouse gases into the atmosphere, with emissions up 1.2 percent from 2021 to 2022, UNEP said, adding that the increase was largely driven by the burning of fossil fuels and industrial processes.  

UN Secretary-General Antonio Guterres said the world "must reverse course" and called for a clear signal at the COP28 meeting that the world was preparing for a decisive move away from polluting coal, oil and gas. 

The 2015 Paris Agreement saw countries agree to cap global warming at "well below" 2 degrees Celsius above preindustrial times - with a safer limit of 1.5 degrees Celsius if possible.

Nearly 1.2 degrees Celsius of global heating so far has already unleashed an escalating barrage of deadly impacts across the planet.

By 2030, UNEP said, global emissions will have to be 28 percent lower than current policies would suggest in order to stay below 2 degrees Celsius, and 42 percent lower for the more ambitious limit of 1.5 degrees Celsius.

Under the Paris deal, countries are required to submit ever deeper emission cutting plans, known as Nationally Determined Contributions (NDCs). 

UNEP found that fully implementing "unconditional" NDCs for 2030 - which countries plan regardless of external support - would give a 66 percent likelihood of Earth's average temperature rising by 2.9 degrees Celsius by 2100.

Scientists warn that warming of these levels could render vast swathes of the planet essentially uninhabitable for humans and risk irreversible tipping points on land and in the oceans. 

Conditional NDCs - which rely on international funding to achieve - would probably lower this to a still catastrophic 2.5 degrees Celsius temperature rise this century, it said.  

If all conditional NDCs and longer-term net zero pledges were met in their entirety it would be possible to limit temperature rise to 2 degrees Celsius, said UNEP, adding that even in the most optimistic scenario, the chance of limiting temperature rise to 1.5 degrees Celsius is just 14 percent. 

Guterres called for "an explosion of ambition" regarding countries setting their NDCs - which are due to be updated by 2025.