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

With this year expected to be the hottest in human history, UNEP said "the world is witnessing a disturbing acceleration in the number, speed and scale of broken climate records".

But the report said humanity is continuing to pump record levels of planet-heating greenhouse gases into the atmosphere -- largely from fossil fuels.

It warned that taking into account countries' decarbonisation plans, the planet is on a path for disastrous warming of between 2.5C and 2.9C by 2100. Based just on existing policies and emissions-cutting efforts, the world would heat 3C.

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

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