Current commitments to cut greenhouse gas emissions put the planet on track for an average 2.7 degrees Celsius temperature rise this century, a United Nations report said on Tuesday, in another stark warning ahead of crunch climate talks.

Governments will be in the spotlight at the COP26 conference next week to meet a deadline of this year to commit to more ambitious cut pledges, in what could be the last chance to put the world on track to limiting warming to below 2C above pre-industrial levels and ideally to 1.5C.

As extreme weather events ranging from wildfires to floods have hit countries around the world, a U.N. report in August warned that global warming due to greenhouse gas emissions could breach 1.5C in the next two decades.

But British Prime Minister Boris Johnson said on Monday it was "touch and go" whether the most important round of U.N. talks since the Paris Agreement in 2015 will secure the agreements needed to tackle climate change.

And the U.N. World Meteorological Organization said ahead of the two-week event which begins in Glasgow, Scotland on Sunday that greenhouse gas concentrations hit a record last year and the world is "way off track" in capping rising temperatures.

The annual "emissions gap" report by the United Nations' Environment Programme (UNEP), which measures the gap between anticipated emissions and those consistent with limiting the temperature rise this century as agreed in the Paris accord, said updated pledges only reduce forecast 2030 emissions by an additional 7.5%, compared to the previous commitments.

If continued throughout this century, this would lead to warming of 2.7C, slightly less than the 3C UNEP forecast in its last report. A 30% cut is needed to limit warming to 2C and a 55% cut is needed to limit to 1.5C.

It said current commitments to net zero could limit warming to around 2.2C by the end of the century, but 2030 pledges so far do not put major emitters on a clear path to this.