A damning new UN report published Sunday said the world is falling badly behind in the race to avert climate disaster because of runaway warming, with the five-year period ending 2019 set to be the hottest ever.

It comes ahead of a major UN climate summit Monday that will be attended by more than 60 world leaders, as Secretary-General Antonio Guterres pushes for countries to increase their greenhouse gas reduction targets.

The report "highlights the urgent need for the development of concrete actions that halt global warming and the worst effects of climate change," said its authors, the Science Advisory Group to the summit. Average global temperature between 2015 and 2019 is on track to be the hottest of any five-year period on record, a report of the World Meteorological Organization said.

The period "is currently estimated to be 1.1 degrees Celsius above pre-industrial (1850-1900) times and 0.2 degrees Celsius warmer than 2011-2015," it said.