Similar reports on climate trends released by the US space agency NASA and the US National Oceanic and Atmospheric Administration (NOAA) confirmed that previous year was the fourth warmest in modern times.
"Across the globe, 2018 was extremely warm, with only a few places that were below our normal period [which runs from 1951 to 1980]", Gavin Schmidt, a climate scientist and director of NASA's Goddard Institute for Space Studies, said during a news conference held to announce the report. The past five years are, collectively, the warmest years in the modern record.
The US government's National Oceanic and Atmospheric Administration (NOAA) said that last year's average temperature was 14.69°C, which is 0.79°C warmer than the 20th-century average.
Given that we desperately want to avoid rising above that global average temperature to avoid climate catastrophe for millions - if not billions - of people, now is the time to take climate action seriously, and begin the rapid transition of the global economy over to a low-carbon one, that relies on green, renewable energy.
Weather dynamics mean warming affects regions in different ways.
"The 20 warmest years on record have been in the past 22 years".
"Over the next five years the high temperatures seen recently are likely to be sustained and that further warming may well occur, perhaps reaching new record levels for annual average temperatures", he said.
The British Met Office, which also contributes data to the WMO, said temperatures could rise to 1.5C above pre-industrial times, for instance if a natural El Nino weather event adds a burst of heat. In addition, mass loss from the Greenland and Antarctic ice sheets continued to contribute to sea level rise.
Nasa's data was compiled by 6,300 weather stations around the world and was compared against information stretching back to 1880. Taking this into account, NASA estimates that 2018's global mean change is accurate to within 0.1 degree Fahrenheit, with a 95 percent certainty level.