2020 will be one of the three warmest years on record globally, according to a new State of the Global Climate report from the World Meteorological Organisation (WMO).

An agency of the United Nations, the WMO said only 2016 had been hotter than 2020 so far — and only by a small margin.

"The average global temperature in 2020 is set to be about 1.2 degrees Celsius above the pre-industrial [1850-1900] level," WMO secretary-general Petteri Taalas said.

According to the report, the past six years were the hottest six years in history.

"Their records go back to the mid 19th century, so the record's now 170 years long," said Emeritus Professor Neville Nicholls from the School of Geography and Environmental Science at Monash University.

"The top six warmest years have all occurred in the past six years. Now, that's an amazing statistic to a statistics nerd like me," he said.

Read the full article on the ABC News website, featuring commentary by Prof Nerilie Abram