Four key climate change indicators reached record levels in 2021 as the world edged closer to "climate catastrophe", the United Nations warned in a gloomy report published Wednesday.

Greenhouse gas concentrations, rising sea-levels, ocean heat and ocean acidification all set new records in 2021 according to the World Meteorological Organization’s State of the Global Climate in 2021 report.

The last seven years have been the warmest on record and the average global temperature in 2021 was around 1.11C above pre-industrial levels, the report added.