The UN's weather and climate agency says that the levels of greenhouse gases in the atmosphere reached another record high last year.
According to the World Meteorological Organisation, the global averaged concentrations of carbon dioxide (CO2) reached 405.5 parts per million (ppm) in 2017 - up from 403.3 ppm in 2016, and 400.1 ppm in 2015.
The levels of methane and nitrous oxide in the atmosphere also rose, while scientists also report a resurgence in a 'potent' greenhouse gas called CFC-11.
The CO2 increase was slightly smaller that previous years, with the WMO saying the changes in 2015 and 2016 were influenced by a significant El Niño weather event.
Reacting to the figures, the WMO warns that there's 'no sign of a reversal' in the trend of increases - saying that the gases are resulting in major consequences such as rising sea levels, climate change and more extreme weather.
Overall, the organisation says the warming effect of 'long-lived' greenhouse gases in our atmosphere has increased by 41% since 1990, predominantly the result of CO2.
WMO Secretary-General Petteri Taalas said: "The science is clear. Without rapid cuts in CO2 and other greenhouse gases, climate change will have increasingly destructive and irreversible impacts on life on Earth. The window of opportunity for action is almost closed,
"The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3°C warmer and sea level was 10-20 meters higher than now."
The stark warning from climate experts comes only hours after Donald Trump took to Twitter and appeared to express doubt that global warming exists, despite overwhelming scientific consensus to the contrary.
Brutal and Extended Cold Blast could shatter ALL RECORDS - Whatever happened to Global Warming?
— Donald J. Trump (@realDonaldTrump) November 22, 2018
