A major UN climate change report being published later today is expected to act as a "999 emergency call" for the world to take action.
The findings are based on thousands of scientific papers and will set out the scale of change since 2013.
It will deliver a stark warning on how fast the Earth is heating up, as well as the role played by humans in the process.
The Intergovernmental Panel on Climate Change (IPCC) is expected to warn that a 1.5° rise in the Earth's temperature will be reached 10 years earlier than expected.
Climatologist Professor John Sweeney from Maynooth University says the report will have a clear message.
He said: "This report is one that's really telling us we've mismanaged... that we have really not handled the stewardship of this panel well, and that we're going to suffer really extreme consequences if we don't take radical action in the next year or two years.
"It's not a wake-up call - we've had those. This is a 999 emergency call for the state of the planet.
"What it's telling us really is that we're running out of time very rapidly."
He said it was expected the world would have had a decade or two to make major efforts to decarbonise societies, but it's now expected major 'tipping points' will arrive far sooner.
Meanwhile, hundreds of firefighters are currently battling wildfires in parts of Europe, fuelled by soaring temperatures.
Evacuations are continuing on the Greek island of Evia - with scenes there likened to a 'disaster movie'.
Dangerous blazes have started north of Athens, killing a volunteer, while efforts to extinguish fires in Turkey are into the 13th day.
The US state of California is also experiencing its second-largest single wildfire ever - the so-called Dixie Fire.
The blaze covered around 460,000 acres of land as of Sunday morning local time.
Over 400 buildings have already been destroyed, while thousands of people have been forced to flee their homes as the blaze spreads.