U.N. Secretary General Antonio Guterres called on rich nations to accelerate their shift to "net zero" emissions on Monday after a new assessment from scientists warned there was little time to lose when it came to tackling climate change.

In a recorded address, Guterres described the sixth "synthesis report" from the U.N.'s Intergovernmental Panel on Climate Change (IPCC) as "a survival guide for humanity" and urged developed countries to commit to "net zero" by the earlier date of around 2040.

According to the IPCC, emissions must be halved by the mid-2030s if the world is to have any chance of limiting temperature rise to 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels - a key target enshrined in the Paris accord.

(Reporting by David Stanway in Singapore Editing by Bernadette Baum)