UN Secretary-General Antonio Guterres has urged the world to take action against global warming on all fronts. He warned that "the climate time-bomb is ticking."

Guterres delivered a video message on Monday as the IPCC released its latest report on climate change.

The UN chief said, "The rate of temperature rise in the last half century is the highest in 2,000 years." He added, "Concentrations of carbon dioxide are at their highest in at least two million years."

Guterres said the IPCC report shows that the "1.5-degree limit is achievable." But he also cautioned that "it will take a quantum leap in climate action."

He said, "This report is a clarion call to massively fast-track climate efforts by every country and every sector and on every timeframe."

IPCC Chair Hoesung Lee told a news conference in Switzerland, "The pace and scale of what has been done so far and current plans are insufficient to tackle climate change."

Lee said IPCC reports "clearly show that humanity has the knowhow and the technology to tackle" this issue. He said the synthesis report will become a "fundamental policy document for shaping climate action in the remainder of this pivotal decade."