It will be the clearest declaration yet on how an overheating world is hammering our oceans and frozen regions.
Scientists have been meeting in Monaco to finalise a report on the seas and the cryosphere.
Released on Wednesday, it will show how the oceans have been a friend, helping us cope with rising temperatures.
But it will warn that warming is turning the seas into a huge potential threat to humanity.
Researchers from the Intergovernmental Panel on Climate Change (IPCC) were encouraged by Prince Albert II and the Monaco government in 2015 to produce a special report on the oceans and cryosphere - the Earth's surface where water is frozen solid.
For the past three years, the scientists have been reviewing hundreds of published papers on how climate change affects the seas, the poles and glaciers.
Their report will track the flow of water from the frozen tops of mountains to the bottom of the seas, and how this is changing in a warmer world.
