Scientists gathered from around the world will deliver the verdict on Friday morning in Paris on what the damage is -- how we've already permanently altered the planet.
The news will be heavy -- hard to take.
The exact wording of the report won't be final until the 9:30 a.m. press conference, but the basic science is in.
The world's scientists have produced these consensus reports every five years since 1991, but the biggest change since the last report in 2001 is clearly not in the science.
It's in the audience.
This time around, far more people are ready to listen.
This sea change comes after two years of TV and cinema documentaries and specials, unseasonable weird weather extremes, heat spikes and downpours, backyard bugs, birds and flowers out of synch, disappearing mountain glaciers and ski seasons, as well as a rapidly growing chorus of alarmed politicians.
Already, the planet's news organizations are swarming around the scientists and government representatives huddling in Paris over the final wording.
Daily, the World Wide Web brings in hard news.
The latest includes the estimate by Indonesian scientists that 2,000 of the 18,000 gorgeous islands that comprise their country will, by the year 2030, be lost beneath the waves forever (or at least for a thousand years) because of rising sea level caused by global warming.
That's only 23 years from now. 2000 islands just gone.
Global warming's refugees have already begun to move from some Pacific islands. Some scientists predict such refugees will number in the unthinkable hundreds of millions well before the end of the century.
So, with reality setting in, many more eyes now turn with new appreciation to the hard-won consensus of the Intergovernmental Panel on Climate Change.
It involves the work of more than 2,000 scientists from more than 100 countries and is necessarily conservative due to the slow, inclusive and painstaking nature of the approval process.
"The IPCC is completely unprecedented in world history," preeminent climate scientist Richard Somerville told ABC News.
Somerville, now buried in the closed-door Paris meeting, is also currently moonlighting as historian to write a history of the IPCC.
"There's probably never been anything remotely like it among scientists -- for its global scale and long term assessment of a single problem," he says.
Somerville has worked for decades at California's Scripps Institution of Oceanography alongside other early harbingers of the global warming crisis, which virtually all scientists agree has been caused largely by emissions from the burning of fossil carbon in the form of coal, oil and gas.
The IPCC, whose gestation and founding in the 1980's Somerville witnessed from the inside, is now being recognized by more and more people around the world as the most authoritative single source of information about global warming.
With reality now setting in, more journalists are demanding explanations and predictions from scientists -- especially this week in Paris -- and a small but growing number of scientists are trying to become more articulate for them.
They are trying to avoid the "geek-talk," or scientific jargon, that makes most readers' eyes glaze over.
It's been a bone of contention.