A massive alliance of more than 11,000 scientists have signed, sealed and delivered an important message to the world: if we don't make rapid, deep and lasting changes to our lives, they write, there will soon come "untold human suffering".
For more than 40 years, the word's scientists have warned of a looming climate crisis, and yet so far, their cries have been met with little attention and even fewer changes.
Now, in the throes of a global emergency, with the echoes of their foresight gradually fading, experts have no choice but to try, try again.
"Scientists have a moral obligation to warn humanity of any great threat," says environmental scientist Thomas Newsome from the University of Sydney.
"From the data we have, it is clear we are facing a climate emergency."
Two years after authoring one of the most talked about climate papers - signed by the largest international group of scientists ever - Newsome and his colleagues have penned another urgent warning to the world.
Encouraged by the recent global surge in environmental concern, their paper explores four decades-worth of publicly available data, covering energy use, surface temperature, population, deforestation, polar ice, fertility rates, and, of course, carbon emissions.
Published for the first time now, it's already gathered an impressive signatory that falls just short of the first, including scientists from more than 150 different countries.