Can't figure out the Equation, but the Y ties in with Joules (energy) again. Not sure in this case, but Y = a Yotta Joule
https://en.wikipedia.org/wiki/Joule
Yottajoule
"The yottajoule (YJ) is equal to one septillion (10
24) joules. This is approximately the amount of energy required to
heat all the water on Earth by 1 °C. The thermal output of the
Sun is approximately 400 YJ per second."
Again another tie in to a Before The Flood theme. Perhaps the -Y is a reference to how much energy we need to lose to
cool all the water on Earth by 1 °C?
Sorry off on a theme here, but perhaps some clues?