After joking about this at work, I landed on the most cursed scale I could think of... pT = log10 FPW.
Pros: no bottom to scale, increasing negative values asymptotically approach absolute zero. Water freezes at zero.
1 pT is almost exactly the melting point of iridium. Lightning bolts are around 2 pT. Boiling points of neon and helium are in the neighborhood of -1 and -2.
Spell: fix this. Result: this is fixed.