Solomon Hsiang's analogy is blunt: CO₂ is garbage we never paid to dispose of, and the bill accrues interest. Burke et al. quantify that interest. One tonne emitted in 1990 caused roughly $180 in global damages by 2020. That same tonne will inflict approximately $1,840 more through 2100. Ten times the cost already incurred, from emissions already in the atmosphere.
The crop losses, the productivity declines, the insurance premiums climbing every renewal cycle. All of it represents about a tenth of what those same emissions will ultimately cost. The compounding doesn't stop because we've stopped emitting. CO₂ lingers for centuries, suppressing economic output each year it persists. The bill is mostly still ahead of us.