"Commitment" Does Not Mean "Cap"
Climate negotiators, and even academics, habitually speak of commitment as if the only possible commitment is a commitment to an emissions cap. That confusion locks us into the one type of commitment least likely to be accepted in the developing world.
This has caused a huge problem in our negotiations with China. Most believe the US Senate will not commit to a strong climate policy until China commits to a strong policy. This is likely true. But what if China committed to tax coal and oil at $30 per ton of carbon? The US could then pass a cap with a price ceiling at $30 per ton, and US industry would be completely safe from unfair competition, and we would know China was putting in at least as much effort.
Although we believe a realistic deal will require more than just these two pieces, the point is that other commitments besides caps can be just as meaningful.