Following up on earlier discussions on the Mass. vs. EPA Supreme Court oral arguments and specifically on the issue of standing and redressibility, here are some numbers on the effects of the emissions reductions being discussed in the oral arguments and their effects on future sea level rise.

Assume the following:

A. Sea level will at an average of 3 mm/year

B. Of this 1 mm/year is already committed to (e.g., due to non-human causes, human caused due to past GHG emissions)

C. Emissions reductions have an instantaneous effect on sea level rise and that effect if proportional to the total emissions (of course this is not true, but makes this exercise easier, and makes my analysis conservative as emission reductions actually have less than this effect)

Under these assumptions what would the effects of EPA regulation as discussed yesterday be on future sea level rise?

Let’s go out to 2100 and assume that regulations are in place and successful by 2010 (not realistic, but again conservative).

90 years of Business as usual (BAU) * 3 mm/year = 270 mm = 10.63 inches

90 years of BAU minus 2.5% = 90 + 175.5 = 265.5 mm = 10.45 inches

Time delay until 270 mm is reached = 18 months

(If you would prefer to apply the effects of emissions reductions to the full 3 mm/year, then the numbers are 263.25 mm = 10.36 inches = 27 months)

What does this mean?

The maximum effect if reducing global emissions by 2.5% (i.e., as suggested in oral arguments yesterday) would be to reduce projected sea level rise by a less than a fifth of an inch in 2100. In other words, the sea level that would have occurred in January, 2100 would be put off until June, 2101. If you’d prefer to apply the effects of future emissions reductions of 2.5% to the total sea level rise (i.e., ignoring the existing commitment) then the numbers are a quarter inch and March, 2102.

Are these meaningful with respect to redressing damages? In my opinion, no they are not. In fact, I would argue that there is in fact no difference in damages that exists at a difference of less than a quarter inch of sea level.

Seems to me that these numbers might have been raised in the arguments at some point.