Reduction pathway
Case study · esg-toolkit
A reduction target is one number. The path to it is where the carbon actually goes.
Four fields draw the path, and the two panels under it take figures of their own. Every chart, table and total recomputes.
Problem
Two companies can make the identical commitment, hit it on the same date and put very different quantities of carbon into the atmosphere on the way, because the atmosphere responds to the integral of the path: a linear path removes a fixed share of the base year every year and a compounding path a fixed share of last year, and progress reported against the base year flatters a company that is already behind.
Method
Two pathway shapes, absolute contraction as a straight line and intensity convergence multiplied by the reader's own activity forecast, a budget taken as the area under the path by the trapezoid rule over one year steps, and a diagnostic that inverts the path to solve for the annual cut that still lands on the target.
What it does
Four fields draw the path and the endpoint, the total reduction, the cumulative budget, a chart and a table of every year follow them; a second panel runs the same rate as a linear and a compounding path and prints the gap in percentage points and in extra carbon, and a third marks each reported actual behind or ahead and computes the rate required from the last year entered.
What it refuses to do
It refuses to interpolate a year the reader left blank, and where the years entered are not consecutive the cumulative panel says so and withholds the total rather than computing one across a gap.
It refuses to present 4.2 percent as a rule: it is the floor the SBTi sets under the absolute contraction approach for a near term Scope 1 and 2 target, printed with its publisher and the date it was read, and the page makes neither the upward adjustment for base years later than 2020 nor the separate lower rate for Scope 3.
It refuses to call a target met, because nothing in the arithmetic knows whether the inventory held the same boundary two years running, whether the base year was recalculated after a disposal, or whether a reduction came from decarbonising or from selling the emitting part of the business.
In closing
The tool exists for the two figures a spreadsheet does not print unless somebody thinks to ask for them: the area under the path, and the rate that delay has already made necessary.