Keywords: Key category analysis | ranking and scoring
What data needs were addressed? To prioritize which inventory key categories should be the focus for improvement.
Why was the data needed? The UK’s inventory applies Approaches 1 and 2 to key category analysis. In the latest inventory, 39 inventory categories are identified as key categories. With limited resources for inventory improvement, a method was needed to help prioritize key categories.
Methods used: Ranking and scoring.
How was the data gap addressed? The UK has developed a ranking system to prioritize key categories. The Key Category Analysis (KCA) ranking system works by allocating a score based on how high categories rank in the base year and most recent year level assessments and the trend assessment for the Approach 1 KCA including LULUCF. For example, in the base year (1990) level assessment, enteric fermentation from cattle was the 10th largest emission source; the 7th largest in the most recent (2018) level assessment; and ranked 14th in the most recent trend assessment. This category is therefore given a score of 10+7+14=22. The categories are then ranked from lowest score to highest, with scores that are equally resolved by the most recent year level assessment. In the 2018 KCA ranking results, enteric fermentation from cattle was ranked 9th out of all key categories.
The assessments used in this ranking exercise are only those including LULUCF, because if the additional excluding LULUCF assessments were also used, the LULUCF sectors would only be included in half of the assessments and would, therefore, give an unrepresentative weighting.