Includes processes like direct/diffuse light, precipitation (and timing and extremes of that), net photosynthesis, species competition, and others
Metric
An IPCC region's most produced crop (by total calories) has its yield reduced by more than 20% relative to a hypothetical production level associated with the future climate without SAI (i.e. the warmer world), and holding all else constant
Uncertainty
The competing processes mean we are reliant on modelling here. Clark et al. gives analysis framed similarly to this metric, but does not allow a direct quantification of it. Uncertainty is therefore not well bounded. Xia et al., 2016 calculates an increase in ratio of diffuse to total radiation to be below 0.4 under SAI, with benefits to plant productivity peaking at 0.4-0.45.
Decision relevance
A 20% reduction of crop yields across an entire IPCC reference region would represent a large impact which would materially change the cost-benefit for potentially multiple countries.