Substantial differences in crop yield sensitivities between models call
for functionality-based model evaluation
Abstract
Crop models are often used to project future crop yield under climate
and global change and typically show a broad range of outcomes.
To understand differences in modeled responses, we analysed modeled crop
yield response types using impact response surfaces along four drivers
of crop yield: carbon dioxide (C), temperature (T), water (W), and
nitrogen (N).
Crop yield response types help to understand differences in simulated
responses per driver and their combinations rather than aggregated
changes in yields as the result of simultaneous changes in various
drivers.
We find that models’ sensitivities to the individual drivers are
substantially different and often more different across models than
across regions.
There is some agreement across models with respect to the spatial
patterns of response types but strong differences in the distribution of
response types across models and their configurations suggests that
models need to undergo further scrutiny.
We suggest establishing standards in model evaluation based on emergent
functionality not only against historical yield observations but also
against dedicated experiments across different drivers to analyze
emergent functional patterns of crop models.