FLAGRI Scenario Builder · settings & clarification Working draft — Page 4 of a multi-page builder
FLAGRI Scenario Builder · Page 4 of 5

Conditions

How bad are the growing conditions? One number drives it: how far crop yields fall. Normal conditions are 0%. The study's severe case — a 150 Tg nuclear winter — cuts New Zealand yields by 61%.1 The same cut applies to every crop, including the canola meant to replace the fuel.

Calculated effective yields — what a hectare still gives at the current reduction
Reduction
Wheat
kg/ha (paper: 9,900)
Potatoes
kg/ha (paper: 90,000)
Dairy
kg solids/ha (paper: 1,232)
Canola
kg seed/ha (paper: 3,100)
Lower yields mean more land and more diesel for the same food — and more canola land for the same fuel.

Yield reduction

Paper default

The percentage lost from every crop's normal yield. 0% is the paper's baseline; 61% is its severe nuclear-winter case.1 Anything in between is yours to explore — drought, volcanic ash, a milder winter.

Yield reduction — %paper cases: 0 · 61
Worth knowing: Xia et al. stress that nuclear-winter impacts are deeply uncertain — anywhere from single-digit to near-total crop loss depending on scenario and place. Treat any single percentage as a what-if, not a forecast.

 

What the scenarios mean

Guide

"Tg" is teragrams of soot lofted into the stratosphere by nuclear conflict — the driver of nuclear winter. Modelling by Xia et al. (2022)1 translates soot into yield loss for New Zealand:

ScenarioNZ yield loss
Normal conditions0%
Regional conflict · 5 Tg7.9%
Severe nuclear winter · 150 Tg61%
Worth knowing: a plain trade disruption is different — ships stop, fuel runs short, but the sun still shines. For that story, keep yields at 0% here and let the Fuel & Transport settings carry the strain.

Future addition: intermediate soot scenarios (16–47 Tg) if author-endorsed figures are available.

How it's applied

Guide

One factor, applied uniformly to wheat, potatoes, dairy pasture and canola — matching the paper. Cutting the biofuel crop too is what makes severe scenarios bite twice: less food per hectare, and less fuel per canola hectare.

Wheat9,900 kg/ha
Potatoes90,000 kg/ha
Dairy (solids)1,232 kg/ha
Canola (seed)3,100 kg/ha
Worth knowing: real crops respond differently — Xia's modelling covered four crops and marine fish, and the dairy pathway (soot → pasture → milk) is a simplification. Uniform application is a modelling choice the paper makes and this tool keeps.

Future addition: per-crop reduction factors as a research-mode option.

⠿ Boxes are self-contained settings modules — drag a header to reorder. The same module can be placed on any page of the builder later.

References for this page

  1. Xia L, et al. (2022) — nuclear-winter crop modelling: 5 Tg of stratospheric soot ≈ 7.9% NZ yield reduction; 150 Tg ≈ 61% (as used in Boyd et al. 2024, Table 2). The authors emphasise the impacts are highly uncertain.
  2. Boyd M, Ragnarsson S, Terry E, Payne B & Wilson N (2024). Risk Analysis. DOI 10.1111/risa.14297 — the reduction is applied to food yields and to the biofuel feedstock yield alike.

In the full builder, all references live on one dedicated page; boxes carry only the small numbers.