Eight cascades. Five futures. The framework projects each forward.
Each scenario page reads what one observable does under five emissions pathways — from the IPCC's most aggressive 1.5°C trajectory (SSP1-1.9) to no-mitigation continued fossil fuels (SSP5-8.5). The pattern across observables — which respond to mitigation, which don't — is the headline of the Mitigation section.
Climate Mitigation Atlas — \(\beta\) by observable × emissions pathway
Each cell's colour is one number — the rate exponent \(\beta\). Green = stoppable (returns to rest). Orange = super-rate. Red = locked-in.
Click any cell for the full reading: \(\beta\), cross-model dispersion, theorem anchor, and the source code on GitHub.
How to read this chart · what the SSPs mean
The axes
- Rows: 8 climate observables — what is changing.
- Columns: 5 emissions pathways from "very aggressive mitigation" (left) to "no mitigation" (right).
- Cell colour: the rate exponent \(\beta\). Below 1 is stoppable; above 1 is locked-in.
- Cell label: the actual \(\beta\) value cross-model median.
The five emissions pathways (SSPs)
- SSP1-1.9 — ~1.5°C. Aggressive net-zero by mid-century. Paris lower bound.
- SSP1-2.6 — ~2°C. Moderate mitigation. Net-zero by ~2070.
- SSP2-4.5 — ~2.7°C. Current policies, middle-of-the-road.
- SSP3-7.0 — ~3.6°C. Regional rivalry, fragmented action.
- SSP5-8.5 — ~5°C. Continued fossil-fuel growth, no mitigation.
SSPs (Shared Socioeconomic Pathways) are the IPCC's standard set of emissions futures. The number after the dash is the radiative forcing in 2100 (W/m²).
What each row tells you at a glance
Stoppable
Atmospheric CO₂ →
Deeply sub-rate under SSP1-1.9 / SSP1-2.6. β crosses 1 at 2038 under SSP5-8.5. Aggressive mitigation works on the trajectory itself.
Stoppable in aggregate
Sea-level rise (with components) →
Aggregate is sub-rate under SSP1-1.9 (β = −1.12). The Antarctic component is super-rate (β = +3.76) under the same pathway. Aggregate hides the truth.
Already crossed
Permafrost →
First-break warming threshold +0.36 ± 0.12 K — already exceeded at +1.2 K observed. The threshold is in the past. Best pathway (SSP1-2.6) only delays first change-point by ~5 years.
σ_cross paradox
Arctic sea-ice →
Cross-model disagreement is 7× wider under SSP1-1.9 than under SSP5-8.5. The forcing signal disappears beneath internal variability. Aggressive policy assessments need wider uncertainty bands, not narrower.
σ_cross paradox
AMOC →
Same paradox as sea-ice. σ_cross-best is SSP5-8.5 but is meaningless physically — it just means models agree under high forcing because the signal dominates. The Smeed et al. 2008–2012 weakening claim does not survive a BIC change-point test.
Inconclusive
Amazon NPP →
5/26 models project decline under SSP1-2.6; similar split under SSP5-8.5. Genuine model disagreement, not framework limitation. The framework declines to call this one.
Pattern-4 conservation
Energy budget →
Closed-domain conservation across ocean, ice, land, atmosphere reservoirs. 78% closure against CERES top-of-atmosphere flux — reproduces Trenberth–Fasullo's "missing energy" finding from first principles. (Scenario fan ~24% complete.)
Counterfactual
Stratospheric ozone →
Without the 1987 Montreal Protocol, the framework reads Antarctic ozone hitting zero by 2010. 165σ separation between counterfactual and observed recovery. The original intervention was the principal lever.
Coverage and provenance
| # | Observable | Statistical fan | CMIP6 SSP fan | Status |
|---|---|---|---|---|
| 23 | CO₂ trajectory | 9 rate offsets | 5 SSPs (forced) | Complete |
| 16/17 | Arctic sea-ice | 9 rate offsets | 60 model-SSP cells (4 SSPs) | Complete |
| 16/29 | AMOC | 5 RAPID rate offsets | 46 model-SSP cells (3 SSPs) | Complete |
| 16 | Amazon NPP | — | 76 model-SSP cells (3 SSPs) | Complete |
| 24 | Sea-level rise | 5 rate offsets per shadow | 5 SSPs (AR6) | Complete |
| 26 | Permafrost | — | 25 model-SSP cells (5 SSPs) | Complete |
| 18 | Energy budget | — | 6/25 model-SSP pairs (4 SSPs) | Partial — ~24% |
| 25 | Stratospheric ozone | 7 scenarios + counterfactual | — | Complete |
Source documents: scenario_fan_synthesis.md for the cross-observable synthesis; per-observable scripts under domains/climate/experiments/.