Per-SSP permafrost cSoil first-PELT change-point
| SSP | n_models OK | first_cp median | first_cp IQR | warming@cp median (K) | sink→source flips |
|---|---|---|---|---|---|
| SSP1-1.9 | 1 | 2028 | [2028, 2028] | +0.271 | 0/1 |
| SSP1-2.6 | 6 | 2033.5 | [2029, 2034] | +0.517 | 2/6 |
| SSP2-4.5 | 6 | 2029.5 | [2028, 2033] | +0.475 | 1/6 |
| SSP3-7.0 | 6 | 2028.5 | [2028, 2029] | +0.318 | 2/6 |
| SSP5-8.5 | 6 | 2027.5 | [2027, 2029] | +0.363 | 0/6 |
First-break warming threshold crossed in 2026
Cross-model warming-anomaly at first PELT change-point: median = +0.36 ± 0.12 K across all 6 models under SSP5-8.5. Far below the published +1.5–2.0 °C tipping window. Already crossed at 2026 global mean temperature anomaly (~+1.2 K above pre-industrial). The framework reads first regime change as having already happened.
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).
Best mitigation pathway — SSP1-2.6
SSP1-2.6 delays first PELT-CP to median 2033.5 (vs SSP5-8.5 at 2027.5). ~5 yr gain from aggressive mitigation. SSP1-1.9 has only 1 model in the cache (CESM-WACCM not yet run) so the median is unreliable.
Sink → source flip non-monotonicity
Across the 5 SSPs:
- SSP1-1.9: 0/1 models flip sink → source (n=1)
- SSP1-2.6: 2/6 models flip
- SSP2-4.5: 1/6 models flip
- SSP3-7.0: 2/6 models flip
- SSP5-8.5: 0/6 models flip
Sink→source flips are not monotone in forcing. Highest mitigation (0/1) and highest emissions (0/6) both yield zero flips. Intermediate SSPs show 1–2 flips. Framework interpretation: under SSP5-8.5, high warming + high productivity simultaneously boost soil-C influx; net sign holds. Under aggressive mitigation, the cascade stays small and flip detection becomes noise-limited.
cSoil brake-p β values themselves bind against Theorem 3 (median log-range only 0.012–0.018) — Layer-A inconclusive. The first-break warming threshold is the operative finding, not β.
Source: scenario_fan_permafrost.py