Will NASA GISS report a global surface temperature anomaly of at least +1.65 °C (vs. 1951–1980) for December 2026?
deadline 2027-01-20
confidence medium
tier 1 evidence
29%Asturna estimate
Resolution criterion
Resolves YES if the NASA GISS file GISTEMP v4 land-ocean monthly means (https://data.giss.nasa.gov/gistemp/tabledata_v4/GLB.Ts+dSST.csv), read for the first time on or after 2027-01-20, shows a value >= +1.65 °C for December 2026 (row 2026, column Dec). The value read at that moment is final; later revisions do not change the outcome. If the value is not yet published on 2027-01-20, the check is repeated until 2027-01-30, after which the question is voided. Also voided if NASA changes the dataset version or the 1951–1980 baseline. Reference at creation: +1.55 °C (October 2026). Data: GISTEMP Team, GISS Surface Temperature Analysis (GISTEMP), version 4, NASA Goddard Institute for Space Studies.
Verified starting state
Computed base rate: 27% of two-month changes in the NASA GISTEMP monthly anomaly since 1990 reached the change implied by this threshold (threshold 1.65 °C rounded up to 0.05 °C; reference 1.55 °C in 2026-10). Overlapping windows: small effective sample.
What pushes it up
- Current October 2026 anomaly is +1.55 °C, only 0.10 °C below the +1.65 °C threshold, suggesting a modest upward trend could push December over the mark [tier 1]
What pushes it down
- Historically only about a quarter of two‑month periods achieve such a large increase, indicating it is relatively uncommon [tier 1]
- No specific forecast or announced data points to a December value ≥ +1.65 °C, leaving the estimate reliant on past frequencies [tier 1]
What would move this number most
The actual December 2026 temperature anomaly when the GISTEMP file is released
How this number is built
| Deadline | 2027-01-20 |
| Base rate | 27% |
| Best evidence | tier 1 · 1 article(s) used |
| Independent runs | 27 · 30 (spread 3 pts) |
| Confidence | medium |
| Evidence cap | not triggered |
| Last revised | 2026-11-13 07:50 |
| Model | openai/gpt-oss-120b (Groq) |
Sources consulted