Tools chosen: kalshi_direct kalshi_related polymarket_related claude_news gdelt_news wikipedia code_execution

Sub-questions (Fermi decomposition)

Planner reasoning

This is a long-horizon climate question resolvable by a single calendar year exceeding +2.0°C above 1850-1900. The key empirics are the current annual anomaly level (Copernicus/NASA/WMO), the underlying warming trend rate, and the size of interannual variability (El Niño spikes) that could push a single year 0.4-0.5°C above trend before 2050. Market price on Kalshi is the anchor, and a Monte Carlo on trend + variability gives an independent estimate.

# Current state The market resolves YES if any single calendar year before 2050 reaches/exceeds +2.0°C above the 1850-1900 baseline. As of the latest confirmed data (2025), the warmest individual years (2023-2025) sit at ~1.5-1.6°C depending on dataset — meaning roughly 0.4-0.5°C of single-year excursion still needed. Kalshi currently prices this at 76% YES. # Timeline of key events - 2017: IPCC SR15 estimates human-induced warming at ~1.0°C above pre-industrial, rising ~0.2°C/decade (confirmed, IPCC AR6/SR15). - 2023: Global mean anomaly reported at 1.45-1.54°C depending on dataset (Copernicus ERA5 1.48°C; Berkeley Earth 1.54°C; WMO consolidated 1.45°C) — confirmed. - 2024: First calendar year to exceed 1.5°C in most datasets; WMO consolidated 1.55°C; Copernicus/Berkeley Earth/JRA-3Q ~1.6°C; NASA/NOAA just under 1.5°C — confirmed (WMO, Copernicus, Berkeley Earth). - 2025: Copernicus reports 2025 as third-warmest year on record, ~0.13°C cooler than 2024, ~1.5°C range; 2023-2025 three-year average first to exceed 1.5°C — confirmed (Copernicus, Dec 2025 report). - 2026 (reported, per WMO/GDELT items dated 2026-05-28): UN/WMO decadal outlook states 86% chance one year in 2026-2030 will be the hottest on record, and temperatures likely to remain at/near record levels through 2030 — reported, not yet realized. - 2026-08 (reported): Articles reference forecasts of a "strongest El Niño" and warming "kicked into overdrive" — rumored/speculative, unconfirmed as of brief compilation (dates appear to be forward-looking/future press, treat cautiously). # Event Will annual global mean surface temperature anomaly (vs. 1850-1900) reach or exceed +2.0°C in any calendar year before Jan 1, 2050? (KXWARMING-50) # Outcomes to forecast - Yes (single year ≥2.0°C occurs before 2050) - No (no year reaches 2.0°C before 2050) # Kalshi market anchor Current YES price: **76%**. 7-day and 30-day change: 0%. 30-day range 74-83%. Thin market: avg daily volume ~47 contracts over 147 days of data — low liquidity, price likely sticky/inertial rather than reflecting fresh information flow. # Sub-question answers 1. **2023-2025 anomalies (major datasets)** — 2023: 1.45°C (WMO)/1.48°C (Copernicus ERA5)/1.54°C (Berkeley Earth). 2024: 1.55°C (WMO consolidated)/1.60°C (Copernicus, Berkeley Earth, JRA-3Q)/just under 1.5°C (NASA, NOAA). 2025: ~1.5°C range, third-warmest on record, 0.13°C cooler than 2024 (Copernicus). [claude_news] 2. **Decadal warming rate / trend by 2049** — IPCC AR6 benchmark: ~0.2°C/decade (range 0.1-0.3°C/decade), reaching 1°C around 2017. Extrapolated at ~0.2-0.3°C/decade, long-term average 2°C would arrive around 2050s-2060s, but single-year excursions can occur earlier via El Niño spikes. [claude_news, IPCC SR15] 3. **Interannual/El Niño excursion size** — 2023→2024 jump (~0.1-0.15°C) attributed largely to El Niño; Monte Carlo model treats El Niño boosts as +0.15-0.25°C with ~15%/yr occurrence probability. [code_execution] 4. **Dataset dependence** — Materially yes: 2024 anomaly ranged from just under 1.5°C (NASA/NOAA) to 1.6°C (Copernicus/Berkeley Earth/JRA-3Q), a ~0.1-0.15°C spread — comparable in magnitude to the "headroom" needed to cross 2.0°C, meaning dataset choice could shift the crossing year by several years. Rules do not specify which dataset Kalshi uses — a key ambiguity. [claude_news; RULES section is blank] 5. **Expert projections for single-year 2°C exceedance** — Carbon Brief 2025 update models single-year 1.5°C exceedance already occurred (2024) and gives 2°C single-year estimates broadly in the 2040s-2050s depending on dataset; no single authoritative central-year figure was captured in search but directionally consistent with pre-2050 plausibility under current trends. WMO decadal outlook (2026 report) sees near-record/record temperatures continuing through 2030, consistent with sustained upward pressure. [claude_news, gdelt_news] 6. **Kalshi price/comparables** — KXWARMING-50 at 76% YES, stable, low volume. No Polymarket matches found. Related Kalshi climate markets (EU/India/US climate goals) are differently structured and not directly comparable thresholds. [kalshi_direct, kalshi_related, polymarket_related] # Key facts (high-confidence, factual) 1. [WMO/Copernicus] 2024 is confirmed the first calendar year to exceed 1.5°C in most datasets (~1.55-1.6°C). 2. [Copernicus] 2025 was third-warmest on record, slightly cooler than 2024, still >1.4°C. 3. [IPCC SR15] Long-term warming rate ~0.2°C/decade (0.1-0.3°C range) as of ~2017 baseline. 4. [Kalshi] Current YES price 76%, flat over 7/30 days, low liquidity (~47 contracts/day). # Cross-market signals - Kalshi related: No KXWARMING sibling markets found with pricing signal; unrelated climate-goal markets (EU 48.5%, India 68%, US 6.3%) not directly informative for this threshold. - Polymarket: No matching markets found (0/100 scanned). - Sportsbook implied: N/A (not applicable to climate questions). # Analyst opinions and speculation - Carbon Brief (2025): single-year 1.5°C threshold already crossed; models for 2°C single-year exceedance generally point to mid-2040s depending on dataset/trend assumptions (Berkeley Earth central ~2027 for 1.5°C, NOAA later ~2033 — analogous spread would apply for 2°C, shifted later). - Climate Brink: long-term *average* 1.5°C crossing near 2028 at current trend; 2°C average crossing plausibly 2050s-2060s — but this is the average metric, not the single-year metric the market uses (important distinction). - WMO 2026 decadal outlook: 86% chance a 2026-2030 year sets a new record; sustained near-record temperatures expected — supportive of continued upward pressure toward 2°C excursions. - Monte Carlo simulation (code_execution): central estimate ~80-85% probability of a single year ≥2.0°C before 2050, median crossing year ~2042; highly sensitive to trend assumption (43% at low end 0.18°C/decade to ~100% at high end ≥0.26°C/decade). # Directional lean per outcome - **Yes**: Supported by accelerating trend (2024 record, 2023-2025 three-year average already >1.5°C), Monte Carlo central estimate ~80-85%, WMO decadal outlook expecting continued records, El Niño-driven excursions historically add 0.1-0.25°C. - **No**: Requires trend to stay at low end (~0.18°C/decade or less) with no major El Niño spike through 2049 — plausible but modeled at only ~15-20% probability; also possible dataset ambiguity in resolution criteria could favor cooler-reporting datasets (NASA/NOAA), delaying crossing. # Gaps / unknowns - Resolution dataset unspecified in rules — critical ambiguity given ~0.1-0.15°C dataset spread. - No explicit central-estimate published year for single-year 2°C exceedance from major institutions (only inferred/derived via analyst extrapolation and Monte Carlo). - Some GDELT-sourced articles carry future-dated (2026) timestamps of uncertain reliability/context. # Calibration anchors - Kalshi current YES price: **76%** (primary anchor). - Monte Carlo base case: ~80-85% probability, aligning reasonably with Kalshi price. - Precedent: 1.5°C single-year threshold was crossed faster than many pre-2020 projections expected (2024 vs. earlier estimates of late-2020s/2030s), suggesting possible upside risk to Yes.

1. Both forecasts settle within 3-4 points of the Kalshi 76% anchor despite the brief showing extreme sensitivity to trend assumptions (Monte Carlo ranges from ~43% at 0.18°C/decade to ~100% at ≥0.26°C/decade) — this wide sensitivity should either widen their uncertainty or justify a more independent departure from the anchor, not a near-identical convergence to it. 2. Neither forecast does the arithmetic check: at the stated ~0.2°C/decade trend, 24 remaining years yields only ~0.48°C of additional *trend* warming from a ~1.5-1.6°C base, meaning reaching 2.0°C requires trend warming near the *high* end of the IPCC range PLUS a coincident El Niño spike — this "stacking" requirement is understated as "modest" risk in Forecast 1 rather than treated as the central bottleneck. 3. The dataset ambiguity (NASA/NOAA reporting 0.1-0.15°C cooler than Copernicus/Berkeley Earth) is acknowledged by both but not quantitatively incorporated — given rules are silent on which dataset resolves the market, and a cooler dataset could plausibly delay crossing by 5-10+ years, this should arguably pull probability *below* Kalshi's 76%, not support settling above it. 4. Both forecasters treat "long-dated contracts trade below true probability" (Forecast 1) as a reason to nudge YES up, but this is an unsupported general heuristic not evidenced in the brief for climate-specific Kalshi markets, and ignores the equally plausible explanation that thin volume (~47 contracts/day) simply reflects stale, uninformative pricing rather than systematic underpricing. 5. Confidence scores diverge substantially (0.55 vs 0.68) despite nearly identical point estimates (79% vs 80%) — this inconsistency in stated confidence isn't explained by any difference in reasoning depth or evidence weighting between the two, suggesting arbitrary confidence calibration. 6. Neither forecast considers the possibility of decelerating warming from strengthened mitigation/net-zero policy commitments over a 24-year horizon, nor the tail scenario of a major volcanic eruption or aerosol forcing event suppressing temperatures — both are plausible, precedented "No"-favoring tail risks entirely absent from either rationale.

75% (62% confidence)

Yes: 75% No: 25%

Both forecasters converged just above the 76% Kalshi anchor, but the critique correctly flags that the crossing requires stacking: from a de-trended ~1.45-1.5°C level in the mid-2020s, ~24 years at the central 0.2°C/decade gets to roughly 1.95°C, so a single-year ≥2.0°C needs either an above-central trend (aerosol-cleanup-boosted, plausible) or a coincident strong El Niño excursion of +0.15-0.25°C — likely but not assured. The unspecified resolution dataset is a genuine downweight for YES, since NASA/NOAA run 0.1-0.15°C cooler, comparable to the entire remaining headroom, and could push crossing past 2049; neither forecaster priced this quantitatively. Offsetting No-side tails (major volcanic eruption, aggressive mitigation, natural variability lull) also went unmentioned. Netting the Monte Carlo central estimate (~80-85%) against dataset ambiguity and the stacking requirement, I settle marginally below the thin, sticky market at 75%.

Total pipeline time: 260.5s