# Will the extent of the Arctic sea ice be below 4.0 million square km between December 19, 2025 and October 01, 2026

> Below 4.8 million sq km leads at 96%, runner-up 89% across 6 winner-take-all outcomes — refreshed 52 min ago.

URL: https://simplefunctions.dev/odds/arcticicemin
Updated: 2026-09-07T11:21:01.961Z
Category: general
Status: active
Closes: 2026-10-02

## Headline

- Leader: Below 4.8 million sq km at 96%
- Runner-up: Below 4.6 million sq km at 89%
- Outcomes: 6 (winner-take-all)
- Venue: Kalshi (6 contracts)
- 24h volume: $19

## Bound contracts (6)

| Outcome | Price | 24h | Volume | Venue | Slug |
|---|---|---|---|---|---|
| Below 4.8 million sq km | 96¢ | +1pp | $0 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-48-kalshi-kxarcticicemin-26oct01-t4.8 |
| Below 4.6 million sq km | 89¢ | ±0 | $0 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-46-kalshi-kxarcticicemin-26oct01-t4.6 |
| Below 4.5 million sq km | 63¢ | −5pp | $12 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-45-kalshi-kxarcticicemin-26oct01-t4.5 |
| Below 4.4 million sq km | 41¢ | −3pp | $1 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-44-kalshi-kxarcticicemin-26oct01-t4.4 |
| Below 4.3 million sq km | 12¢ | −1pp | $5 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-43-kalshi-kxarcticicemin-26oct01-t4.3 |
| Below 4.2 million sq km | 9¢ | +1pp | $0 | kalshi | /markets/will-the-extent-of-the-arctic-sea-ice-be-below-42-kalshi-kxarcticicemin-26oct01-t4.2 |

## 30-day trajectory

| Day | Below 4.8 million sq km | Below 4.6 million sq km | Below 4.5 million sq km |
|---|---|---|---|
| 2026-08-08 | 92 | 78 | 69 |
| 2026-08-24 | 93 | 78 | 65 |
| 2026-08-30 | 94 | 77 | 54 |
| 2026-08-31 | 95 | — | 52 |
| 2026-09-02 | 97 | 81 | 58 |
| 2026-09-05 | — | 89 | 68 |
| 2026-09-06 | — | — | 63 |

_29 days of price history captured. Each row is the daily mean of intraday 5-min captures._

## What moved the line

- 2026-09-05 · Below 4.5 million sq km +15pp 53→68¢ · kalshi
- 2026-09-04 · Below 4.4 million sq km +10pp 36→46¢ · kalshi
- 2026-09-03 · Below 4.4 million sq km +8pp 28→36¢ · kalshi
- 2026-09-03 · Below 4.3 million sq km −7pp 15→8¢ · kalshi
- 2026-09-05 · Below 4.2 million sq km +6pp 2→8¢ · kalshi

## Analysis

This contract asks whether Arctic sea ice will shrink to below 4.0 million square kilometers at some point between mid-December 2025 and early October 2026. The 91% probability reflects trader expectation that ice extent will reach this threshold during the period, driven by long-term declining Arctic ice trends and seasonal summer melt cycles. Arctic sea ice typically reaches its annual minimum around September, making that window critical to resolution. The estimate could shift if 2026 experiences atypical weather patterns, reduced melt due to cooler temperatures, or if historical decline rates slow unexpectedly. The main driver is the seasonal summer minimum: if ice extent dips below 4.0 million km² during the boreal summer or early fall, the contract resolves to YES. The exact measurement will depend on data from satellite monitoring agencies like NSIDC, typically released monthly.

### Key factors

- Arctic sea ice has declined from ~7.5 million km² in 1980 to ~4.2–4.7 million km² in recent September minima, establishing a downward baseline
- The 2025 summer and fall months represent the highest-probability window for reaching sub-4.0 million km² levels, as seasonal melt is most pronounced August through October
- September 2024 minimum ice extent was approximately 4.28 million km², making 4.0 million km² plausible but not guaranteed under typical conditions
- Resolution depends on official NSIDC or equivalent satellite data; anomalous weather (volcanic cooling, stratospheric circulation changes) could slow melt and reduce likelihood
- The contract spans 9+ months, increasing probability that at least one day will cross the threshold rather than requiring sustained sub-4.0 conditions

## Methodology

Headline is the **leader's price**, not an arithmetic mean — averaging disjoint winner-take-all outcomes is meaningless. Per-outcome prices come from the venue's last-traded mid; cross-venue values are simple means across contracts on each venue.

## How to use this data

- HTML: https://simplefunctions.dev/odds/arcticicemin
- JSON: https://simplefunctions.dev/api/public/odds?slug=arcticicemin

## License

CC-BY-4.0. Attribute "SimpleFunctions" with a link to https://simplefunctions.dev. See https://simplefunctions.dev/legal for terms.