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

30-day trend

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.

• ›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

What moved the line

• Sep 5Below 4.5 million sq km↑15pp53→68¢ · Kalshi
• Sep 4Below 4.4 million sq km↑10pp36→46¢ · Kalshi
• Sep 3Below 4.4 million sq km↑8pp28→36¢ · Kalshi
• Sep 3Below 4.3 million sq km↓7pp15→8¢ · Kalshi
• Sep 6Below 4.5 million sq km↓6pp68→62¢ · Kalshi

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How we compute these odds