{
  "id": "2026-10-08-antarctic",
  "region": "antarctic",
  "status": "published",
  "draftedAt": "2026-10-08",
  "publishedAt": "2026-10-08",
  "dataThrough": "2026-10-06",
  "headline": "Antarctic sea ice is below its seasonal average.",
  "value": "9.4",
  "unit": "%",
  "valueLabel": "Below the same-day average",
  "baselineLabel": "1981\u20132010 reference period",
  "copy": "Sea ice covered 16.706 million km\u00b2 on 6 Oct 2026. That puts it below the historical comparison range used here. Extent describes the area covered by sea ice. This daily comparison helps track the seasonal ice cover; it does not establish changes in thickness, wildlife impacts or a long-term trend.",
  "mapHref": "#extent-title",
  "mapLabel": "Explore the sea-ice record",
  "methodsHref": "/data.html#polar-records",
  "source": "NOAA/NSIDC Sea Ice Index, Version 4",
  "sourceUrl": "https://nsidc.org/data/g02135/versions/4",
  "evidence": {
    "extentMillionKm2": 16.706,
    "date": "2026-10-06",
    "sameDayMean": 18.44275,
    "sampleStandardDeviation": 0.3840741272009677,
    "referenceYears": 28,
    "rangeLower": 17.674601745598064,
    "rangeUpper": 19.210898254401936,
    "rangePosition": "below",
    "differencePercent": -9.416979571918505,
    "dailySource": "https://noaadata.apps.nsidc.org/NOAA/G02135/south/daily/data/S_seaice_extent_daily_v4.0.csv",
    "citedMap": "/briefings/evidence/2026-10-08-antarctic-extent.png",
    "retrievedAt": "2026-10-07T16:01:57.835584+00:00"
  },
  "selectionReason": "First editorial example: latest saved hemisphere-wide extent and its existing same-calendar-day comparison.",
  "method": {
    "baseline": "1981\u20132010",
    "method": "Calendar-day mean \u00b1 two sample standard deviations; missing records excluded",
    "limitations": [
      "One daily reading does not establish a long-term trend or a record minimum.",
      "Mean \u00b1 two sample standard deviations describes the reference period; it is not a probability or confidence interval.",
      "Extent is a satellite-derived estimate at the 15% concentration threshold, separate from the OSI SAF map product.",
      "Recent daily values may be revised."
    ]
  },
  "sourceSha256": {
    "polar-data.json": "465697773926b1997e70071e97ebd042235fa118d3271d48572f5ba27b6a3381",
    "sea-ice-comparison.json": "4c5f42d866b874db8d10d94163ddaa88fe582fa967b2582b677ce839db9b0326"
  },
  "editorialAssessment": {
    "analyse": "Antarctic sea-ice extent was 16.706 million km\u00b2 on 6 October 2026, 9.4% below the same-calendar-day 1981\u20132010 mean.",
    "evaluate": "The central estimate is below the descriptive mean plus/minus two sample-standard-deviation range based on 28 valid years. This is not a record-low or probability claim. No source uncertainty interval is available in the saved daily record; recent values may be revised.",
    "explain": "The comparison identifies reduced seasonal sea-ice coverage relative to the reference period. It does not establish ice thickness, wildlife impacts or a long-term trend, and it is separate from land-ice loss."
  },
  "reviewedAt": "2026-10-08",
  "archivedInputs": "/briefings/evidence/2026-10-08-antarctic-inputs.json",
  "archivedInputsSha256": "d990ee8b3a42600c40f0dd5b5d50a3186ce8bbbdd08bca14a927eb3e54e8d435"
}