Cape Denison
Cape Denison is a known penguin breeding site in the Victoria Land, at 67°00'S 142°40'E. Adélie penguins have been recorded here.
Species recorded here
The sea around this site, 1979–2024
Averaged over the 22 ocean cells within 100 km, this site carries sea ice for a median of 284 days a year, peaking at a median 95.1% concentration. The ice season here is lengthening at +17.4 ± 7.6 days per decade, and that survives every gate this archive applies.
15 other known breeding sites lie within 200 km of this one, and the cells this measurement averages over reach 100 km — so this record and theirs are not independent readings of the sea. Thinned so that no two overlap, the 728 measurable sites in this archive become 56 places.
In the 2023 ice year — the last one this archive holds — the sea ice here lasted 322 days, which is this site's 29th shortest season of 41 and above its own median of 284. It was below the median at 657 of the 728 sites measured here and at 44 of the 56 independent places, which is the most widespread short season in the record: the whole archive is drawn in one frame.
This is one of the ten sites the 2010 iceberg event was found at. Scored blind on the change in summer sea ice from the 2001–10 ice years to the 2011–20 ones, it ranks 1st of 728: 4.0% before and 53.5% after, 9.2 times its own year-to-year spread. No summer trend is published here — a straight line is not a description of a series with a step in it — and the fuller story is on 729 sites, 56 places.
Two limits. This is the sea around the site and never the fast ice on it — at 25 km that is invisible. And the archive ends 2024-12-31, so it is a climate record rather than a current reading.
Asked whether this is a trend or a step
Every fitted series on this site was made to nominate its own worst break year against a Monte Carlo null, with no event supplied. 3 of the figures published for this site came back flagged: the strongest is ice-season length · 1979–2024, which breaks at 2010 — December 2010, when the iceberg B09B grounded in Commonwealth Bay. At 3 of them the fitted direction reverses once the step is allowed for, so the published slope is not a description of this record.
| Measurement | Break | Plain | With one step | Step | Verdict |
|---|---|---|---|---|---|
| ice-season length · 1979–2024 | 2010 | +17.41 | -8.13 | +85.17 ± 19.70 | sign reverses |
| ice-season length · 1988 onward | 2010 | +26.97 | -4.65 | +79.78 ± 22.71 | sign reverses |
| annual mean sea ice · 1979–2024 | 2010 | +3.76 | -0.41 | +13.92 ± 4.90 | sign reverses |
Slopes are per decade — points of concentration for the sea-ice windows, days for the dates and season lengths. How every series on this site was asked →
Why there is no count on this page
Penguins are too small to resolve from orbit. What is visible is the guano stain a colony leaves on the ice, which is why counting from satellite is a colour problem rather than a counting problem — and it is not solved. Our own detector correlates at r = −0.16 against ground counts across eight colonies, which is no relationship at all. Until that is fixed, this site publishes locations and says nothing about numbers. A number we cannot defend would be worse than none.