PenguinTracker / Glaciers / Institute Ice Stream

Institute Ice Stream

Outlet glacier · no detectable change · measured 2002–2022

Institute Ice Stream is showing no detectable change in speed. Speed across 1,267 km² of grounded ice averaged 352 m/yr in 2022 — 1.0 metres a day — measured from satellite feature tracking over 12 usable years.

Measured speed by year (blue). The dashed line is the least-squares fit across every usable year — not significant at twice its standard error. Years whose coverage of the measured pixel set fell below 90% are dropped rather than interpolated, because feature tracking succeeds preferentially on fast crevassed ice and a sparse year is biased fast.

Measured domaingrounded ice

Measured trunk1,267 km²

Years used12 of 24 in the archive

Period2002 – 2022

Speed in 2002341 m/yr

Speed in 2022352 m/yr

Fitted change-0.2%

Fitted trend-0.0 m/yr² ± 0.8

Significancenot significant — slope is 0.0× its standard error

Mean coverage99% of the measured pixel set

Position81°30'S 75°00'W

What this number is, and is not

This is the speed of the ice surface, averaged over a fixed set of trunk pixels that carry valid data in every year reported. It is measured on grounded ice only. Grounded ice and floating shelf are separated using the masks the ITS_LIVE files carry, because they mean different things: grounded ice speeding up puts more ice across the grounding line, while a shelf that is already afloat displaces no extra water however fast it moves — and shelf speed jumps after a calving. The fitted change is quoted rather than the endpoint change (+3.2%), because an endpoint figure rides on two single noisy years.

Coverage before 1999 is negligible and no continent-wide acceleration figure is defensible from this product. Per-glacier series are only reported where the coverage gate is met. Each box is a fixed window around the trunk, not a drainage basin, so these are speeds over a measured area and not mass-balance figures.