Arctic Ice Wedges Held Steady for a Decade, Despite Record Warmth

The National Park Service's Arctic Inventory and Monitoring Network (ARCN) tracks permafrost in the five park units of northern Alaska, using ground-temperature stations and satellite and aerial images of permafrost landforms.

An aerial photograph from our Bering Land Bridge National Preserve study area with numerous ice-wedge polygons. NPS/Matt Nolan.

The Park Service's Arctic Inventory & Monitoring Network parks. National Park Service

Ice wedges

Ice wedges are masses of nearly pure ice just below the surface, and they create much of the Arctic's distinctive polygon-patterned ground. Because they thaw easily, they can give early warning of permafrost loss — and when they melt, they open new ponds and drainage paths that can empty lakes quickly.

Ecologist Dave Swanson re-examined ice wedges in three study areas: in Bering Land Bridge National Preserve, Kobuk Valley National Park and Noatak National Preserve. When ice wedges melt, ponds form around the edges of the polygons, so mapping ponds in aerial and satellite images shows where wedges are degrading.

What he found

• Satellite images from 2019 and 2020 showed little new sinking from melting ice wedges since the previous images, from 2006–2009.
• That was a surprise, given record warm temperatures in 2014–2019 and major ice-wedge loss in the earlier interval (from the early 1950s to 2006–2009, in Kobuk Valley).
• Old damage lingers: small ponds from earlier melting keep linking up into new drainage channels, which can drain lakes rapidly.

Most ice wedges between these lakes in Noatak National Preserve changed little from 2007 to 2019 — but pits and ponds from earlier melting gave this lake a path to drain once it grew around the higher ground to its west. Image from the National Park Service's page on the study

Elongated ponds, about 3 feet wide, formed over degraded ice wedges in the Kobuk Valley study area. NPS/Dave Swanson

What it means

• Good news: ice-wedge loss seen before 2009, and its effects on the landscape, seem to have slowed for now.
• It matches a recent ARCN study that found few permafrost-thaw landslides in recent years despite the heat.
• But local effects can be dramatic, as old pits join into channels that drain lakes.
• Monitoring will continue in case climate change or unusual weather pushes ice wedges past a threshold into instability again.

More: the full NPS report on ice wedges · recent warming in the region · permafrost-thaw landslides · video: Ice Wedges in Alaska's National Parks.

Sources

Based on "Ice Wedges Surprisingly Stable over the Past Decade," a 2022 permafrost monitoring brief of the Arctic Inventory and Monitoring Network, National Park Service; a work of the United States government in the public domain. An aerial photograph credited to the NPS and Matt Nolan jointly is not reproduced. Pictures an earlier version of this page left out were restored on 2026-09-26.