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Ian Joughin

Senior Principal Engineer

Affiliate Professor, Earth and Space Sciences

Email

irj@uw.edu

Phone

206-221-3177

Biosketch

Ian Joughin continues his pioneering research into the use of differential SAR interferometry for the estimation of surface motion and topography of ice sheets. He combines the remote sensing with field work and modeling to solve ice dynamics problems. Solving the problems helps him understand the mass balance of the Greenland and Antarctic Ice Sheets in response to climate change.

In addition to polar research, he also contributed to the development of algorithms that were used to mosaic data for the near-global map of topography from the Shuttle Radar Topography Mission (SRTM).

Department Affiliation

Polar Science Center

Education

B.S. Electrical Engineering, University of Vermont, 1986

M.S. Electrical Engineering, University of Vermont, 1990

Ph.D. Electrical Engineering, University of Washington, 1995

Publications

2000-present and while at APL-UW

Inland migration of near-surface crevasses in the Amundsen Sea Sector, West Antarctica

Hoffman, A.O., and 7 others including I. Joughin, "Inland migration of near-surface crevasses in the Amundsen Sea Sector, West Antarctica," Cryosphere, 19, 1353-1372, doi:10.5194/tc-19-1353-2025, 2025.

More Info

26 Mar 2025

Since distributed satellite observations of elevation change and velocity became available in the 1990s, Thwaites, Pine Island, Haynes, Pope and Kohler glaciers, located in Antarctica's Amundsen Sea Sector, have thinned and accelerated in response to ocean-induced melting and grounding-line retreat. We develop a crevasse image segmentation algorithm to identify and map surface crevasses on the grounded portions of these glaciers between 2015 and 2022 using Sentinel-1A satellite synthetic aperture radar (SAR) imagery. We also advance a geometric model for firn tensile strength dependent on porosity and the tensile strength of ice. On Pine Island and Thwaites glaciers, which have both accelerated since 2015, crevassing has expanded tens of kilometers upstream of the 2015 extent. From the crevasse time series, we find that crevassing is strongly linked to principal surface stresses and consistent with von Mises fracture theory predictions. Our geometric model, analysis of SAR and optical imagery, and ice-penetrating radar data suggest that these crevasses are near-surface features restricted to the firn. The porosity dependence of the near-surface tensile strength of the ice sheet may explain discrepancies between the tensile strength inferred from remotely sensed surface crevasse observations and tensile strength measured in laboratory experiments, which often focus on ice (rather than firn) fracture. The near-surface nature of these features suggests that the expansion of crevasses inland has a limited direct impact on glacier mechanics.

Thwaites Glacier thins and retreats fastest where ice-shelf channels intersect its grounding zone

Chartrand, A.M., I.M. Howat, I.R. Joughin, and B.E. Smith, "Thwaites Glacier thins and retreats fastest where ice-shelf channels intersect its grounding zone," Cryosphere, 18, 4971-4992, doi:10.5194/tc-18-4971-2024, 2024.

More Info

6 Nov 2024

Antarctic ice shelves buttress the flow of the ice sheet but are vulnerable to increased basal melting from contact with a warming ocean and increased mass loss from calving due to changing flow patterns. Channels and similar features at the bases of ice shelves have been linked to enhanced basal melting and observed to intersect the grounding zone, where the greatest melt rates are often observed. The ice shelf of Thwaites Glacier is especially vulnerable to basal melt and grounding zone retreat because the glacier has a retrograde bed leading to a deep trough below the grounded ice sheet. We use digital surface models from 2010–2022 to investigate the evolution of its ice-shelf channels, grounding zone position, and the interactions between them. We find that the highest sustained rates of grounding zone retreat (up to 0.7 km yr-1) are associated with high basal melt rates (up to ~250 m yr-1) and are found where ice-shelf channels intersect the grounding zone, especially atop steep local retrograde slopes where subglacial channel discharge is expected. We find no areas with sustained grounding zone advance, although some secular retreat was distal from ice-shelf channels. Pinpointing other locations with similar risk factors could focus assessments of vulnerability to grounding zone retreat.

Characterizing southeast Greenland fjord surface ice and freshwater flux to support biological applications

Moon, T.A., B. Cohen, T.E. Black, K.L. Laidre, H.L. Stern, and I. Joughin, "Characterizing southeast Greenland fjord surface ice and freshwater flux to support biological applications," Cryosphere, 18, 4845-4872, doi:10.5194/tc-18-4845-2024, 2024.

More Info

29 Oct 2024

Southeast Greenland (SEG) is characterized by complex morphology and environmental processes that create dynamic habitats for top marine predators. Active glaciers producing solid-ice discharge, freshwater flux, offshore sea ice transport, and seasonal landfast-ice formation all contribute to a variable, transient environment within SEG fjord systems. Here, we investigate a selection of physical processes in SEG to provide a regional characterization that reveals physical system processes and supports biological research. SEG fjords exhibit high fjord-to-fjord variability regarding bathymetry, size, shape, and glacial setting, influencing some processes more than others. For example, during fall, the timing of offshore sea ice formation near SEG fjords progresses temporally when moving southward across latitudes, while the timing of offshore sea ice disappearance is less dependent on latitude. The rates of annual freshwater flux into fjords, however, are highly variable across SEG, with annual average input values ranging from ~1 x 108 to ~1.25 x 1010 m3 (~0.1–12.5 Gt) for individual fjords. Similarly, the rates of solid-ice discharge in SEG fjords vary widely — partly due to the irregular distribution of active glaciers across the study area (60–70°N). Landfast sea ice, assessed for eight focus fjords, is seasonal and has a spatial distribution highly dependent on individual fjord topography. Conversely, glacial ice is deposited into fjord systems year-round, with the spatial distribution of glacier-derived ice depending on the location of glacier termini. As climate change continues to affect SEG, the evolution of these metrics will vary individually in their response, and next steps should include moving from characterization to system projection. Due to the projected regional ice sheet persistence that will continue to feed glacial ice into fjords, it is possible that SEG could remain a long-term refugium for polar bears and other ice-dependent species on a centennial to millennial scale, demonstrating a need for continued research into the SEG physical environment.

More Publications

In The News

UW polar bear expert appears in BBC-produced film about the Arctic

UW News, Hannah Hickey

A new production, "Arctic: Our Frozen Planet," narrated by Benedict Cumberbatch, screens May 25 and 27 at the Pacific Science Center in Seattle. Eric Regehr, a researcher at the UW Applied Physics Laboratory, appears in the film doing fieldwork on Wrangel Island, an island off the northeast coast of Russia that is home to the world’s highest concentration of polar bears.

23 May 2023

Parts of Greenland Warmer Now Than in 1,000 Years

Axios, Andrew Freedman

The new research offers the first conclusive evidence of human-induced long-term warming and increased meltwater runoff in the northern and central parts of Greenland, typically the coldest parts of the ice sheet. Ian Joughin comments that the warming has a clear linear trend, which will likely steepen with time.

19 Jan 2023

Here are 3 dangerous climate tipping points the world is on track for

NPR, Rebecca Hersher and Lauren Sommer

Climate tipping points won't be as abrupt as that term would suggest. Most will unfold over the course of decades. Some could take centuries. Some may be partially reversible or avoidable. But they all have enormous and lasting implications for the humans, plants and animals on Earth.

10 Nov 2022

More News Items

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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