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Ian Joughin

Senior Principal Engineer

Affiliate Professor, Earth and Space Sciences






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


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

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

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


2000-present and while at APL-UW

Elastic stress coupling between supraglacial lakes

Stevens, L.A., and 7 others including I. Joughin, "Elastic stress coupling between supraglacial lakes," J. Geophys. Res., 129, doi:10.1029/2023JF007481, 2024.

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10 May 2024

Supraglacial lakes have been observed to drain within hours of each other, leading to the hypothesis that stress transmission following one drainage may be sufficient to induce hydro-fracture-driven drainages of other nearby lakes. However, available observations characterizing drainage-induced stress perturbations have been insufficient to evaluate this hypothesis. Here, we use ice-sheet surface-displacement observations from a dense global positioning system array deployed in the Greenland Ice Sheet ablation zone to investigate elastic stress transmission between three neighboring supraglacial lake basins. We find that drainage of a central lake can place neighboring basins in either tensional or compressional stress relative to their hydro-fracture scarp orientations, either promoting or inhibiting hydro-fracture initiation beneath those lakes. For two lakes located within our array that drain close in time, we identify tensional surface stresses caused by ice-sheet uplift due to basal-cavity opening as the physical explanation for these lakes' temporally clustered hydro-fracture-driven drainages and frequent triggering behavior. However, lake-drainage-induced stresses in the up-flowline direction remain low beyond the margins of the drained lakes. This short stress-coupling length scale is consistent with idealized lake-drainage scenarios for a range of lake volumes and ice-sheet thicknesses. Thus, on elastic timescales, our observations and idealized-model results support a stress-transmission hypothesis for inducing hydro-fracture-driven drainage of lakes located within the region of basal cavity opening produced by the initial drainage, but refute this hypothesis for distal lakes.

Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020

Otosaka, I.N., and 67 others including I. Joughin, M.D. King, B.E. Smith, and T.C. Sutterley, "Mass balance of the Greenland and Antarctic ice sheets from 1992 to 2020," Earth Syst. Sci. Data, 15, 1297-1616, doi:10.5194/essd-15-1597-2023, 2023.

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20 Apr 2023

Ice losses from the Greenland and Antarctic ice sheets have accelerated since the 1990s, accounting for a significant increase in the global mean sea level. Here, we present a new 29-year record of ice sheet mass balance from 1992 to 2020 from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE). We compare and combine 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field. Between 1992 and 2020, the ice sheets contributed 21.0±1.9 mm to global mean sea level, with the rate of mass loss rising from 105 Gt yr−1 between 1992 and 1996 to 372 Gt yr−1 between 2016 and 2020. In Greenland, the rate of mass loss is 169±9 Gt yr−1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86 Gt yr−1 in 2017 to 444 Gt yr−1 in 2019 due to large variability in surface mass balance. In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9 Gt yr−1) and, to a lesser extent, from the Antarctic Peninsula (13±5 Gt yr−1). East Antarctica remains close to a state of balance, with a small gain of 3±15 Gt yr−1, but is the most uncertain component of Antarctica's mass balance.

Weekly to monthly terminus variability of Greenland's marine-terminating outlet glaciers

Black, T.E., and I. Joughin, "Weekly to monthly terminus variability of Greenland's marine-terminating outlet glaciers," Cryosphere, 17, doi:10.5194/tc-17-1-2023, 2023.

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5 Jan 2023

Seasonal terminus-position variability of Greenland's marine-terminating outlet glaciers is superimposed on multidecadal trends of glacier retreat. To characterize this seasonal variability, we manually digitized terminus positions for 219 marine-terminating glaciers in Greenland from January 2015 through December 2021 using Sentinel-1 synthetic aperture radar (SAR) mosaics. We digitized at a monthly frequency for 199 glaciers and at a 6 d frequency for 20 glaciers. We found that nearly 80 % of glacier termini in Greenland vary significantly on a seasonal basis. For these seasonally varying glaciers, on average, seasonal retreat typically begins in mid-May, and seasonal advance generally commences in early October. The timing of the initiation of the retreat period may be related to the timing of the onset of ice-sheet surface melt. The rate of retreat events peaks in late summer and reaches a minimum in late winter and early spring. The median magnitude of terminus-position seasonality, the difference between glacier length at the dates of peak advance and retreat, is about 220 m. We find a stronger correlation between this magnitude and glacier velocity than between magnitude and glacier width. Terminus-position seasonality can influence longer-term glacier dynamics and, consequently, ice-sheet mass balance. This study contributes to our understanding of terminus-position seasonality for individual glaciers and collectively for glaciers around the entire Greenland Ice Sheet.

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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

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