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Harry Stern

Principal Mathematician






Harry Stern studies Arctic sea ice and climate using satellite data. Current interests include the changing sea ice habitat of polar bears and narwhals, and the history of Arctic exploration. He participated in the Around the Americas expedition, sailing through the eastern half of the Northwest Passage in 2009. He served as an Associate Editor for the Journal of Geophysical Research%u2013Oceans (2007-2010). He helped to launch the annual Polar Science Weekend at Seattle%u2019s Pacific Science Center, and now runs the event. He has a B.S. in mathematics and M.S. in applied mathematics. He has been with the Polar Science Center since 1987 and with the University since 1980.

Department Affiliation

Polar Science Center


B.S. Mathematics, Stanford University, 1980

M.S. Applied Mathematics, University of Washington, 1982


Polar Science Weekend @ Pacific Science Center

This annual event at the Pacific Science Center shares polar science with thousands of visitors. APL-UW researchers inspire appreciation and interest in polar science through dozens of live demonstrations and hands-on activities.

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10 Mar 2017

Polar research and technology were presented to thousands of visitors by APL-UW staff during the Polar Science Weekend at Seattle's Pacific Science Center. The goal of is to inspire an appreciation and interest in science through one-on-one, face-to-face interactions between visitors and scientists. Guided by their 'polar passports', over 10,000 visitors learned about the Greenland ice sheet, the diving behavior of narwhals, the difference between sea ice and freshwater ice, how Seagliders work, and much more as they visited dozens of live demonstrations and activities.

The Polar Science Weekend has grown from an annual outreach event to an educational research project funded by NASA, and has become a model for similar activities hosted by the Pacific Science Center. A new program trains scientists and volunteers how to interact with the public and how to design engaging exhibits.

A Look Back to Arctic Climate in the 18th Century

Captain James Cook’s logs and maps give insight to late-18th century sea ice conditions north of Bering Strait.

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15 Nov 2016

Polar Science Center mathematician Harry Stern used these records to plot the sea ice edge that Cook encountered in 1778. These earliest records of summer ice extent in the Chukchi Sea underscore the dramatic recent changes in arctic climate.

Focus on Arctic Sea Ice: Current and Future States of a Diminished Sea Ice Cover

APL-UW polar scientists are featured in the March edition of the UW TV news magazine UW|360, where they discuss their research on the current and future states of a diminished sea ice cover in the Arctic.

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7 Mar 2012

The dramatic melting of Arctic sea ice over the past several summers has generated great interest and concern in the scientific community and among the public. Here, APL-UW polar scientists present their research on the current state of Arctic sea ice. A long-term, downward trend in sea ice volume is clear.

They also describe how the many observations they gather are used to improve computer simulations of global climate that, in turn, help us to asses the impacts of a future state of diminished sea ice cover in the Arctic.

This movie presentation was first seen on the March 2012 edition of UW|360, the monthly University of Washington Television news magazine.


2000-present and while at APL-UW

Reconstructing variability in West Greenland ocean biogeochemistry and bowhead whale (Balaena mysticetus) food web structure using amino acid isotope ratios

Pomerleau, C., M.P. Heide-Jørgensen, S.H. Ferguson, H.L. Stern, J.L. Høyer, and G.A. Stern, "Reconstructing variability in West Greenland ocean biogeochemistry and bowhead whale (Balaena mysticetus) food web structure using amino acid isotope ratios," Polar Biol., EOR, doi:10.1007/s00300-017-2136-x, 2017.

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9 Jun 2017

Climate change is causing physical and biological changes in the polar marine environment, which may impact higher trophic level predators such as the bowhead whale (Balaena mysticetus) and the structure of their food webs. We used bulk stable isotope analysis and compound-specific isotope analysis (CSIA) of individual amino acids (AA) to examine bowhead whale trophic position and the biogeochemistry of one of their feeding grounds, Disko Bay, West Greenland, over a period of 7 years (2007–2013). We also examined whether environmental conditions such as sea ice concentration and sea surface temperature were causing any interannual variation in isotope data. Bulk δ15N values were consistent across the 7 years of sampling and were similar between sex classes. Bulk δ13C and essential-AAs δ13C values displayed an overall temporal decline of 1.0 and 1.4%, respectively. A significant positive linear relationship was found between δ13C of bulk skin and essential-AAs suggesting that some of the observed isotopic variation in bowhead whales between years reflect changes in the carbon at the base of the food web. There were no correlations between the δ13C and δ15N values of isotopic tracers with sea ice concentrations or sea surface temperatures. The trophic level of bowhead whales remained stable over time despite large interannual variability in ice and temperature regimes. Our results indicate that the recent environmental changes in West Greenland resulted in no trophic perturbation being transferred to bowhead whales during that time period. Our study shows that the novel approach of CSIA-AA can be used effectively to study the combined temporal variation of bowhead whale food web structure and ecosystem isotopic baseline values and detect changes at the species and ecosystem levels.

Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation

Hauser, D.D.W., K.L. Laidre, K.M. Stafford, H.L. Stern, R.S. Suydam, and P.R. Richard, "Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation," Global Clim. Change, 23, 2206-2217, doi:10.111/gcb.13564, 2017.

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1 Jun 2017

Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993–2002) and 'late' (2004–2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.

Rebuilding beluga stocks in West Greenland

Heide-Jørgensen, M.P., R.G. Hansen, S. Fossette, N.H. Nielsen, D.L. Borchers, H. Stern, and L. Witting, "Rebuilding beluga stocks in West Greenland," Anim. Conserv., 20, 282-293, doi:10.1111/acv.12315, 2017.

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1 Jun 2017

Decisions about sustainable exploitation levels of marine resources are often based on inadequate data, but are nevertheless required for practical purposes. We describe one exception where abundance estimates spanning 30 years and catch data spanning more than 40 years were used in a Bayesian assessment model of belugas Delphinapterus leucas off West Greenland. The model was updated with data from a visual aerial survey on the wintering ground in 2012. Methods that take account of stochastic animal availability by using independent estimates of forward and perpendicular sighting distances were used to estimate beluga abundance. A model that appears to be robust to the presence of a few large groups yielded an estimate of 7456 belugas (cv = 0.44), similar to a conventional distance-sampling estimate. A mark–recapture distance analysis that corrects for perception and availability bias estimated the abundance to be 9072 whales (cv = 0.32). Increasing distance of beluga sightings from shore was correlated with decreasing sea ice cover, suggesting that belugas expand their distribution offshore (i.e. westward in this context) with the reduction of coastal sea ice. A model with high (0.98) adult survival estimated a decline from 18 600 (90% CI: 13 400, 26 000) whales in 1970 to 8000 (90% CI: 5830, 11 200) in 2004. The decline was probably a result of a period with exceptionally large catches. Following the introduction of catch limits in 2004, the model projects an increase to 11 600 (90% CI: 6760, 17 600) individuals in 2020 (assuming annual removals of 294 belugas after 2014). If the annual removal level is fixed at 300 individuals, a low-survival (0.97) model predicts a 75% probability of an increasing population during 2015–2020. Reduced removal rates due to catch limits and the more offshore, less accessible distribution of the whales are believed to be responsible for the initial signs of population recovery.

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In The News

How to conserve polar bears — and maintain subsistence harvest — under climate change

UW News and Information, Hannah Hickey

Polar bears are listed as a threatened species as the ice-covered ocean they depend on for hunting and transportation becomes scarce.

15 Mar 2017

Polar Science Weekend attractions range from old-fashioned ice sled to future NASA satellite

UW News and Information, Hannah Hickey

University of Washington polar scientists are holding the 12th annual Polar Science Weekend, Friday through Sunday, March 3-5, at Pacific Science Center in Seattle.

1 Mar 2017

Seattle climate scientists spread word on warming, skip politics

The Seattle Times, Jerry Large

Climate scientists at the University of Washington want to talk more about their work because it and public policy are intertwined. They stick to the science side of the equation, which they want the rest of us to understand better so that we can make informed decisions about climate change.

12 Jan 2017

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