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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—Oceans (2007–2010). He helped to launch the annual Polar Science Weekend at Seattle's 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

Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions

Laidre, K.L. and 18 others including E.V. Regehr, B. Cohen, and H.L. Stern, "Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions," Science, 376, 1333-1338, doi:10.1126/science.abk2793, 2022.

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17 Jun 2022

Polar bears are susceptible to climate warming because of their dependence on sea ice, which is declining rapidly. We present the first evidence for a genetically distinct and functionally isolated group of polar bears in Southeast Greenland. These bears occupy sea-ice conditions resembling those projected for the High Arctic in the late 21st century, with an annual ice-free period that is >100 days longer than the estimated fasting threshold for the species. Whereas polar bears in most of the Arctic depend on annual sea ice to catch seals, Southeast Greenland bears have a year-round hunting platform in the form of freshwater glacial mélange. This suggests that marine-terminating glaciers, although of limited availability, may serve as previously unrecognized climate refugia. Conservation of Southeast Greenland polar bears, which meet criteria for recognition as the world’s 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.

Float your boat launching students into the Arctic Ocean

Forcucci, D., I. Rigor, W. Ermold, and H. Stern, "Float your boat launching students into the Arctic Ocean," Oceanography, 35, doi:10.5670/oceanog.2022.102, 2022.

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1 Jun 2022

Our understanding of Arctic sea ice and ocean circulation began with the drift of two wooden boats. Following the legacy of the early Arctic explorers, Float Your Boat (FYB) is a unique and fun outreach program that provides a novel opportunity for students and the public to learn about the Arctic Ocean. Participants decorate toy wooden boats with words and art, and the boats are deployed on Arctic Ocean ice floes by icebreakers. Personal connections to the Arctic develop with the anticipation and excitement of the boats being reported on distant shores years later by beachcombers.

A novel mark-recapture-recovery survey using genetic sampling for polar bears Ursus maritimus in Baffin Bay

Atkinson, S.N., K.L. Laidre, T.W. Arnold, S. Stapleton, E.V. Regehr, E.W. Born, Ø. Wiig, M. Dyck, N.J. Lunn, H.L. Stern, and D. Paetkau, "A novel mark-recapture-recovery survey using genetic sampling for polar bears Ursus maritimus in Baffin Bay," Endanger. Species Res., 46, 105-120, doi:10.3354/esr01148, 2021.

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7 Oct 2021

Changes in sea-ice dynamics are affecting polar bears Ursus maritimus across their circumpolar range, which highlights the importance of periodic demographic assessments to inform management and conservation. We used genetic mark-recapture-recovery to derive estimates of abundance and survival for the Baffin Bay (BB) polar bear subpopulation — the first time this method has been used successfully for this species. Genetic data from tissue samples we collected via biopsy darting were combined with historical physical capture and harvest recovery data. The combined data set consisted of 1410 genetic samples (2011–2013), 914 physical captures (1993–1995, 1997), and 234 harvest returns of marked bears (1993–2013). The estimate of mean subpopulation abundance was 2826 (95% CI = 2284–3367) in 2012–2013. Estimates of annual survival (mean ñ SE) were 0.90 ñ 0.05 and 0.78 ñ 0.06 for females and males age >= 2 yr, respectively. The proportion of total mortality of adult females and males that was attributed to legal harvest was 0.16 ñ 0.05 and 0.26 ñ 0.06, respectively. Remote sensing sea-ice data, telemetry data, and spatial distribution of onshore sampling indicated that polar bears were more likely to use offshore sea-ice habitat during the 1990s sampling period compared to the 2010s. Furthermore, in the 1990s, sampling of deep fjords and inland areas was limited, and no offshore sampling occurred in either time period, which precluded comparisons of abundance between the 1993–1997 and 2011–2013 study periods. Our findings demonstrate that genetic sampling can be a practical method for demographic assessment of polar bears over large spatial and temporal scales.

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In The News

Arctic ice has seen an 'irreversible' thinning since 2007, study says

Washington Post, Scott Dance

New research suggests the decline was a fundamental change unlikely to be reversed this century — perhaps proof that the planet has passed an alarming climactic tipping point. Mathematician Harry Stern offers a counterpoint.

15 Mar 2023

'Wholly unexpected': These polar bears can survive with less sea ice

The New York Times, Henry Fountain

The overall threat to the animals from climate change remains, but a new finding suggests that small numbers might survive for longer as the Arctic warms. See related articles on the UW News pinboard.

16 Jun 2022

Newly documented population of polar bears in Southeast Greenland sheds light on the species' future in a warming Arctic

UW News, Hannah Hickey

Scientists have documented a previously unknown subpopulation of polar bears living in Southeast Greenland. The polar bears survive with limited access to sea ice by hunting from freshwater ice that pours into the ocean from Greenland’s glaciers.

16 Jun 2022

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