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Harry Stern

Principal Mathematician

Email

harry@apl.washington.edu

Phone

206-543-7253

Biosketch

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

Education

B.S. Mathematics, Stanford University, 1980

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

Videos

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.

Publications

2000-present and while at APL-UW

Interrelated ecological impacts of climate change on an apex predator

Laidre, K.L., S. Atkinson, E.V. Regehr, H.L. Stern, E.W. Born, Ø. Wiig, N.J. Lunn, and M. Dyck, "Interrelated ecological impacts of climate change on an apex predator," Ecol. Appl., EOR, doi:10.1002/eap.2071, 2020.

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10 Jan 2020

Climate change has broad ecological implications for species that rely on sensitive habitats. For some top predators, loss of habitat is expected to lead to cascading behavioral, nutritional, and reproductive changes that ultimately accelerate population declines. In the case of the polar bear (Ursus maritimus), declining Arctic sea ice reduces access to prey and lengthens seasonal fasting periods. We used a novel combination of physical capture, biopsy darting, and visual aerial observation data to project reproductive performance for polar bears by linking sea ice loss to changes in habitat use, body condition (i.e., fatness), and cub production. Satellite telemetry data from 43 (1991–1997) and 38 (2009–2015) adult female polar bears in the Baffin Bay subpopulation showed that bears now spend an additional 30 d on land (90 d in total) in the 2000s compared to the 1990s, a change closely correlated with changes in spring sea ice breakup and fall sea ice formation. Body condition declined for all sex, age, and reproductive classes and was positively correlated with sea ice availability in the current and previous year. Furthermore, cub litter size was positively correlated with maternal condition and spring breakup date (i.e., later breakup leading to larger litters), and negatively correlated with the duration of the ice‐free period (i.e., longer ice‐free periods leading to smaller litters). Based on these relationships, we projected reproductive performance three polar bear generations into the future (approximately 35 yr). Results indicate that two‐cub litters, previously the norm, could largely disappear from Baffin Bay as sea ice loss continues. Our findings demonstrate how concurrent analysis of multiple data types collected over long periods from polar bears can provide a mechanistic understanding of the ecological implications of climate change. This information is needed for long‐term conservation planning, which includes quantitative harvest risk assessments that incorporate estimated or assumed trends in future environmental carrying capacity.

Vulnerability of arctic marine mammals to vessel traffic in the increasingly ice-free Northwest Passage and Northern Sea Route

Hauser, D.D.W., K.L. Laidre, and H.L. Stern, "Vulnerability of arctic marine mammals to vessel traffic in the increasingly ice-free Northwest Passage and Northern Sea Route," Proc. Nat. Acad. Sci. USA, 115, 7617-7622, doi:10.1073/pnas.1803543115, 2018

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2 Jul 2018

The fabled Northwest Passage and Northern Sea Route that were once the quests of early Western explorers are now increasingly sea ice–free, with routine vessel transits expected by midcentury. The potential impacts of this novel vessel traffic on endemic Arctic marine mammal (AMM) species are unknown despite their critical social and ecological roles in the ecosystem and widely recognized susceptibility to ice loss. We developed a vulnerability assessment of 80 subpopulations of seven AMM species to vessel traffic during the ice-free season. Vulnerability scores were based on the combined influence of spatially explicit exposure to the sea routes and a suite of sensitivity variables. More than half of AMM subpopulations (42/80) are exposed to open-water vessel transits in the Arctic sea routes. Narwhals (Monodon monoceros) were estimated to be most vulnerable to vessel impacts, given their high exposure and sensitivity, and polar bears (Ursus maritimus) were estimated to be the least vulnerable because of their low exposure and sensitivity. Regions with geographic bottlenecks, such as the Bering Strait and eastern Canadian Arctic, were characterized by two to three times higher vulnerability than more remote regions. These pinch points are obligatory pathways for both vessels and migratory AMMs, and so represent potentially high conflict areas but also opportunities for conservation-informed planning. Some of the species and regions identified as least vulnerable were also characterized by high uncertainty, highlighting additional data and monitoring needs. Our quantification of the heterogeneity of risk across AMM species provides a necessary first step toward developing best practices for maritime industries poised to advance into this rapidly changing seascape.

Indirect effects of sea ice loss on summer–fall habitat and behaviour for sympatric populations of an Arctic marine predator

Hauser, D.D.W., K.L. Laidre, H.L. Stern, R.S. Suydam, and P.R. Richard, "Indirect effects of sea ice loss on summer–fall habitat and behaviour for sympatric populations of an Arctic marine predator," Divers. Distrib., 24, 791-799, doi:10.1111/ddi.12722, 2018.

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1 Jun 2018

Climate change is fundamentally altering habitats, with complex consequences for species across the globe. The Arctic has warmed 2–3 times faster than the global average, and unprecedented sea ice loss can have multiple outcomes for ice‐associated marine predators. Our goal was to assess impacts of sea ice loss on population‐specific habitat and behaviour of a migratory Arctic cetacean.

Using satellite telemetry data collected during summer–fall from sympatric beluga whale (Delphinapterus leucas) populations ("Chukchi" and "Beaufort" belugas), we applied generalized estimating equations to evaluate shifts in sea ice habitat associations and diving behaviour during two periods: 1993–2002 ("early") and 2004–2012 ("late"). We used resource selection functions to assess changes in sea ice selection as well as predict trends in habitat selection and "optimal" habitat, based on satellite‐derived sea ice data from 1990 to 2014.

Sea ice cover declined substantially between periods, and Chukchi belugas specifically used significantly lower sea ice concentrations during the late than early period. Use of bathymetric features did not change between periods for either population. Population‐specific sea ice selection, predicted habitat and the amount of optimal habitat also generally did not change during 1990–2014. Chukchi belugas tracked during 2007–2012 made significantly more long‐duration and deeper dives than those tracked during 1998–2002.

Taken together, our results suggest bathymetric parameters are consistent predictors of summer–fall beluga habitat rather than selection for specific sea ice conditions during recent sea ice loss. Beluga whales were able to mediate habitat change despite their sea ice associations. However, trends towards prolonged and deeper diving possibly indicate shifting foraging opportunities associated with ecological changes that occur in concert with sea ice loss. Our results highlight that responses by some Arctic marine wildlife can be indirect and variable among populations, which could be included in predictions for the future.

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In The News

Polar bears are getting thinner and having fewer cubs

CNN, Scottie Andrew

The impact of the climate crisis is becoming more and more obvious to humans and their animal neighbors. But among all species, polar bears might be some of the hardest hit.

14 Feb 2020

Polar bears in Baffin Bay skinnier, having fewer cubs due to less sea ice

UW News, Hannah Hickey

Polar bears are spending more time on land than they did in the 1990s due to reduced sea ice, new University of Washington-led research shows. Bears in Baffin Bay are getting thinner and adult females are having fewer cubs than when sea ice was more available.

12 Feb 2020

Polar bears struggle as sea ice declines

NASA Earth Observatory, Kasha Patel

A new study shows that polar bears are spending less time on sea ice, leading them to fast longer, become thinner and have fewer cubs.

4 Feb 2020

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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