Polar Bears International (PBI) is a non-profit organization dedicated to the conservation of polar bears, with a focus on saving their sea ice habitat through climate action. You can read more about them here: https://polarbearsinternational.org
Flavio has been volunteering with PBI since 2016 and since 2022 is acting as their Chief Climate Scientist, together with a great team.
Our work with PBI includes:
- Advising on the latest climate science and how it might affect conservation work and communication strategies.
- Contributing to PBI’s educational webcasts for school classes and other audiences, often broadcasted live from a tundra buggy outside of Churchill, Canada, at the shores of Hudson Bay:
- Ice Bears in your backyard (video, 2016)
- STEM on the Tundra: Cool Jobs! (video, 2016)
- At the top of the world with Polar Bears (video, 2018)
- Life in the Arctic, top to bottom (video, 2018)
- The Future for Polar Bears (video, 2022)
- Pole to Pole Policy (video, 2023)
- Thaw & Freeze (GBH Forum network, video, 2024)
- Co-authoring book chapters and blog posts with other scientists (incl. Steven Amstrup) on how climate change affects the habitat of various species across the planet:
- Blog posts:
- From Tropical Islands to Polar Bears: Half a Degree in Warming Makes a Difference
- From Wildfire Smoke in New York to Polar Bears in Hudson Bay
- The Future of Arctic Sea Ice Revisited
- Sharing Climate Hope Over the Holidays (interview with Barbara Nielsen)
- Geoengineering – Good Idea? Bad Idea? Do We Need to Know?
- An Unusual Summer in Hudson Bay – What Does It Mean for Polar Bears? (co-authored with Joe Northrup)
- Book Chapters:
- Blog posts:
- Designing graphics that convey the magnitude of climate change based on instrumental data and climate model simulations:
Useful scientific figures for Hudson Bay climate
Length of ice-free season
The following figures show the annual sea ice break-up and freeze-up dates in Hudson Bay (Western and Southern Hudson Bay separately, WHB and SHB) as well as the number of “ice-free” days based on those dates. “Ice-free” in the following figures refers to 30% sea ice concentration (other thresholds are 20%, 30%, 40%, 50%). The data is from NASA satellites and available from 1979 (Source: https://nsidc.org/data/g02202/versions/4). The solid straight lines shows the long-term linear trends. The maps on the right show the sea ice concentration map at the last freeze-up and break-up dates (or current sea ice conditions).
Take away message: the length of the ice-free season varies considerably from year to year, but the long-term trend is consistently towards a longer ice-free season. The ice-free season has lengthened by about one month since 1979. A longer ice-free season means a longer period without access to food (seals) for polar bears.
Hudson Bay July average sea ice concentration
The month of July is typically when the sea ice breaks up and polar bears start to come on shore for the summer. A late ice break-up date can provide prolonged hunting opportunities, benefiting the well-being of polar bears, while an early break-up means an early start to the ice-free fasting season.
Pattern during sea ice break-up and freeze-up in Western Hudson Bay (WHB)
The way in which sea ice melts and breaks apart is a little different each year. Below is the sea ice pattern at the time of break-up (sea ice in WHB < 30%) each year. Typically, some ice lingers in the center and southern shore of Hudson Bay, but some unusual years, like 2024, have the last ice hang on in WHB near Churchill.
Break-up dates Western Hudson Bay:
Freeze-up dates Western Hudson Bay:
Difference in length of ice-free season between Western (WHB) and Southern Hudson Bay (SHB)
Sea ice tends to break up a few days later in the Southern Hudson Bay (SHB) than in the Western Hudson Bay (WHB) and this difference might prompt polar bears in a given year to migrate with the sea ice to stay with favorable hunting grounds as long as possible during the melt season, though this has been difficult to show conclusively in tracking data.
Below figure shows that there has been a tendency through 2015 for sea ice to break up later in SHB than WHB, though that trend was not significant and can mostly be explained by year-to-year variations in wind: stronger westerly winds in a given year will transport more sea ice from WHB to SHB, where it piles up and becomes thick, thus taking longer to break up during the melting season. See this study for more details.
SHB freezes up about 13 days after WHB and there is currently no trend in that number over time. Below figure is for 30% sea ice threshold, other thresholds can be found here: 20%, 30%, 40%, 50%.
Recent temperatures (and their departure from normal) at Churchill airport
Toy model of polar bear movement during a winter season