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Polar Bears and Sea Ice: Implications of Global Warming
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OUTLINE 1. Global Warming A) Arctic Warming 2. Polar Bear Range A) Annual/Perennial Ice B) Denning C) Seals 3. Sea Ice today 4. Sea Ice predictions 5. What it means to Polar Bears -Reproduction/Body Mass -Migrations -Migrations 6. Conclusionary Thoughts
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The Hockey Stick Graph!
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National Snow and Ice Data Center
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noaa.gov
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Modeled Sea Ice
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1971-1990 March Sea Ice2081-2100 March Sea Ice Canadian Center for Climate Modeling and Analysis (CCCma) Coupled Global Climate Model
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Polar Bear Range Polar Bear Range
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Ringed Seal (CUTE) ~ During feeding time, polar bears have to triple their body weight in fat. ~Polar Bears feast on Ringed and Bearded seals for 7-8 months of the year. ~ The seals migrate at the end of summer, and polar bears have to go 3-4 months without food. Feeding Bearded Seal (TASTY)
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Denning ~ To conserve their stores of fat, polar bears den for the months they don’t have access to seals. ~ They travel to terrestrial sites to den, migrations to and from den sites taking as much as three weeks ~ Polar Bears are the opposite of all other bears in that they are able to hibernate at any time of year within 7- 10 days after the removal of resources. ~ They return to the sea ice when it has extended and seals have migrated back to raise their own young.
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Migrations ~ Each year in late fall, mothers with their new cubs make the journey back to sea ice ~ With Increasing distance to migrate and therefore energy used, Polar Bears will have an increasingly hard time making the migration back to feed. ~ Almost half of cubs lose their lives in their initial migration to sea ice from their maternal den site.
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Summary of Affects 1) Longer Journey to Den Sites 3) Shorter Feeding Seasons 2) More Energetic Migrations
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BODY MASS Why it is so important to have fat ~ Adult Polar Bears have been shown to lose up to.9 kg of body mass per day in summer. ~ Female bears below 189 kg are unable to successfully reproduce ~ Reduced percentage of females able to make the return journey to dens and then to sea ice in winter ~ Females with lower fat stores produce smaller cubs ~ Smaller cubs have a lower survival rate ~ A lengthening of time between successful weaning of offspring
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PROOF ~ 10% Drop in Adult Body Mass over the past 20 years ~ 10% Drop in number of cubs born over the past 20 years.
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It has been predicted that within 100 years, polar bear body mass will be below the level capable of reproducing.
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References
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