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Polar Bears and Sea Ice: Implications of Global Warming. 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
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Polar Bears and Sea Ice: Implications of Global Warming
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 6. Conclusionary Thoughts
1971-1990 March Sea Ice 2081-2100 March Sea Ice Canadian Center for Climate Modeling and Analysis (CCCma) Coupled Global Climate Model
Feeding ~Polar Bears feast on Ringed and Bearded seals for 7-8 months of the year. Ringed Seal (CUTE) ~ During feeding time, polar bears have to triple their body weight in fat. Bearded Seal (TASTY) ~ The seals migrate at the end of summer, and polar bears have to go 3-4 months without food.
Denning ~ To conserve their stores of fat, polar bears den for the months they don’t have access to seals. ~ 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 travel to terrestrial sites to den, migrations to and from den sites taking as much as three weeks ~ They return to the sea ice when it has extended and seals have migrated back to raise their own young.
Migrations ~ Almost half of cubs lose their lives in their initial migration to sea ice from their maternal den site. ~ 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.
Summary of Affects 1) Longer Journey to Den Sites 2) More Energetic Migrations 3) Shorter Feeding Seasons
BODY MASS Why it is so important to have fat ~ Smaller cubs have a lower survival rate ~ Adult Polar Bears have been shown to lose up to .9 kg of body mass per day in summer. ~ A lengthening of time between successful weaning of offspring ~ 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
PROOF ~ 10% Drop in Adult Body Mass over the past 20 years ~ 10% Drop in number of cubs born over the past 20 years.
It has been predicted that within 100 years, polar bear body mass will be below the level capable of reproducing.