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 -Migrations 6. Conclusionary Thoughts

The Hockey Stick Graph!

National Snow and Ice Data Center

noaa.gov

Modeled Sea Ice

March Sea Ice March Sea Ice Canadian Center for Climate Modeling and Analysis (CCCma) Coupled Global Climate Model

Polar Bear Range Polar Bear Range

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)

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 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.

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.

Summary of Affects 1) Longer Journey to Den Sites 3) Shorter Feeding Seasons 2) More Energetic Migrations

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

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.

References