A changing climate has strong implications for biodiversity. Studies of fossil and pollen distribution show that species are very sensitive to climate changes. When the climate changes, species often die out in their present areas and colonize new areas. Therefore, as the climate changes in the future, there will be disruption of natural communities and extinction of populations and species.

Which of these environmental changes would most affect the arctic polar bears survival?

A)
drought

B)
an ice age

C)
deforestation

D)
global warming