Temperature is a limiting factor for polar bears primarily because they are highly adapted to cold Arctic environments and rely on sea ice for hunting and survival. Their thick fur, two layers of dense fur, and a substantial fat layer (up to about 11.4 cm thick) insulate them against extreme cold, allowing them to thrive in temperatures as low as -40° to -50°C (-40° to -58°F)

. However, rising temperatures due to climate change cause sea ice to melt earlier in the year and freeze later, drastically reducing the time polar bears have to hunt seals, their main prey, on the ice

. This loss of sea ice habitat limits their ability to find food, leading to malnutrition, starvation, and decreased reproductive success. Additionally, warmer temperatures can cause polar bears to overheat because their insulation is optimized for cold, not heat. In summer, especially in southern parts of their range where temperatures can reach up to 30°C (86°F), polar bears must rest more and seek cooler areas to avoid overheating

. The longer, warmer summers also force polar bears to spend more time on land, where food is scarce and exposure to new diseases and human activities increases, further threatening their survival

. In summary, temperature limits polar bears by:

• Restricting sea ice availability, which reduces hunting opportunities and access to food.
• Increasing the risk of overheating due to their cold-adapted physiology.
• Extending ice-free periods, causing longer fasting and increased energy stress.
• Exposing them to new environmental threats as they spend more time on land.

These factors collectively threaten polar bear populations by impairing their ability to maintain energy balance and reproduce successfully in a warming Arctic