evidence: The impact of climate change on a particular species can ripple through a food web and affect a wide range of other organisms. For example, the figure below shows the complex nature of the food web for polar bears. Not only is the decline of sea ice impairing polar bear populations by reducing the extent of their primary habitat, it is also negatively impacting them via food web effects. Declines in the duration and extent of sea ice in the Arctic leads to declines in the abundance of ice algae, which thrive in nutrient-rich pockets in the ice. These algae are eaten by zooplankton, which are in turn eaten by Arctic cod, an important food source for many marine mammals, including seals. Seals are eaten by polar bears. Hence, declines in ice algae can contribute to declines in polar bear populations.[2][6][7] [...] Even within a single ecosystem, there can be winners and losers from climate change. The Adélie and Chinstrap penguins in Antarctica provide a good example. The two species depend on different habitats for survival: Adélies inhabit the winter ice pack, whereas Chinstraps remain close to open water. During the past 50 years, a 7–9°F increase in midwinter temperatures on the western Antarctic Peninsula has led to a loss of sea ice. Over the past 25 years, the population of Adélie penguins decreased by 22%, while the population of Chinstrap penguin increased by an estimated 400%.[13]