The Antarctic Peninsula, where about three million pairs of penguins breed, is one of the most quickly warming areas on the planet; its average temperature has increased by five degrees Fahrenheit over the past 75 years. Many scientists believe that this warming will endanger some penguin colonies in two ways: dwindling food and loss of nesting habitats. On the rocky shores of Deception Island, where the penguins breed, they need cold, dry land for their eggs to survive, but rising temperatures have introduced rain and pools of water to nesting sites. And because of the rapid loss of sea ice, krill — the tiny crustaceans that serve as penguins’ main source of food — can’t sustain the large colonies they need to thrive. The penguin population of Baily Head, in the northern part of Antarctica, seems to have dropped from 85,000 breeding pairs in 2003 to 52,000 seven years later, a decline of almost 40 percent. Scientists fear that as warm water shifts farther south along other coastal regions, larger populations of penguins could face a similar decline. Image by George Steinmetz. Antarctica, 2017.