Since 1974, Bill Fraser, a researcher with the Palmer Long-Term Ecological Research LTER and president of Polar Oceans Research Group, has been studying the ecosystem of the northwestern Antarctic Peninsula, where the midwinter temperature has risen 11°F in just 60 years, making it one of the three most rapidly warming regions on the planet. So, it’s not a coincidence that since the mid 1970s, the penguin population in this zone has dropped some 85 percent to about 5,000, a depletion rate mirrored in other colonies on the northwestern Antarctic Peninsula. There are some 2.5 million Adélie penguins in all of Antarctica.
As explained to the Penguin Post, the main cause is melting sea ice in the Southern Ocean surrounding the Antarctic Peninsula where glaciers have retreated nearly 90 percent in the last three decades. There are now three fewer months of sea ice every year than there were in 1979, which means fewer krill larvae at the sea-ice edge and fewer silverfish eggs able to take refuge and mature beneath it. Penguins use the sea ice as a feeding platform to feed on both, which means that the lack of sea ice is a triple whammy. It lowers the penguins’ two main food sources at the same time that it limits their access to an increasingly slim supply. Higher sea and air temperatures have also led to both more snow and more snow melt, both of which are problematic for the penguins. Deeper snowfall makes it harder to build nests. And once the snow melts, penguins find their eggs swimming in pools of icy water.
Meanwhile, Gentoo penguins are moving south to Antarctica, replacing the Adélies. Where there were once few fur seals there are now thousands. “Ice-loving, ice-dependent species are fairing poorly, and ice-avoiding species are moving in. It’s kind of a natural process,” Montaigne said, hastening to add, “I’m not saying it’s a good process.”