"Yan Ropert-Coudert, senior penguin scientist at Dumont D'Urville research station, adjacent to the colony, said the region was impacted by environmental changes linked to the breakup of the Mertz glacier."
Hmm, now why would a glacier breakup?
Reading is fun.......
because it cracked due to the cold. you should read.
"But they have been declining in the Antarctic region more generally where climate change has taken its toll, with shifting ice reducing habitat
while warming seas affect their prey.
Four years ago, the same colony, which numbered 20,196 pairs at the time, failed to produce a single chick.
Heavy sea ice, combined with unusually warm weather and rain followed by a rapid drop in temperature, resulted in them becoming saturated and freezing to death."
Calving of ice sheets extending out over the ocean is a natural occurrence.