CREDIT: Flickr/Marie and Alistair Knock
Published in Scientific Reports, the study projects dramatic colony losses by 2060 as global warming affects nesting and potentially the penguins’ food supply of krill and fish. “With these numbers it’s important to note that we are talking about 30 percent of the current Adelie colonies … not the population. For example, there are about 200 Adelie colonies, but within those colonies, there [are] millions of penguins,” Megan Cimino, lead author and postdoctoral scholar at Scripps Institute of Oceanography, told ThinkProgress.
Characterized by a white halo around the eyes, Adelie penguins are fast-swimming predators that breed on the coasts of the southernmost continent of the planet. As of 2014 there were some 3.79 million breeding pairs of Adelie penguin, according to Audubon.
Like other penguin species, Adelie penguins have historically benefited from some warming, which allows better access to rock breeding grounds and the ocean for foraging. However, Cimino and colleagues at the University of Delaware report that warming benefits may have a tipping point. “It is only in recent decades that we know Adelie penguins’ population declines are associated with warming, which suggests that many regions of Antarctica have warmed too much and that further warming is no longer positive for the species,” she said.
NASA Biological Biodiversity research program, the University of Delaware study is based on 30 years of satellite observations of Adelie penguin colonies. Researchers examined the number of years from 1981 through 2010 that endured unusual climate during the chick-rearing period. They then used these observations and combined them with climate models to project habitat suitability from 2011 through 2099. Cimino said scientists know sea surface temperature and sea ice concentration affect Adelie survival, but the exact dynamic of how that happens is unclear. So far it's known that climate change can affect penguins’ nesting sites and food. For example, precipitation and snowmelt can cause flooding that drowns eggs and small chicks.
So there is a glimmer of hope for the Adelie penguin. Since the effects of global warming will likely be site-specific, some parts of Antarctica will remain suitable for penguins, Cimino said. This means Adelie penguins might in the coming years march to these buffers zones for survival. The Capa Adare region in East Antarctica, home to the earliest known penguin colony, is one of these areas.
"Though the climate there is expected to warm a bit, it looks like it could be a [refuge] in the future, and if you look back over geologic time, it was likely a refuge in the past," she said.