Antarctica Is Warming Quickly, And That’s Bad News For Penguin Colonies

by Alejandro Davila Fragoso

Jun 29, 2016 

 

CREDIT: Flickr/Marie and Alistair Knock

An Adelie penguin surveys the landscape from a rock slope on Petermann Island, Antarctica

About a third of Adelie penguin colonies in Antarctica could disappear in the next four decades due to human-caused global warming, a figure that could balloon to more than half by the end of the century, a new study published Wednesday found.

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.

The poles are warming faster than most of the planet. For Antarctica, that means rapid ice melt at increased rates. The Antarctic Peninsula north of the continent has warmed some 2.5 degrees Celsius — 4.5 degrees Fahrenheit — since 1950, according to the National Science and Ice Data Center (NSIDC). Meanwhile, the West Antarctic Ice Sheet is losing mass, likely due to warmer water deep in the ocean near the coast. The NSIDC reports that some stations in East Antarctica show some cooling, but that in general Antarctica is warming up. According to a 2015 study, ice shelves in West Antarctica have lost some 18 percent of their volume over the last two decades.

West Antarctica is seeing dramatic ice loss particularly the Antarctic Peninsula and Pine Island regions. Ice loss culprits include the loss off buttressing ice shelves, wind, and a sub-shelf channel that allows warm water to intrude below the ice.

CREDIT: NASA/NSIDC

Funded through the 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.

According to the study, late 20th-century climate warming along the West Antarctic Peninsula coincides with Adelie population declines, while stable or cooling conditions in the rest of the continent generally cause stable or increasing populations. Indeed, population improvement has been ongoing in East Antarctica, where Adelie penguins almost doubled over the past 30 years, according to a 2015 Australian Antarctic Division study.

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.

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