Penguins and climate change
Penguins are flightless birds primarily found in the Southern Hemisphere, known for their aquatic lifestyle and unique adaptations to cold environments. While many people associate penguins with Antarctica, they inhabit a range of southern regions, including the Galapagos Islands. These birds rely on sea ice for critical aspects of their life cycle, such as breeding and feeding. Climate change poses significant threats to penguin populations, particularly cold-adapted species that depend on stable ice conditions. Warming temperatures lead to thinning ice, which can disrupt breeding cycles and reduce available habitat. For instance, melting ice not only limits breeding grounds but also diminishes the food supply by affecting the algae that sustain krill populations. Some penguin species are experiencing dramatic population declines, such as the emperor penguin, which has become threatened due to these environmental changes. However, not all populations are equally affected; some are thriving due to changes in food availability. The complex interplay between climate change, food sources, and penguin breeding illustrates the broader impact of environmental shifts on wildlife.
Penguins and climate change
Definition
Penguins are aquatic, flightless birds that exclusively inhabit the Southern Hemisphere. Though popularly associated with Antarctica, penguins inhabit all southern continents, extending as far north as the Galapagos Islands off the coast of Ecuador. In fact, only a few penguin species live in the southernmost regions, and at least ten species live in the temperate zone. Most penguins spend half of their lives on land and half in the oceans. They feed on small marine creatures such as krill, fish, and squid while swimming underwater.
Significance for Climate Change
Cold-species penguins are dependent on Antarctic ice, but temperature increases thin ice shelves, which can adversely affect penguin populations. Antarctic warming led to the collapse of portions of the Antarctic Larsen ice shelf in 2002, reducing important penguin breeding and feeding areas and drowning thousands of emperor penguin chicks, who were forced to take to the water before they learned to swim. Some scientists believe cold-species penguins are indicators of the health of Antarctic ecosystems and the consequences of Antarctic climate change. Collapsing sea ice significantly affected emperor penguins again in 2023, according to the British Antarctic Survey. Under normal conditions, chicks hatch between late July and mid-August. They are reared on the sea ice until December, when they develop waterproof feathers. However, if the ice melts too early, they are at risk of freezing or drowning. In 2023, fourteen of sixty-six colonies had high chick mortality rates because of melting sea ice.
Global climate changes can perturb the distribution of penguin food sources and harm the health of cold-species penguin populations. During the winter, marine algae freeze into the ice pack. Ice melts during the spring, which releases algae to be eaten by krill. This increased food source expands the krill population in time for the penguin’s spring breeding time. Warming decreases winter ice, which decreases the release of algae and, consequently, the surge in krill population. Less food available for breeding penguins reduces penguin fertility.
Not all penguin populations are equally affected by global climate change. In 2022, some populations were estimated to be only 10 percent of their original size, and emperor penguins were added to the threatened species list. Adélie penguins—the most southerly distributed penguin species, which inhabits the area from South Africa’s Prince Edward Islands to the Antarctic Peninsula—are declining. Penguin populations in the Indian Ocean and more southerly regions of Antarctica are thriving. In some cases, penguin populations thrive because they have access to their primary food source earlier in the breeding season. In other cases, shifts in the location of the primary food source forces penguins to forage farther to feed, reducing their fertility.
These changes in food availability are due to the Antarctic Circumpolar Current (ACC), which mixes 140 million cubic meters of water from the Indian, Pacific, and Atlantic Oceans and flows from west to east around Antarctica. The ACC is filled with krill and other penguin food sources. Climate change can alter wind patterns and drive the ACC away from or closer to penguin nesting sites, affecting their populations directly (by increasing or decreasing food supply) and indirectly (because food supply affects fertility).
Bibliography
Cimino, Megan A., et al. "Projected Asymmetric Response of Adélie Penguins to Antarctic Climate Change." Scientific Reports, vol. 6, 29 June 2016, doi:10.1038/srep28785. Accessed 11 Dec. 2024.
Dzombak, Rebecca. “Penguins Are Slow to Evolve, Making Them Vulnerable to Climate Change.” National Geographic, 26 July 2022, www.nationalgeographic.com/animals/article/penguins-are-slow-to-evolve-and-vulnerable-to-climate-change. Accessed 11 Dec. 2024.
"Emperor Penguin Colonies in Antarctica Suffer as Sea-Ice Diminishes." British Antarctic Survey, Natural Environment Research Council, 15 Apr. 2024, www.bas.ac.uk/media-post/emperor-penguin-colonies-in-antarctica-suffer-as-sea-ice-diminishes/. Accessed 12 Dec. 2024.
"Melting Sea Ice Threatens Emperor Penguins, Study Finds." Woods Hole Oceanographic Institution, 20 June 2012, www.whoi.edu/news-release/melting-sea-ice-threatens-emperor-penguins--study-finds. Accessed 11 Dec. 2024.
Sidder, Aaron. "Antarctica Could Lose Most of Its Penguins to Climate Change." National Geographic, 29 June 2016, news.nationalgeographic.com/2016/06/adelie-penguins-antarctica-climate-change-population-decline-refugia/. Accessed 11 Dec. 2024.