Climate Change on the Antarctic Peninsula
Written by Scott Doney, Joe D. and Helen J. Kington Professor in Environmental Change, Dept. of Environmental Sciences, College and Graduate School of Arts & Sciences
When I tell people that I study the Antarctic Ocean, they likely envision intrepid scientists trekking off to explore towering glaciers, vistas covered with sea-ice and icebergs, vast penguin colonies, and pods of feeding humpback whales. All of which is true for the science team of the Palmer Long Term Ecological Research (LTER) program, which I was fortunate to join about a decade ago. What people probably do not think about is that the rapidly warming Antarctic Peninsula is also an excellent natural laboratory for studying climate change and its impact on marine life.
The Antarctic Peninsula juts out from the main continent towards South America, much like a thumb from a closed fist. The climate on the peninsula is milder and warmer than the main continent, and open water is found in coastal regions during late spring and summer on the western side of the Peninsula as the seasonal sea-ice cover melts or is blown out to sea. The combination of long summer days, shallow ocean, mixed layers from the freshwater added from sea-ice and glacial melt, and nutrient-rich waters leads to intense summer phytoplankton blooms. These blooms, in turn, support large populations of krill, small crustaceans related to shrimp that thrive along the ice edge. Krill are a favorite abundant and reliable food supply for Adélie penguins that establish summer breeding colonies each year on coastal islands and humpback and other baleen whales that migrate to the Antarctic Peninsula to feed during the summer.
Climate conditions on the northern part of the Peninsula are changing rapidly: both the ocean and atmosphere are warming at rates as fast as anywhere on the planet; the amount of time each year with sea-ice cover is declining; and about 90% of the continental glaciers are retreating. These physical changes echo throughout the marine food-web. The most intense phytoplankton blooms are occurring further south along the peninsula, and krill populations appear to be dropping near the northern tip of the peninsula. Adélie penguins are adapted to a life in polar conditions with abundant sea-ice, and in some locations along the peninsula Adélies are disappearing, being replaced by other penguin species like Gentoo and Chinstraps that like warmer and more ice-free conditions.
The Palmer LTER team has been monitoring these changes along Antarctic Peninsula routinely since the early 1990s, with some historical data extending back even earlier. Every austral spring, students, technicians, and scientists from the team head to the southern tip of Chile for the four-day trip to Antarctica Peninsula on a small research vessel across the notoriously stormy Drake Passage. Based out of the U.S. Palmer Station on the western side of the Antarctic Peninsula, team members use small Zodiac inflatable boats to sample nearby waters for changing seawater chemistry, plankton and krill, and survey local penguin breeding colonies. Over the past several years, high-tech robotic ocean gliders and airborne drones have been added to expand our geographic coverage. During the height of the summer, the team also conducts a month-long ocean research expedition on the same ship used to transit from Chile. Traveling south from Palmer Station towards the pole, the research ship surveys other penguin colonies and ocean conditions from near the shore out to deep-water over a several hundred kilometer stretch of the peninsula.
My role on the Palmer team is to bring some sense to this wealth of ocean physical, chemical and biological field data using numerical models, satellite remote sensing, and (big) data science. Although much of my time is spent sitting in front of a computer screen, I travel down to Antarctic every few years, and the chance to visit the Antarctic and view penguins and whales in a spectacular polar environment is a big draw for many students in my group. So too, of course, is the challenge of understanding the impact of climate change on the invaluable Antarctic Ocean ecosystem and to learn lessons that may be applicable to other ocean regions closer to home.
For more information on Antarctic Ocean research see the Palmer LTER website: http://pal.lternet.edu/
To get a glimpse of what life is like on a Palmer LTER research expedition see the feature-length film produced by Rutgers University students, Antarctic Edge: 70 degrees South: https://beyondtheice.rutgers.edu/
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