Scripps Scientists Explore Antarctica: Glaciers, Microbes & More

Article Content Seals resting on sea ice floes in the west side of the Antarctic Peninsula near Marguerite Bay, 68°S, in 2023. Credit: Allison Cusick Scientists from UC San Diego’s Scripps Institution of Oceanography and the Scripps Polar Center are at the bottom of the world conducting field research in Antarctica this season. The traditional scientific field season lasts from December through February during the Antarctic summer, which features slightly warmer temperatures and longer days. During the 2025-2026 Antarctic field season, Scripps scientists are conducting research projects including an investigation into the mechanisms driving ice loss at Thwaites Glacier, an exploration of cancer-fighting compounds produced by microbes living inside Antarctic sea squirts and research on how penguin guano shapes phytoplankton communities. This season has been marked by reduced support for Antarctic research by the National Science Foundation (NSF), including the cessation of operations of research vessel Nathaniel B. Palmer, the only U.S. research icebreaker dedicated to Antarctic research. This is the first time in nearly six decades that the U.S. Antarctic Program has been without at least one dedicated research vessel for forays into the Southern Ocean, despite the Trump Administration’s call to strengthen Antarctic research infrastructure. Bruce Appelgate, Scripps’ associate director and head of ship operations, called the loss of R/V Palmer a “gut punch” for the scientists who rely on ships to conduct their research in the Southern Ocean. For this field season, NSF is using two substitute ships from the U.S. Academic Research Fleet, research vessels Sikuliaq and Scripps-operated Roger Revelle, but neither ship was designed for heavy use in Antarctica. The ships’ limitations in thick sea ice mean they can only work in relatively ice free areas such as the western Antarctic Peninsula, and that scientists studying the icier reaches of East and West Antarctica will need to find new vessels. Despite the obstacles, Scripps Polar Center researchers are in Antarctica this field season. Exploring Retreating Ice Shelves Scripps researcher Jamin Greenbaum’s fieldwork takes place at Thwaites Glacier, which satellite monitoring has identified as the largest of the fastest retreating glaciers that drain the West Antarctic Ice Sheet. Thwaites holds enough ice to raise global sea level by roughly two feet if it were to collapse entirely, and its retreat could destabilize neighboring glaciers containing even more ice. Prior expeditions discovered warm (for the Antarctic) water just beneath the glacier’s ice shelf that is contributing to its melting from below. This year, Greenbaum’s goal is to collect water samples and other measurements from beneath Thwaites’ thick floating ice to disentangle the drivers of its rapid melting. Greenbaum was nearly unable to return to Antarctica to collect this data. His federal proposals received high scores but none related to the Thwaites work were funded, leaving Greenbaum to consider the possibility that he might not be able to mount an expedition or to do so alone or with one other person on a shoestring budget. However, in November 2025, just before the start of the Antarctic field season, Greenbaum heard from the Fund for Science and Technology that the foundation would support his research and enable a return to Antarctica to continue the work with a four-person team. He also received support from the Explorer’s Club Impact Grant Program and Scripps Seed Grant Program which were instrumental for equipment procurement and logistics. Greenbaum and his colleagues are travelling south aboard the Korea Polar Research Institute’s research icebreaker Araon from late December through the middle of February. To collect water from beneath Thwaites, Greenbaum’s team will use a special floating platform that will be carried out to rifts in the ice shelf by helicopter where it will then lower and retrieve sampling equipment with a winch. These rifts are fractures in the ice shelf that cut through its entire thickness, representing the first stage of the process by which chunks of the shelf break off and become icebergs. One hypothesis the team is hoping to test directly is whether meltwater flowing out to sea from beneath the glaciers’ ice shelves might be contributing to the localized warming and accelerating ice loss. Greenbaum said that understanding the processes driving the rapid melting occurring beneath Thwaites could improve scientists’ ability to forecast sea-level rise because the same processes are likely occurring beneath other melting glaciers. Additionally, Greenbaum and his collaborators will be testing an underwater acoustic system of beacons and receivers that could one day serve as the basis for a kind of underwater GPS that would allow autonomous robots to triangulate their position and navigate the treacherous undersea environment of the Antarctic. If the tests are successful, future undersea robots could collect data from previously inaccessible parts of the Southern Ocean. During the voyage south, Greenbaum also facilitated an Active Bystander Intervention workshop attended by 26 expeditioners from Australia, Canada, Taiwan, the U.S. and the U.K. Part of a new initiative at Scripps called PEERS started by Greenbaum in 2022, the workshop aims to provide practical tools for handling difficult interpersonal situations that can arise in the field. Several journalists are currently aboard the Araon reporting on the expedition. Their coverage is being shared on the PBS website and in The New York Times. Decoding Cancer-Fighting Compounds in Antarctic Sea Squirts One of the expeditions affected by the sudden loss of R/V Palmer was that of Scripps cell biologist Martín Tresguerres, who leads the Allen Discovery Center for Neurobiology in Changing Environments. He and his collaborators were scheduled to head to Antarctica aboard the Palmer in October to study a microbe that produces a cancer-fighting molecule, but were forced to upend their plans and reschedule for February aboard the University of Alaska Fairbanks-operated research vessel Sikuliaq. The delay caused major disruptions for researchers like Tresguerres who had to renegotiate teaching and service schedules, research commitments, childcare and their spouses' work schedules in addition to shortening the expedition by a week. Still, Tresguerres counts himself lucky to still be heading south to complete his field research this season when others will be unable to. The microbe that Tresguerres and his colleagues hope to study lives inside an ascidian, or sea squirt, on the Antarctic sea floor. The compound the microbe produces, called “palmerolide A,” has shown potential as a treatment for melanoma, a dangerous form of skin cancer. With Alison Murray of the Desert Research Institute in Nevada and Bill Baker of the University of Southern Florida who helped discover the microbe, Tresguerres hopes to study the relationship between the palmerolide A-producing bacterium and its sea squirt host. Scripps students Maitri Paul and Ria Bhabu and Phil Zerofski, Scripps’ Experimental Aquarium manager and curator, will also take part in the expedition. The team’s fieldwork, funded by NSF, will take place along the Antarctic Peninsula. With the help of Tresguerres, the team seeks to decode how the bacterium makes palmerolide A, which has proved challenging to recreate in the lab, as well as the compound’s biological function. One of the ways the researchers will explore the compound’s function in nature is by looking for where the microbes are present in the sea squirt. If, for example, the microbes are only present in the sea squirt’s gut then maybe the function is related to digestion, said Tresguerres. Or, the compound may somehow help the microbes live inside the sea squirt, which could give scientists clues about how microbes and animals have evolved to coexist at the molecular level. Once revealed, the biological function of the compound could help scientists better predict how these creatures might respond to environmental changes such as warming and ice melting. Another important piece of the team’s work this field season will be surveying where this sea squirt is found in the Antarctic environment, using a remotely-operated vehicle (ROV). Specimens can be collected by the ROV, and also via scientific divers with expertise diving in Antarctic conditions. The surveys will establish a baseline for the organism’s distribution and provide a basis for comparison as Antarctica continues to change. Investigating Penguin Nutrients and Phytoplankton Using Viking Expeditions ships as a base of operations, Johnson and his colleagues are examining how nutrients from penguin guano, currents and other sources promote phytoplankton growth — specifically whether particular nutrient sources favor larger, more nutritious phytoplankton called diatoms. The answer to this question matters for climate projections because the Southern Ocean is responsible for roughly 20-40% of global CO2 removal, and larger phytoplankton species are more effective at sequestering carbon. These diatoms are also a vital food source for Antarctic Krill — the keystone species in the Southern Ocean. After collecting water samples in the field, the researchers perform DNA sequencing aboard the ship using technology from Oxford Nanopore, which will then be validated using traditional Illumina sequencing back in San Diego. This method produces results within about 48 hours instead of months to years, allowing researchers to observe trends and adjust sampling in near real-time as the ship revisits sites every 11-14 days. Sightseeing and Science The GASP program grew out of an earlier collaboration between Scripps, Argentina's Universidad Nacional de la Plata, and Antarctic tour operators called FjordPhyto, a citizen science program, in which tour guests assist trained expedition staff in collecting samples of Antarctic phytoplankton as well as ocean data. The tour guests also have the opportunity to attend lectures from Scripps researchers such as postdoctoral researcher Allison Cusick, who will be in Antarctica this season in February. The program leverages the fleet of the International Association of Antarctica Tour Operators (IAATO) expedition vessels that bring their guests to experience the Antarctic Peninsula from November through March each year. Prior to each austral summer, the FjordPhyto team trains staff on the ships to guide travelers in collecting phytoplankton samples as well as temperature and salinity data at popular landing sites near glaciers. The samples are then analyzed for phytoplankton species diversity, abundance and carbon biomass by colleagues at Argentina’s Universidad Nacional de La Plata and back at Scripps in the lab of Andrew Allen, which is a joint venture with the J. Craig Venter Institute. The many citizen scientists visiting Antarctica collect a volume of data over the whole field season that would be impossible for scientists to gather alone given the vastness of Antarctic coastal waters. With the help of more than 10,000 travelers since the program launched, FjordPhyto has created a multi-year record of how phytoplankton communities are changing in response to glacial meltwater. Changes in phytoplankton composition can ripple up through krill populations to affect penguins, seals and whales. Researchers have documented previously unknown species of phytoplankton and revealed patterns in phytoplankton community dynamics over the season. Pressing Forward Despite the challenges facing U.S. Antarctic research this season, Scripps scientists are continuing with critical interdisciplinary studies that address questions with global implications. The loss of the Palmer research icebreaker and cuts to federal funding have forced researchers to find creative solutions and new partnerships. “We will get the science done and support it, but this is not a sustainable path for American science,” said Appelgate, who is also the chair of the University-National Oceanographic Laboratory System, which manages the U.S. fleet. “These replacement ships aren’t the right tools for the job. You can mow the lawn with a weed whacker, but it’s not the right tool.” Follow Scripps Oceanography on Instagram, Bluesky and other social media channels for the latest expedition updates.