Scott Braddock was awarded the AAC’s Research Grant in 2019 to study glacial recession in Patagonia. Specifically, Scott and his team were studying the Southern Patagonian Icefield. With the Southern Patagonian Icefield contributing a disproportionate amount of ice loss relative to the size of the icefield when compared with other mountain glaciers around the world, better understanding the mechanisms for tidewater glacier retreat in this region are critical for projections of future ice loss. Below is a quick summary of his project, and a report on the initial findings. 

Why This Research? Why now?

Like most glaciers around the world, the Southern Patagonian Icefield (SPI) is retreating in the face of rising atmospheric and ocean temperatures. The SPI is particularly susceptible to a changing climate because of its relative proximity to the equator and the fact that it is made up of low-elevation alpine and tidewater glaciers that are highly sensitive to changes in temperature and precipitation. Past studies have shown that ice mass loss from the Southern Patagonian Icefield contributes a large amount of water to global sea level rise, especially relative to the size of the icefield, with rates increasing in recent decades. However, how quickly the SPI is continuing to respond to warmer conditions and the primary mechanisms behind ice mass loss remain important questions to be answered. Scott’s team is attempting to investigate these very questions.

The glaciers of the SPI are located in Chile’s largest protected area, Bernard O’Higgins National Park (BONP), which hosts the largest known population of the endangered huemul deer–a species whose health is connected with recently-deglaciated habitat. Under the supervision of Coporacion Nacional Forestral (CONAF), limited in situ research exists in the BONP due to the frequent inclement weather, poor access, and only a handful of CONAF park guards and scientists to protect and manage a large area. Given the results of studies highlighting the accelerated retreat of the SPI in the past several decades, further work is necessary to better constrain estimates of ice loss and glacier stability as well as impacts on biodiversity in BONP.

The Grant Funded Trip & Moving Beyond Covid

In October 2019, supported by research grants from the American Alpine Club, Churchill Foundation, and the Geological Society of America, Scott’s team traveled to Chilean Patagonia to sample ocean water in contact with several glaciers to understand how this interaction may influence rapid retreat of ice in the region. The team sampled water temperature and salinity at the surface and to depths up to 10 m and collected data on surface reflectance, suspended sediment and plankton in front of two tidewater glaciers, Bernardo and Témpano, in Bernard O’Higgins National Park, Chile. Results show a clear boundary between fresh glacial runoff and warm ocean water around 6 m depth close to the terminus of Témpano Glacier. 

In coordination with sampling efforts, Scott’s team set up time-lapse cameras overlooking both glaciers to track iceberg movement and try to observe sediment plumes and surface currents. Additionally, they witnessed one of the earliest-known glacial lake outburst floods (GLOF) in a summer season at Bernardo Glacier. 

In witnessing this event, it is clear that to fully understand this dynamic ice-ocean system, we need longer duration measurements to capture both episodic events (GLOFs) and persistent forcing (ocean warming). To aid in long-term monitoring of ice/ocean interactions and GLOF events in this region, Scott’s team facilitated an agreement between three organizations participating in this project—Coporacion Nacional Forestral (CONAF), Round River Conservation Studies (RRCS), and UMaine Ice/Ocean group to continue this research in the coming years by sharing logistical support, scientific equipment, and data. 

In the context of Covid, the collaborative nature of this project has been crucial to its continuity. The project included team members from three organizations and many backgrounds coming together to work in such a remote, challenging environment. The glaciology portion of this research project was designed and led by Dr. Kristin Schild, University of Maine School of Earth and Climate Sciences. The marine biology part of the project was designed and led by Raúl Pereda, a Marine Biologist with CONAF. Logistics, help with the science, and local knowledge and expertise were provided by Felidor Paredes, CONAF Park Guard and Fernando Iglesias Letelier, Chilean Program Director for RRCS.

Like most international research, COVID has disrupted the US team’s return to Patagonia for the last two years. However, to keep the project moving forward, Scott’s team will ship equipment to Chile so that team members from CONAF can continue taking measurements of ocean water in front of these tide water glaciers to monitor how ocean properties are influencing glacial retreat of the Southern Patagonian Icefield as well as impacts retreating glaciers might have on the marine biology. 

A Snapshot of the Science Behind Glacial Recession:

The speed at which glaciers of the Southern Patagonian Icefield (SPI) flow could be driven in two distinct ways: from the top-down, or the bottom-up (Figure 2a-e). How fast the glacier moves or flows influences how quickly it retreats and thins over longer time scales.

In the top-down scenario, warm air temperatures melt the glacier ice and, when combined with precipitation, the glaciers are inundated with liquid water (Figure 2a). This water flows under the glacier, lubricating the interface between the glacier and the bedrock, and accelerates the speed at which the glacier moves due to a decrease in friction (Figure 2b).

In the bottom-up scenario, the warm ocean water melts all contacting terminus ice, undercutting the glacier at the waterline and facilitates iceberg calving, or breaking off more icebergs (Figure 2c,d). This removal of terminus ice decreases the amount of ice that the glacier has to move, thereby also leading to increased glacier velocities due to a decrease in back pressure (Figure 2e). 

While two distinct scenarios are presented above, a combination of mechanisms most often controls glacier acceleration. For example, recent studies in Greenland have shown that ocean warming has been the controlling mechanism in glacier instability while in Svalbard both ocean and air temperatures appear to balance each other in driving glacier change.

However, how quickly the Southern Patagonian Icefield is responding to warmer conditions and the primary mechanisms behind ice mass loss remain important questions to be addressed, that Scott’s project will hopefully illuminate over time.