iC3 in Greenland: uncovering the hidden carbon and nutrient cycles beneath melting ice and their impact on downstream ecosystems

As Greenland’s ice sheet retreats, it transforms the landscape and releases materials that can influence ecosystems and the climate. Researchers at the iC3 Polar Research Hub investigate how carbon, nutrients and greenhouse gases move from beneath the ice into lakes, rivers and the ocean.

Greenland’s melting ice sheet is more than a cause of rising sea levels. Glacial meltwater transports nutrients and evacuate greenhouse gas into downstream environments while sediments beneath the ice may store substantial quantities of carbon. How these materials influence ecosystems and the global carbon cycle remain poorly understood.

Figure: iC3 research locations in Greenland.

Following nutrients and carbon from ice to ocean

Jon Hawkings investigates how glaciers mobilise and transport nutrients and organic carbon and seeks to understand how these materials affect downstream ecosystems and global biogeochemical cycles. His research helps establish how Greenland’s changing ice sheet influences the movement of essential elements through the environment.

Credit: Jon Hawkings.

Methane in newly formed lakes

As glaciers retreat, proglacial lakes form and expand across Greenland. These lakes may become important sources of methane, a potent greenhouse gas.

Joost van Genuchten and Guillaume Lamarche-Gagnon study carbon cycling and methane emissions in these lakes. During field campaigns near Kangerlussuaq, Sermilik, and Zackenberg in Greenland, the team has collected lake water, gas and sediment samples to investigate the processes controlling methane production and consumption. Their findings show that lake sediments can contain high microbial methane concentrations despite low organic-carbon concentrations, suggesting these environments may be an overlooked methane source, and hold clues to help us understand how methane can accumulate beneath the ice sheet.

Picture: Joost van Genuchten and Guillaume Lamarche-Gagnon sampling a lake in Greenland. Credit: Emeric Babut du Marès.

Mapping carbon hidden beneath the ice

Not all of Greenland’s carbon is found in its lakes and meltwater. Large quantities may also be stored in sediments beneath the ice sheet, accumulated over thousands of years or longer.

Henry Patton uses machine learning and geophysical datasets to map the distribution of subglacial sediments and estimate their potential carbon stores. Field campaigns drilling through the ice sheet also provide sediment samples to investigate biological processes and methane production beneath the ice. Understanding these hidden reservoirs is essential for assessing how ice-sheet retreat could expose or release carbon in a warming climate.

Credit: Henry Patton.

From Greenland’s ice sheet to its fjords

iC3’s research extends beyond the ice sheet margin. Through the GoNorth 2024 expedition, researchers expanded their work into Independence Fjord in North Greenland. Water-column observations, biogeochemical analyses and sediment records will help reveal how carbon and environmental signals travel through Greenland’s marine systems, connecting the ice sheet to the coastal ocean, how this has changed over timeand what it means for our future.

From field samples to laboratory analysis

Back in Tromsø, iC3 researchers use specialised facilities to investigate the samples collected in the field. The PolarMAGIC laboratory supports microbiological and biogeochemical research through chemical analyses, microbial studies and low-temperature experiments. The new PlasmaLab will expand these capabilities with advanced trace-element and isotope analyses of water, ice and sediment samples, helping researchers trace the movement of elements and reconstruct past environmental changes.

Connecting ice, water and ecosystems

Together, these research efforts connect processes beneath the ice to the lakes, rivers and ecosystems beyond it. By investigating Greenland’s hidden carbon and nutrient pathways, iC3 researchers are working to improve our understanding of how a changing cryosphere may influence the climate system.

Get in touch with our researchers

Jon Hawkings is a researcher investigating how glaciers mobilise and transport nutrients and carbon, and their effects on downstream ecosystems and global biogeochemical cycles. He is based at the University of Pennsylvania. Within iC3, he is part of Research Unit 2: Methane, nutrients and carbon. To find out more about his work, please check out his interview, his list of publications, or contact him by email.

Henry Patton is a researcher working on carbon storage in subglacial sedimentary basins, based in the Department of Geosciences at UiT The Arctic University of Norway, Tromsø. Within iC3, he is part of  Research Unit 1: Carbon and ice sheets. To find out more about his work, please check out his interview, his list of publications, or contact him by email.

Joost van Genuchten is a PhD student working on methane dynamics and carbon cycling in Greenland’s proglacial lakes, based at UiT. He is part of Research Unit 2: Methane, nutrients and carbon. To find out more about his work, please check out his interview, his list of publications, or contact him by email.

Guillaume Lamarche-Gagnon is an environmental microbiologist and biogeochemist, with interests in understanding the interplay between the biological, geological, and hydrological interfaces within the cryosphere. Within iC3, he leads Research Unit 2: Methane, nutrients and carbon. He is based at UiT. To find out more about his work his list of publications, or contact him by email.