https:\/\/ucph-ku.zoom.us\/j\/61262559076?pwd=4hq2Nk17h7CorWDVDF8F0GO1hQMCT6.1#success<\/a><\/p>\nSupervisors:<\/strong>
\nAssociate Professor Jesper Riis Christiansen, IGN, Denmark
\nSenior Scientist Christian Juncher J\u00f8rgensen, Aarhus University, Denmark<\/p>\nAssessment committee:<\/strong>
\nProfessor Thomas Alexander Davidson, Aarhus University, Denmark
\nAssistant Professor Andrea Pain, University of Maryland, USA
\nAssociate Professor Aslak Grinsted (Chair), IGN, Denmark<\/p>\nSummary:<\/strong>
\nSubglacial environments beneath glaciers and ice sheets, once thought to be devoid of life, turn out to be highly active ecosystems that harbour both microbial life and significant carbon reserves. These cold ecosystems are also sources of methane,\u00a0 potent greenhouse gas released into the atmosphere by glacial meltwater. The magnitude of these subglacial methane emissions on a global scale is unknown, and therefore, these emissions cannot yet be considered in the global methane budget. Furthermore, there are still large gaps in our knowledge regarding the distribution of emissions between different types of glaciers and which physical, chemical and biological processes affect the magnitude of emissions. As the melting of the world\u2019s glaciers accelerates with global warming, it is crucial to conduct long-term measurements at many locations to understand the eventual climate impact of subglacial methane emissions. This thesis focuses on three key areas that aim to expand our fundamental knowledge by (1) developing sensor technology for measuring methane in meltwater, (2) investigating the temporal dynamics of methane release from an outlet glacier of the Greenland Ice Sheet and (3) exploring potential methane release from different types of glaciers.
\nThe first goal was to design and build a sensor for dissolved methane in meltwater that enables continuous measurements. Furthermore, the goal was that the sensor could be built at a low price and function independently in the field. Field trials demonstrated the accuracy of the sensor with measurements comparable to advanced state-of-the-art devices. It shows the sensor\u2019s potential for continuous measurements, and its low price (~250-300 Euros) makes it possible to spread many units for measurements in multiple glacier systems. In addition, experiments showed that the sensors also work in warmer water environments, such as lakes and streams.
\nThe second objective focused on characterizing methane emissions from a known subglacial methane source at Isunnguata Sermia glacier on the western margin of the Greenland Ice Sheet. Over three melt seasons, continuous measurements showed that the daily and seasonal variations in dissolved methane are driven by the interactions between the subglacial meltwater and methane-producing sediments connected in an evolving drainage system. These results highlight the importance of continuous monitoring to capture the full variability of methane emissions needed to understand how melting and methane emissions are linked.
\nThe third part of this thesis expanded the spatial understanding of methane emissions from other types of glaciers when it was discovered that three glaciers in the Yukon, Canada, emitted methane into the\u00a0atmosphere. These results suggest that subglacial methane emissions are more widespread than previously thought and occur under large ice sheets and smaller mountain glaciers.
\nThe research in this PhD thesis advances the understanding of subglacial methane emissions through sensor development and new field data that highlight a complex interplay between melting and subglacial biological processes and that methane emissions from glaciers are widespread across the globe. The thesis forms the basis for future studies within this new research area.<\/p>\nA digital version of the PhD thesis can be obtained from the PhD secretary at\u00a0phd@ign.ku.dk\u00a0before the defence. After the defence the thesis will become available from the Royal Danish Libary at kb@kb.dk.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"Sarah Elise Sapper defends her thesis, Methane emissions from meltwaters of the Greenland Ice Sheet and mountain glaciers Sensor development, temporal dynamics and occurrences Zoomlink:\u00a0https:\/\/ucph-ku.zoom.us\/j\/61262559076?pwd=4hq2Nk17h7CorWDVDF8F0GO1hQMCT6.1#success Supervisors: Associate Professor Jesper Riis Christiansen, IGN, Denmark Senior Scientist Christian Juncher J\u00f8rgensen, Aarhus University, Denmark Assessment committee: Professor Thomas Alexander Davidson, Aarhus University, Denmark Assistant Professor Andrea Pain, University […]<\/p>\n","protected":false},"author":0,"featured_media":171032,"template":"","class_list":["post-171031","event","type-event","status-publish","has-post-thumbnail","hentry","event_category-phd"],"acf":[],"aioseo_notices":[],"yoast_head":"\n
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