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Ecological Modelling of the Greenland Ice Sheet Surface Ecosystem

Periodic Reporting for period 1 - EMoGrIS (Ecological Modelling of the Greenland Ice Sheet Surface Ecosystem)

Reporting period: 2016-01-01 to 2017-12-31

Glacier ecosystems play significant roles in large-scale physical and biogeochemical processes, and are very vulnerable to the ongoing climate change, with potentially significant impacts. Despite the growing number of studies from glaciers and ice sheets, our understanding of the functioning of glacial ecosystems is far from complete. As a result, predictions of future ecosystem change of glaciers and ice sheets, essential for scientists as well as residents of glaciated countries and policy makers, are virtually impossible.

This project addresses the current absence of a theoretical framework of glacier and ice sheet ecosystems in order to enable their mathematical modelling, predicting their future changes, and using them as model systems for theoretical ecology. The principal aims of the proposed fellowship are the following:

1) To provide a theoretical framework of the supraglacial ecosystem of the Greenland Ice Sheet and to develop a modelling tool for prediction of the future change of the ecosystem. This objective includes the development of a conceptual model, its mathematical formulation and validation, and the application of future scenarios of the ice sheet. Special attention will be paid to identifying feedback mechanisms that could potentially result in runaway processes and further acceleration of the current change of the GrIS.

2) To establish the supraglacial ecosystem of the GrIS as a model system for studying microbial biogeography and diversity patterns. This objective includes the identification of ecologically relevant factors that affect microbial diversity on the surface of the ice sheet, the formulation of hypotheses testable by field experiments and analyses, and the development of a specific sampling strategy that will test these hypotheses.

The project has achieved its main scientific objectives and milestones, and, moreover, the fellowship has enabled me to broaden my research palette and to establish myself as an independent scientist and team leader producing high quality research.
I developed conceptual models of the supraglacial ecosystem of the GrIS, identified and implemented model variables and parameters, and wrote a perspective paper entitled “Ecological modelling of the supraglacial ecosystem: a process-based perspective” published in Frontiers in Earth Science as Milestone 1 of the project. I then constructed a mathematical ecosystem model as a set of OC reservoirs linked via a number of biotic and abiotic OC processes, verified it with respect to its tractability and internal consistency and performed sensitivity tests using realistic ranges of the parameters. Forcing data for surface melt and incident radiation were obtained from the Programme for Monitoring of the Greenland Ice Sheet. I presented the first version of the model (Milestone 2) at the Polar and Alpine Microbiology meeting in Nuuk, Greenland, in September 2017, and will present an improved version at the EGU meeting in Vienna in April 2018. A manuscript describing the model and demonstrating its usefulness in a series of future climate scenario simulations is in preparation as Milestone 3 of the project. The model is constantly being improved by adjusting the parameters according to new data as they become available.

I have introduced the Greenland Ice Sheet into the ecological community as a model system for testing biogeography and diversity patterns hypotheses. A draft project proposal outlining field-based research on the surface of the GrIS and including a spatially explicit field work plan has been produced as Milestone 4 of the project.

I also continued to work on a research project focusing on processes that contribute to the biological darkening of the ice surface in Greenland. I finished the first quantitative assessment of the microbial contribution to the Greenland ice sheet surface darkening (together with my colleagues and co-workers from 14 institutions and 7 countries). We found that the effect of a specific group of algae on bare ice darkening in the study area is greater than that of other impurities, and that incorporating the darkening effect of ice algal growth will thus improve mass balance and sea level projections of the Greenland ice sheet. The results of this project were published in a paper called “Algae drive enhanced darkening of bare ice on the Greenland Ice Sheet” in Geophysical Research Letters and attracted a lot of attention from both the scientific community and the public.
I started exploring a new methodical approach that proves to be very useful in the field of cryosphere biogeoscience. Modelling results show our lack of understanding of some important processes at the surface of glaciers and ice sheets and provide directions for future field and experimental work. Future simulations show the importance of biological processes in cryosphere ecosystems and their dynamics associated with global climate change.

Direct use of the results for policy and decision making was outside the scope of the project, however he significance of this research will hopefully go beyond the realm of science due to its potential use in predictions of the future of glacier ecosystems. The model outputs may be potentially important and useful for residents of glaciated areas and for local policy makers.
Greenland supraglacial ecosystem conceptual model