Unit information: Ice and Ocean in the Global Carbon Cycle in 2016/17

Unit name	Ice and Ocean in the Global Carbon Cycle
Unit code	GEOG30014
Credit points	20
Level of study	H/6
Teaching block(s)	Teaching Block 2 (weeks 13 - 24)
Unit director	Professor. Anesio
Open unit status	Not open
Pre-requisites	There are no pre-requisites but students will be offered a revision lecture in the first week to cover material from GEOG25040 Cryosphere 2 that is relevant, as well as additional reading.
Co-requisites	Available to year-three Geography and year- four Geography with Study Aboard/Continental Europe students only.
School/department	School of Geographical Sciences
Faculty	Faculty of Science

Description including Unit Aims

The unit aims to give students a full understanding of the major biogeochemical and microbiological processes that prevail in ice sheets and oceans, with an emphasis on wider global impacts and the links between ice to the surface of oceans and from the surface to the bottom of the oceans. The initial part of the course will cover elements of microbiology and how knowledge of species diversity can be useful to the understanding of biogeochemical processes. In particular, it considers the relatively recent idea that ice sheets and the cryosphere more generally can be considered as a “biome”. Thereafter, the unit includes topics such as the impact of future climate change on ice sheet delivery of nutrients to the oceans, alongside implications of climate warming for ice-sheet ecosystems and ocean biogeochemical cycles. The Ocean component will include description of the solubility pump and biological pump, global estimates, controlling factors and ocean basin differences (e.g. comparing North Atlantic, Southern Ocean and subtropical gyres), latitudinal gradient, role for ecosystem functioning and services, climate impact (loss, adaptation), last Glacial Maximum case study: the lacking CO₂ sink and the iron hypothesis. Those will be linked to fundamentals (e.g. underlying thermodynamics, construction of Bjerrum plot etc) and impacts (ocean acidification, future ocean CO₂ uptake, deep time shallow water carbonate precipitation), definition, importance of sediments for the global C cycle and climate, transport and reaction processes, primary and secondory redox reactions, benthic-pelagic exchange, local and global patterns, temporal variations importance for global biogeochemical cycles and climate, mechanisms and controls on organic matter degradation and preservation, temporal and spatial variability, mechanisms of carbonate dissolution/precipitation and burial, temporal and spatial variability. Links between processes in subglacial systems and the bottom of the ocean will be done by exploring our understanding of life at and below the energy minimum (free energy required to phosphylate ADP to ATP), importance (e.g. CH₄ hydrates, stability of paleoproxies, reconstruction of paleoenvironments).

Discussion of data from field measurements, numerical modelling and laboratory studies are a major theme of the unit.

Structure and content (including sub-elements)

Element 1: Ice Sheets and global biogeochemical cycles (9 lectures, 3 hrs practical)

1. Linking measurements of microbial diversity and biogeochemical functions in ice and oceans
2. Microbial communities on ice sheet surfaces
3. Microbial communities beneath ice sheets
4. Microbial communities in subglacial lakes
5. Carbon sequestration upon ice sheets surfaces
6. Export of organic carbon to downstream Arctic ecosystems
7. Anoxic processes beneath glaciers and ice sheets
8. Antarctic Ice Sheet as a source of iron to the Southern Ocean
9. Biogenic gas production beneath ice sheets

3 hr practical for this element looking at molecular datasets/bioinformatics

Element 2: Carbon cycling in the Oceans (8 lectures)

1. Introduction to the global ocean carbon cycle
2. Ocean productivity and export of organic carbon to the deep ocean
3. Ocean biodiversity and marine ecosystem services
4. Investigating changes of the ocean carbon cycle in the past
5. The Ocean Carbonate System
6. Early Diagenesis
7. Carbon preservation & burial in marine sediments
8. The Deep Biosphere

Intended Learning Outcomes

On completion of this Unit students should be able to:

• Apply an earth systems science approach within any environmental context
• To use a spreadsheet package to perform advanced databases of phylogenetic information to assess what types of microbes are present beneath glacier and ice sheet environments and what is their function. They will also be able to relate this to key in situ biogeochemical processes
• Be able to think critically and formulate ideas about the functioning of an environmental system using a field dataset
• Appreciate the limitations and assumptions made in inferring environmental processes from a field and numerical modelling datasetseld dataset
• Demonstrate an in depth understanding of hydrological biogeochemical and physical processes operating in a glacier system within ice sheets, together with interactions with other components of the Earth system

The following transferable skills are developed in this Unit:

• Numeracy
• Geochemical calculations
• Research design and techniques
• Analytical skills and problem solving
• Computer literacy.

Critical evaluation of literary sources

Teaching Information

Lectures & practical sessions

Assessment Information

Final Exam 67% Project Report 33%

Reading and References

Gaidos, E. et al. (2009), An oligarchic microbial assemblage in the anoxic bottom waters of a volcanic subglacial lake, ISME J, 3: 486-497.

Siegert, M. J., M. Tranter, J. C. Ellis-Evans, J. C. Priscu, and W. B. Lyons (2003), The hydrochemistry of Lake Vostok and the potential for life in Antarctic subglacial lakes, Hydrol Process, 17(4), 795-814.

Wadham, J. L., M. Tranter, M. Skidmore, A. J. Hodson, J. Priscu, W. B. Lyons, M. Sharp, P. Wynn, and M. Jackson (2010), Biogeochemical weathering under ice: Size matters, Global Biogeochem. Cycles, 24(3), GB3025.

Wadham, J. L., M. Tranter, S. Tulaczyk, and M. Sharp (2008), Subglacial methanogenesis: A potential climatic amplifier?, Global Biogeochem. Cycles, 22(2), GB2021.