Lecture 1 - Valley Glaciers and the state of the system

Introduction to Glacial Systems

Course convener: Peter Wynn
Rationale for studying glacial systems: They are crucial regulating agents of planet Earth.

Climate Interaction: Glaciers respond to and drive climate.
- The Earth's climate would be different without glaciers and ice sheets.
Sea Level Regulation: Glaciers store fresh water; melting raises sea levels.
- This is a critical issue today.
Ocean Current Influence: Fresh water from melting glaciers changes the balance of ocean currents, affecting heat distribution.
Freshwater Source: Glaciers provide fresh water for drinking and regulate rivers and downstream ecology.
Nutrient Provision: Glaciers contain nutrients like nitrate, phosphate, and silica, which fuel downstream ecosystems.
- These ecosystems wouldn't exist as we know them without glaciers.
Overall: Glaciers are regulating agents in the Earth system.

Lecturers: Peter Wynn, Katie Miles, and Hugh Tuffin.
Week 1: Valley glaciers and their current state.
Weeks 2-4 (Katie Miles): Ice sheets, their location, and current state. Mechanics including mass balance, energy balance, and thermal regime (warm vs. cold ice), supraglacial and englacial hydrology.
Weeks 5-7 (Peter Wynn): Practical session, hydrology at the bed of a glacier, ice dynamics, glacial hydrochemistry, and glacial ecosystems.
Week 8 (Hugh Tuffin): Glaciers and volcanoes with case studies from Iceland and Antarctica.
Weeks 9-10: Climate change impact on the cryosphere.
Flexibility: Student input is welcome to tailor the course content.

Lectures: 14 lectures over ten weeks.
Practicals: Use data sets to explore concepts from lectures in-depth.
- Involve running models in Excel.
Seminars: Reading a paper in advance for in-depth discussion linked to lectures.
- Example: Article provided via Moodle for Week 3 seminar.
Drop-in Sessions: Weekly sessions for asking questions.
Moodle Discussion Forum: For asking questions online.
Direct Contact: Email or office visits to lecturers.

A huge body of ice, millions of square kilometers, unconstrained by topography.
Changes the topography, causing isostatic depression (sinking of the landscape due to mass).
Plays a huge role in regulating climate: fresh water release, sea level rise, blocking air mass movements, creating temperature gradients, driving wind systems.

Valley Glacier: Example: Franz Josef Glacier in New Zealand, flowing into a temperate zone.
Cold Cirque Glaciers: Found in places like the Lake District, forming tarns (lakes) in corrie hollows (cirques or coombs).
- Alpine environments involve corries connecting to main glaciers.
Hanging Glacier: Example: Kumbu Himal in Nepal.
Niche Glaciers: Small glaciers high in mountains, like in Iceland (Sveinafetla).
Floating Glacier Tongue: Moves quickly. Example: Kronerbrane in Svalbard.

Two requirements: Snow and survival of snow through summer melt season.
Snowpack: Accumulation of snow layers; dark layers are dust accumulated in summer.
Metamorphosis: Snow changes to granular ice, then to firn (one-year-old ice), and finally to clear glacier ice as air pockets are squeezed out.
Movement: Once a critical depth is reached and the overburden pressure is great enough, the ice begins to move and deform, becoming a glacier.

Two Key Controls: Latitude and Altitude.
Latitude: Low solar angles at high latitudes (poles are cooler). High solar angles in tropics (fewer glaciers).
Altitude: Adiabatic lapse rate causes temperatures to decrease with altitude.
High-altitude glaciated environments (e.g., the Alps).
Polar environments: Glaciers come down to sea level.

Aspect: Northern side of mountains cooler (more glaciation in Northern Hemisphere).
Relief: Steep slopes may prevent snow accumulation.
Distance from moisture source: Coastal locations have more snowfall and larger glaciers.

Alaska, Central and South America, Scandinavia, Central Europe, Russian Glaciers, Chinese Glaciers, Middle Eastern Glaciers, New Zealand Glaciers.
Approximately 70,000 glaciers covering 250,000 square kilometers.
Potential sea level rise of 87 millimeters if all melted.

Global Mass Change: Most areas losing mass, especially Alaskan and South American glaciers (Zemp et al, 2019).
Change Over Time: Turning point around the 1990s, with most glacierized regions showing declines in mass (IPCC report).
Greenland: Periphery glaciers losing mass since before 2000.
The Arctic region has been negative for a while.

Mass loss from valley glaciers is equivalent to sea level rise from the Greenland ice sheet.

What is a glacier vs. an ice sheet?
How do glaciers form?
Where are glaciers distributed and what determines this?
How have glaciers been changing in mass?
What are the impacts, especially on sea level, water resources, and ecosystem dynamics?