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What is glaciology? - ANSWER The study of glaciers and glacial environments. Where do glaciers occur? - ANSWER Polar regions, high mountains e.g., Himalayas, tropical glaciers e.g., Kilimanjaro, and other planets e.g., Mars polar regions. Where did glaciers occur at lower latitudes in the past? - ANSWER South Wales. How fast do ice streams and outlet glaciers move? - ANSWER 1000+ meters per year. How fast do ice divides move? - ANSWER Around 1 meter per year. What is an ice shelf? - ANSWER Ice sheets spilling into the sea, mostly in Antarctica, producing large icebergs.
up to 750m thick
flat upper surface
ice is fast moving How much do mountain glaciers and ice caps contribute to sea level rise? - ANSWER 0.32 meters worldwide. How much could Greenland and Antarctica contribute to sea level rise? - ANSWER 65 meters. What is a mountain glacier? - ANSWER A constantly flowing mass of ice in high mountains where snow accumulates and flows downhill under its own weight.
melts in summer
30-700m per year
carve U-shaped valley E.g., mer de glace What is a valley glacier? - ANSWER Long, narrow glacier flowing down a mountain valley (orignally carved by a river).
10-1000m per year What is a piedmont glacier? - ANSWER when one or more glaciers flow out of mountains and spread onto flat plains at the base of the mountain range.
10-300m per year
What is a tidewater glacier? - ANSWER Valley glacier that reaches the sea, melting and calving icebergs.
100-2000m per year What is a cirque glacier? - ANSWER Small glacier forming in a bowl-shaped hollow high on a mountain.
10-1000m per year E.g., cirque de gavarnie What is an ice cap? - ANSWER large, dome-shaped ice mass under 50,000 km², covering highlands or mountains.
spread in all directions
thickest in the centre
10-1,000m per year Why are glaciers important? - ANSWER. Contain 70% of freshwater
. Regulate sea levels . Climate indicators . Create ecosystems . Scientific and historical records e.g., past climate and atmospheric data What are icefalls and avalanches? - ANSWER Glacial hazards that can bury people and villages. What are glacial lake outburst floods (glofs)? - ANSWER Sudden floods from meltwater trapped behind moraines or ice walls. What are jokulhlaups? - ANSWER Volcanic glacier floods caused by volcanic activity melting ice beneath glaciers. What are glacial surges? - ANSWER Sudden glacier speed-up, pushing ice and debris rapidly downslope. How do glaciers affect sea levels? - ANSWER Melting glaciers contribute to coastal flooding. What lives on the glacier surface? - ANSWER Snow algae Bacteria Microscopic fungi What lives in englacial and subglacial zones? - ANSWER Microbes in pockets of water using minerals for chemosynthesis. What occurs in the proglacial zone? - ANSWER Meltwater streams create new habitats as glaciers retreat.
What is the ablation zone? - ANSWER Lower, warmer glacier parts where yearly melting exceeds snowfall. What are methods of ablation? - ANSWER Melting Sublimation - > ice directly to water vapour (happens in very cold, dry, windy regions) Calving (icebergs) Evaporation Wind erosion - > remove snow from surface internal/basal melt - > geothermal heat or friction melt ice at glacial bed Ice avalanches. What is the Rhône Glacier case study? - ANSWER A glacier in the Swiss Alps steadily retreating since mid-19th century, accelerated since 1980s due to warming temperatures. How much has Rhône Glacier retreated since 1850? - ANSWER 1.5-2 km - > now 7- 8 km long (2024). How much surface area and ice volume has Rhône Glacier lost? - ANSWER 25% of surface area since 1850 60% of ice volume since the last Ice Age. What is the predicted Rhône Glacier loss? - ANSWER Complete loss by 2100 if warming continues. What are the causes of Rhône Glacier retreat? - ANSWER Increased temperatures Shorter winters Reduced snowfall More cryoconite. What are the impacts of Rhône Glacier retreat? - ANSWER Proglacial lake formation Seasonal water imbalance Loss of alpine habitat Tourism decline. What are management strategies for Rhône Glacier? - ANSWER Covering surface with white geotextile sheets to increase albedo (reduce summer melt 50-70%) and continuous monitoring. What is the selfie stick method in glacier measurement? - ANSWER Uses repeat photography from fixed points to monitor glacier changes over time. What is the geodetic method in glacier measurement? - ANSWER Uses aerial or satellite surveys to measure changes in glacier volume and surface elevation.
What is satellite gravimetry in glacier measurement? - ANSWER Detects mass loss/gain in ice sheets by measuring changes in Earth's gravity field. What is ice flow? - ANSWER The movement of glacier ice downhill due to gravity Whats the typical close-off depth for central Antarctica? - ANSWER 90-120m Whats the typical close-off depth for Greenland interior - ANSWER 60-100m Whats the typical close-off depth for coastal Greenland - ANSWER 40-60m Whats the typical close-off depth for temperate mountain glaciers - ANSWER 20- 40m Process of snow turning to ice - ANSWER snow - > Névé (hours) - > firn (summer) -
ice (many years) Advantages of selfie stick method - ANSWER. Cheap
. Easy for small glaciers . Low skill requirement Disadvantages of selfie stick method - ANSWER. Less precise than GPS or laser scanning . Measures relative change not absolute ice thickness . Hard in poor weather and crevassed areas Whats the poles and tape measure method - ANSWER pole or stake drilled into the ice (deep enough that it won't ablate out) Measure pole depth at different seasons
measure ice thickness which can be extrapolated for the whole of the glacier. Advantages of geodetic method - ANSWER. Covers whole glacier . Accurate for long-term trends . Useful for remote/dangerous glaciers Disadvantages of geodetic method - ANSWER. Requires high quality dems . Can't easily capture seasonal mass balance . DEM errors if misaligned or snow variations Advantages of satellite gravimetry - ANSWER. Measures total mass change . Can cover remote/dangerous glaciers . Useful for large ice sheets Disadvantages of satellite gravimetry - ANSWER. Coarse resolution - > can't do small glaciers
What does higher strain rate = - ANSWER faster ice flow Increase driving stress = - ANSWER much faster ice flow Thicker glacier = - ANSWER more driving stress - > faster flow Steeper slope = - ANSWER more driving stress - > faster flow Higher temperature = - ANSWER faster flow Where is stress and strain the highest? - ANSWER at the bed Where is deformation the fastest - ANSWER bed How do glaciers move - ANSWER each layer carries the layer above it Why do glaciers exist if ice melts at 0°C? - ANSWER The weight of the glacier increases pressure, reducing the melting point (~0.0072°C per bar). The base can reach its melting point even if the rest is frozen. - > causes sliding. Why is the internal temperature of a glacier usually below freezing? - ANSWER Deeper ice is insulated from surface warmth. How do high altitudes or latitudes influence glacier melt? - ANSWER Annual temperatures usually stay below 0°C, so only the top few cm-m melt in summer, with accumulation replenishing melt. What is the cryosphere? - ANSWER All frozen parts of the Earth system. What is cryoconite? - ANSWER Windblown dust and organic material that collects in small holes on glaciers, forming dark patches that absorb heat and melt ice. What is cryoturbation? - ANSWER Mixing of soil caused by freeze-thaw processes. What is a cryowurst? - ANSWER A cylindrical, wireless glaciology instrument deployed into a borehole that measures temperature, water pressure, electrical conductivity, and orientation.
sends data up wirelessly How much pressure does 1m of water exert? - ANSWER 0.1 bar - > divide by 10 to work out pressure. What is ice density - ANSWER 90% of the density of water
How much does the melting point decrease by per bar of pressure - ANSWER 0.0072°C How do you work out temperature drop - ANSWER ice density x 0.0072°C What is the pressure melting point? - ANSWER The temperature where ice begins to melt under its own weight; varies linearly with depth. Define a temperate glacier. - ANSWER A glacier where the temperature is at the pressure melting point (e.g., alpine glaciers). Define a cold glacier. - ANSWER A glacier colder than the pressure melting point; usually small, thin, frozen to the bed, and moves slowly (polar glaciers). What is a land-terminating glacier? - ANSWER A glacier whose terminus ends on land; loses ice mainly through surface melt. What is a marine-terminating glacier? - ANSWER A glacier ending in the ocean; responds to ocean warming and air temperature and can significantly contribute to sea-level rise. What does supraglacial mean? - ANSWER On top of the glacier. What does englacial mean? - ANSWER Inside the glacier. What does subglacial mean? - ANSWER Underneath the glacier. What does proglacial mean? - ANSWER In front of the glacier. What are sources of water in glaciers? - ANSWER Rainfall Solar radiation Warm air/wind - > increase sensible heat flux - > raise ice surface temperature - > melts What are surface stores of water on glaciers? - ANSWER Ponds Lakes Crevasses Firn aquifers Wet snow. What are firn aquifers? - ANSWER Water-saturated layer of firn within a glacier storing liquid water year-round. How do firn aquifers form - ANSWER meltwater from the surface drains downwards, reaches porous firn and gets trapped - > remains liquid water as insulated by colder firn and snowfall above.
Channel attributes - ANSWER. Water flows fast
. Low water pressure . Short residence time . Efficient drainage Winter on alpine glaciers - ANSWER frozen - > slow movement via ice creep Spring on alpine glaciers - ANSWER melt begins - > meltwater forces its way to the bed - > creates cavity system Glacier lifted by water pressure - > speeds up Summer on alpine glacier - ANSWER loss of meltwater - > rides channels and enlarges moulins Channels connect to moulins - > pressure release to the air Reduced subglacial water pressure Glacier slows down Autumn on alpine glacier - ANSWER meltwater reduces - > moulins and channels close up What is a cryoegg? - ANSWER A small, spherical wireless probe measuring water pressure, temperature, and electric conductivity (shows what dissolved ions it contains) ice. Benefits of cryoegg - ANSWER. Allows the real-time measurements of water conditions inside the ice without risking damage to cables and needing to retrieve the instrument later. . Understanding how water moves under ice sheets/glaciers helps predict ice- sheet stability, glacier retreat, and sea level rise under climate change.
