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Glaciers - Key to Understanding Global Climate Change

Glaciers play a crucial role in understanding climate change on a global scale as they are related to all five Earth's systems. They provide important records of past atmospheric changes and represent significant time periods in Earth's history. This article explores the origin of ice, erosional and depositional processes, and the impact of glaciations on the environment. It also discusses the Milankovitch Orbital Theory and the cyclic nature of glaciations.

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Glaciers - Key to Understanding Global Climate Change

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  1. Glaciers- Important in understanding global scale climate change Related to all 5 of the Earth’s systems Exosphere- changes in the amount of sunlight cause glaciations Hydrosphere- glacial ice is frozen water, part of the hydrosphere Geosphere- Glacial ice flows over and modifies land Atmosphere- alteration of global atmospheric patterns contributes to glacial ice formation Biosphere- ice displaces animals and plants

  2. Importance • Glacial times represent significant time • Glacial times represent significant time periods in Earth's history periods in Earth's history Proterozoic, Pennsylvanian, Pleistocene • Represent major climatic departures • Represent major climatic departures from the modern on a Global Scale from the modern on a Global Scale • Cyclic in Nature • Cyclic in Nature • Man's Influence??? • Man's Influence??? • Glacial Ice contains records of past • Glacial Ice contains records of atmospheric changes atmospheric changes

  3. Origin of ice

  4. Response of a Glacier to Changes in Glacial Budget If accumulation = ablation, then no advance or retreat, but continues to flow If accumulation > ablation, then glacier advances while flowing If accumulation < ablation, then glacier retreats, but continues to flow

  5. Erosional Processes Erosional Processes ･ ･ Important erosional Important erosional processes associated processes associated with glaciers include with glaciers include plucking, abrasion, and plucking, abrasion, and bulldozing. bulldozing. ･ Plucking and abrasion ･ Plucking and abrasion are most common are most common > can form a landform > can form a landform called a roche called a roche moutonnee moutonnee

  6. Erosional features Roche Moutonnée

  7. Erosional features • Hanging Valley • Horn • Arete • Cirque • U-shaped trough • Col • Truncated Spurs

  8. Glacial Deposits Glacial Deposits • glacial drift- A general term • glacial drift- A general term referring to sediment formed by refering to sediment formed by any Anyglacial action. glacial action. • Till (Diamicton) poorly sorted, • Till (Diamicton) poorly sorted, unlayered material directly unlayered material directly deposited by a glacier; ice contact deposited by a glacier; • Stratified drift (Outwash) sorted, • Stratified drift (Outwash) sorted, layered sediment usually layered sediment usually deposited by meltwater streams. Proglacial or ice contact deposited by meltwater streams.

  9. Depositional features- glacial erratic A glacial erratic 6 ft Yellowstone Park

  10. Sediments- Glacial Till exposed in Iowa

  11. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  12. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  13. Depositional features- moraines Moraine formation- made of Till, deposited by ice

  14. Lateral Lateral moraines moraines Medial Medial moraines moraines ･ ･ Lateral and Medial Lateral and Medial Moraines are sediment Moraines are sediment eroded from the valley eroded from the valley sides and deposited by sides and deposited by a glacier. They often a glacier. They often appear as dark stripes appear as dark stripes in a glacier. in a glacier.

  15. Depositional features- distribution of moraines

  16. Depositional features- Kames, eskers, kettle lakes, drumlins, outwash plain (sandur)

  17. Depositional features- Kames, eskers, kettle lakes, drumlins, outwash plain (sandur)

  18. Outwash with kettles moraine Kame terrace Outwash Kettle lakes

  19. Outwash Plain with eskers and a braided stream

  20. Pleistocene Glaciations Pleistocene Glaciation • The Pleistocene "ice age" began • The Pleistocene "ice age" began ~1.96 million years ago ~1.96 million years ago • Several glacial and interglacial • Several glacial and interglacial Episodes have occurred. episodes. > Glacial - a period of ice advance, generally > Glacial - a period of ice advance, generally interpreted as a globally cool period. interpreted as a globally cool period. > Interglacial - a period of ice retreat, generally > Interglacial - a period of ice retreat, generally interpreted as a globally warm period. interpreted as a globally warm period. We are in an interglacial period right now

  21. Milankovitch Orbital Theory Milankovich Orbital Theory • Proposed to account for the cyclical • Proposed to account for the cyclical nature of Glaciations. nature of Glaciations. • Astronomer & Mathematician Milutin • Astronomer & Mathematician Milutin Milankovitch attributed the glaciation to Milankovich attributed the glaciation to variation in three parameters of the variation in three parameters of the Earth's orbit. Earth's orbit.

  22. Obliquity- not shown eccentricity precession

  23. warm warm cold cold 1 3 4 5

  24. Erie Lobe

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