Crash Course Geography: Glaciers and Their Impact

Introduction

• Presenter: Alizé Carrère
• Main Topic: Glaciers' role in shaping Earth's landscapes and their indications of climate change.
• Glaciers are large masses of ice formed from compressed snow that move under their own weight.
• Two main types:
  • Alpine/Mountain Glaciers: Found in mountain ranges.
  • Continental Glaciers/Ice Sheets: Continuous mass of ice larger than 50,000 square kilometers.

Glaciers and Climate

• In 2021, 10% of Earth's land surface is covered in ice, primarily in Greenland and Antarctica.
• Glaciers influence climate by reflecting solar radiation (albedo effect), helping keep Earth cool.
• Contains a significant portion of Earth's freshwater; if melted, could drastically raise sea levels (70 meters).
• Historical evidence of ice ages shows glaciers altered global climates.

Ice Ages

• Definition: Periods alternating between glaciations (ice advances) and interglaciations (ice retreats).
• Current period: Interglaciation of an ice age started around 2.5-3 million years ago.
• Glaciers form above the snow line where annual snowfall exceeds melting and evaporation.

Physical Dynamics of Glaciers

• As snow compresses into ice, it becomes denser and capable of movement.
• Large ice sheets move a few centimeters per day; mountain glaciers move faster due to gravity.
• Dynamic equilibrium: When new snow equals the amount melting, glaciers are stable.

Historical Impact of Glaciers

• During the last glacial maximum, large parts of North America, Europe, and South America were covered with ice.
• Moraines: Ridges formed by debris carried by glaciers.
• Features like New York's landscapes (e.g., Central Park's erratics) formed by glaciers.
• Great Lakes and Finger Lakes formed by glacial erosion.
• Mountain glaciers sculpt landscapes (e.g., Matterhorn, Alps).

Present and Future Concerns

• Melting glaciers indicate climate change and potential sea level rise.
• Thwaites Glacier ("Doomsday Glacier") in Antarctica is a critical concern.
• Glacial history reflects human history, influencing agriculture and settlement.

Call to Action

• Learn about and acknowledge the indigenous peoples' relationship with the land.
• Explore resources like nativeland.ca.
• Support educational platforms like Crash Course through Patreon.

Conclusion

• Glaciers continue to shape landscapes and influence global climates.
• Importance of understanding past and future impacts of glaciers on human society.

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• Note: Many place names and borders do not reflect indigenous languages or histories. Crash Course acknowledges this and encourages further learning.