What Are Glaciers? Crash Course Geography #26

Summary

The video explores how glaciers have shaped Earth's landscapes and influenced climate. Glaciers, formed from compressed snow, move slowly and drastically reshape the land by eroding valleys and depositing rocks. They’ve created features like the Finger Lakes, Great Lakes, and the Alps' Matterhorn. Glaciers also act as time capsules, storing climate data from millions of years. As glaciers melt due to climate change, sea levels rise, threatening coastal populations. The video concludes by reflecting on humanity's relationship with glaciers and the potential future impacts of their continued melting.

Takeaways

• 🌍 Glaciers have significantly shaped many of Earth's landscapes, including Ithaca, New York, which features a variety of terrains such as farms, forests, mountains, lakes, and waterfalls.
• ❄️ Glaciers act as indicators of climate change, reflecting the Earth's climatic history and providing insights into its future.
• 🏔️ There are two main types of glaciers: alpine or mountain glaciers, and continental glaciers or ice sheets, which cover about 10% of the Earth's land surface.
• 🌞 Glaciers influence the global climate by reflecting a significant amount of solar radiation, helping to keep the Earth cool.
• 💧 Glaciers contain the majority of the Earth's freshwater, and if they were to melt, sea levels would rise approximately 70 meters, drastically altering coastlines and affecting over 2.4 billion people.
• 🏞️ The British Isles and North German Plains have geological features suggesting they were once covered by glaciers, indicating past global climate changes.
• ⏳ We are currently in an ice age, specifically an interglacial period, which means we are between glacial periods.
• 🗻 Glaciers form above the snowline where snow accumulation exceeds melting, and their movement is influenced by their own weight and gravity.
• 🏗️ Glaciers can dramatically reshape landscapes through both erosion, creating features like the Finger Lakes, and deposition, leaving moraines and erratic boulders.
• 🌿 The retreat of glaciers at the end of the Last Glacial Maximum left behind terminal moraines and influenced the development of cities like New York City.
• 🌊 The potential collapse of glaciers like the Thwaites Glacier could have severe global consequences, including a significant rise in sea levels.

Q & A

What is the significance of glaciers in shaping Earth's landscapes?

Glaciers have been crucial in shaping Earth's landscapes by creating fertile soils and physical features such as valleys, moraines, and erratics. They also serve as frozen time capsules, recording Earth's climatic history and providing clues to its future.

What are the two main types of glaciers?

The two main types of glaciers are alpine or mountain glaciers, which are found in mountain ranges, and continental glaciers or ice sheets, which are unconfined masses of ice larger than 50,000 square kilometers.

How much of Earth's land surface is covered by ice?

In 2021, about 10 percent of Earth's land surface is covered by ice, primarily in the Greenland and Antarctic ice sheets.

How do glaciers influence global climate?

Glaciers influence the global climate by reflecting a significant amount of solar radiation due to their white color, which helps keep the Earth cool. They also play a role in heat transport systems between polar and equatorial regions.

What would be the impact if all the world's glaciers were to melt?

If all the world's glaciers were to melt, sea levels would rise about 70 meters, changing ocean circulation patterns and altering weather and climate in mid-latitudes. This would also lead to political, economic, and social upheaval, reshaping coastlines and affecting over 2.4 billion people living near coasts.

How do glaciers form?

Glaciers form above the snowline where the amount of snow that falls each year exceeds the amount lost through evaporation and melting. As layers of snow get buried and compacted, they turn into ice, and the weight of the glacier reshapes the ice crystals, making them harder and denser.

What is the difference between glaciations and interglaciations?

Glaciations are periods when temperatures drop, and ice sheets grow and spread, while interglaciations are milder periods. An ice age consists of alternating glaciations and interglaciations, lasting for millions of years.

What is a terminal moraine and how does it form?

A terminal moraine is a ridge of debris, such as gravel, sand, silt, and clay, left behind by a glacier as it melts and retreats. It forms at the most forward edge of a glacier and can stretch continuously across regions.

How did glaciers shape New York City?

Glaciers shaped New York City by creating waterways used for trade and commerce and ridges that became easy paths between villages. The city's layout, including Broadway, follows these natural features. The terminal moraine in areas like Brooklyn, Queens, and Staten Island influenced land use, leading to the development of parks and other green spaces.

What are some erosional features created by glaciers?

Glaciers create erosional features such as U-shaped valleys, cirques, aretes, and horns. They also deepen and broaden valleys, creating distinct landscape features like the Finger Lakes and the Great Lakes.

How do glaciers contribute to the formation of mountain peaks like the Matterhorn?

Glaciers contribute to the formation of mountain peaks like the Matterhorn through a process of glacial plucking and abrasion, which carves away at the mountain mass from different sides, creating a symmetrical spire with precipitous rock walls.