Basics of Glaciers

Summary

This video lecture explores the fascinating world of glaciers. It covers their formation, types, and significance in our planet's climate system. Glaciers, described as 'rivers of ice,' form in areas with persistent snow accumulation, with two main types: alpine glaciers in mountain ranges and continental ice sheets in vast, flat areas like Greenland and Antarctica. The video discusses the anatomy of glaciers, the impact of ice ages, and how climate change is affecting glaciers worldwide. It also highlights subglacial discoveries, such as hidden mountains and lakes, along with their potential ecosystems and ongoing research.

Takeaways

• 😀 Glaciers are often referred to as 'rivers of ice' and form in areas with permanent snow, building up over years to form ice masses.
• 😀 Glaciers cover 11% of Earth's land surface, with past ice ages seeing glaciers cover up to 30%.
• 😀 Glaciers primarily form in two regions: high latitudes (cold areas with low solar insulation) and high elevations (mountainous regions above the snow line).
• 😀 The snow line is the lowest elevation where snow survives year-round, marking where winter snow persists into the summer.
• 😀 Alpine glaciers form in mountain ranges and include types like cirque glaciers, valley glaciers, piedmont glaciers, and tidewater glaciers.
• 😀 Cirque glaciers form in bowl-shaped erosional landforms and can flow downhill, eventually merging into valley glaciers.
• 😀 Valley glaciers are rivers of ice within valleys shaped by previous stream action, and they can merge to form piedmont glaciers, which spread freely over lowlands.
• 😀 Tidewater glaciers flow into the ocean and can calve, breaking off chunks of ice that become icebergs.
• 😀 Continental glaciers, or ice sheets, are much larger than alpine glaciers and form in non-mountainous areas, notably in Greenland and Antarctica.
• 😀 Antarctica holds 92% of Earth's ice, with sub-glacial mountain ranges and large freshwater lakes hidden beneath thousands of feet of ice.
• 😀 Greenland's Jakobshavn Glacier is a significant glacier, known for its recent growth, despite global trends of glacier retreat due to climate changes.

Q & A

What are glaciers often referred to as, and why?

Glaciers are often called 'slow-moving rivers of ice' because they move very slowly and are made up of ice that flows over land, much like a river of water.

How do glaciers form?

Glaciers form in areas of permanent snow, where snow accumulates year after year and eventually compacts into ice. This process continues over many years, eventually forming a mass of ice.

What percentage of Earth's land surface is covered by glaciers today?

Today, glaciers and ice sheets cover about 11% of Earth's land surface.

How much of Earth's land surface was covered by glaciers during past ice ages?

During past ice ages, glaciers covered as much as 30% of Earth's land surface.

What are the two main contexts in which glaciers form?

Glaciers form in high latitudes, where there are very cold temperatures, and above the snow line, which is found in high mountain regions.

What does the 'snow line' refer to?

The snow line refers to the lowest elevation where snow survives year-round. This is the point where snow accumulation persists through the summer without melting.

What are the two basic types of glaciers?

The two basic types of glaciers are alpine glaciers and continental ice sheets.

How do alpine glaciers form, and where are they commonly found?

Alpine glaciers form in mountain ranges, typically within snow fields confined by cirques, which are bowl-shaped erosional landforms. They are commonly found in high mountain regions.

What is a piedmont glacier?

A piedmont glacier is a glacier that forms when multiple valley glaciers merge at the base of a mountain range and spread out over lowland areas.

What is a tidewater glacier, and how does it contribute to the formation of icebergs?

A tidewater glacier flows into the ocean, and when pieces of ice break off from the glacier into the ocean, it creates icebergs. This process is called 'calving.'

What are continental glaciers, and where are they primarily found?

Continental glaciers, or ice sheets, are much larger than alpine glaciers and form in non-mountainous areas. They are primarily found in Greenland and Antarctica.

How thick are ice sheets, and what effect do they have on the land beneath them?

Ice sheets are typically between 5,000 and 13,000 feet thick. They are so heavy that they depress the land beneath them.

What unique discovery was made in Antarctica using radar mapping?

Radar mapping revealed the existence of sub-glacial mountains in Antarctica, known as 'Antarctica's ghost mountains,' which are buried beneath up to 2,000 feet of ice.

What are subglacial lakes, and why are they significant?

Subglacial lakes are freshwater lakes that exist beneath glacial ice. They are significant because they may contain unique ecosystems, and scientists have found microbes living there in the absence of solar energy.

What is the importance of Greenland's Jakobshavn Glacier?

The Jakobshavn Glacier in Greenland is important because it is a massive glacier that has experienced both retreat and recent growth. Calving from this glacier may have been responsible for the iceberg that sank the Titanic.

How is the retreat of glaciers in Greenland related to climate change?

In Greenland, the retreat of glaciers is primarily due to warmer temperatures, which cause melting. However, some glaciers, like the Jakobshavn Glacier, have shown unusual growth due to colder water currents in nearby seas.