In this lesson, we explore glaciation. Referring to the movement and formation of glaciers, glaciation has played an important role in human history, including allowing for the implementation of one of humanity’s most important practices.
Ice, Big and Small
Most people encounter ice on an everyday basis. If you live in southern California, chances are the only ice you ever encounter is the cube form that you place in your water every day, but those of us who live in America’s northern states can assure you: ice is a natural part of the environment, whether you like it or not. Indeed, some of us spend countless hours scraping ice off our car windows every winter morning, or spend our weekends skating on the ice that seals in our northern lakes every year.
While northerners encounter naturally occurring ice outdoors, it’s doubtful that any North Dakotans or Michiganders have ever seen ice’s largest and most powerful formation: glaciers. Glaciers are sheetlike walls of ice that move incredibly slowly. Indeed, the fastest glacier today, the Jakobshavn Glacier in Greenland, moves only 20 meters per day!The term glaciation refers to the movement and formation of these megalithic wintry features. Glaciation is important because, while slow, the actions of glaciers can affect ocean levels, ocean salinity, earth’s reflectivity, and the overall climate over long periods of time.
As such, they have played a pivotal role in human history.
Glaciation in History
The amount and size of glaciers have fluctuated wildly throughout the Earth’s history, with periods of expansion and recession often lasting thousands of years. The most recent glacial period, and the one most important for human history, occurred over nearly 100,000 years in our relatively recent past.Termed the Wisconsin glacial period in North America, the glaciers reached their largest extent about 18,000 years ago when large sheets of ice covered all of Canada, New England, Michigan, and large portions of other northern states.
After this apex, the glaciers retreated relatively rapidly and, 10,000 years ago, most of Canada was free of ice. It’s no coincidence that this period of quick warming and glacier melting corresponds historically with the introduction of agricultural techniques that led to sedentary farming communities, and the development of modern human society. The warming of the Earth and the freeing of land from the walls of ice allowed for human civilization to thrive.
Glaciers still exist and glaciation still occurs today, albeit at a much smaller scale than it occurred thousands of years ago. Glaciers today still cover approximately 10% of the world’s surface, although nearly all of that is contained either in Antarctica or on Greenland; fewer than 5% of the Earth’s total glaciers are elsewhere! Glaciers are still moving and forming, although most are currently in recession due to global warming and other mitigating factors.
Use your knowledge of glaciation to carry out the following actions:
- Define glaciation and note its importance
- Recall the history of glaciation on our planet
- Recognize what is happening to glaciers today