Name: 氣候101：冰川｜國家地理頻道 (Climate 101: Glaciers | National Geographic)
Uploaded: 2021-01-14T11:03:53.000Z
Duration: 4 min 6 s
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glaciers are disappearing, not only altering the landscapes

they leave behind, but changing our oceans, weather,

A glacier is a huge mass of ice that moves slowly over land.

Glaciers can be classified into two general groups

Sometimes, they create valleys by pushing dirt, soil,

As ice sheets spread, they cover everything around them

with a thick blanket of ice, including valleys,

The largest ice sheets are called continental glaciers.

They cover vast area including most of Antarctica

Soon after falling, the snow begins to become denser

When new snow falls and buries the previous years snow,

the bottom layer becomes even more compressed.

When the ice grows thick enough, the firn grains fuse

The glacier may begin to move under its own weight,

through a process called compression melting.

As they move, glaciers erode or wear away

less than 20,000 years ago, they left behind

Glaciers provide people with many useful resources.

Glacial till provides fertile soil for growing crops.

And, deposits of sand and gravel are used

Many rivers are fed by the melting ice of glaciers.

Earth's average temperature has been increasing

Glaciers can act as indicators of global warming

Melting ice sheets contribute to rising sea levels.

As ice sheets in Antarctica and Greenland melt,

they raise sea levels, adding fresh water

The loss of glacial ice also reduces the amount

of fresh water available for plants and animals on land.

the ocean ecosystem, as well ocean currents.

Additionally, less salt in the ocean could disturb

Since glaciers are so sensitive to climate change,

is an early warning system for the rest of the planet.

And if global warming goes unchecked, many, if not all,

alpine glaciers could disappear completely.

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氣候101：冰川｜國家地理頻道 (Climate 101: Glaciers | National Geographic)

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