Results from recent ice core discoveries suggest that climate can change in as little as decades—not the tens of thousands of years believed not so long ago. In addition, over one-third of humans (almost 2.4 billion people) live within 100 km (60 miles) of an ocean coast.

 Why is it important to understand how melting ice might affect humans?

All around the world, scientists are measuring the amount of ice that is melting each year. They are learning that almost all glaciers are retreating and that Arctic sea ice melts more during the summers than is reformed during the winter. Because the open ocean water in the summer absorbs heat, it causes what is known as a “positive feedback” loop: more ocean water—more heat—more heat—more melt—more melt—more open ocean water. Scientists expect that we will see an ice-free Arctic Ocean in the summer perhaps as soon as 2030-2050.

The ice sheet in Greenland is also melting and is showing signs of accelerating. In the Southern Hemisphere, Antarctica has ice sheets on land, floating ice shelves and sea ice like the Arctic Ocean in the north. How will melting ice affect our coastlines and sea level?

Key Concepts

There are many different types of ice on Earth:

–Ice that floats: icebergs, sea ice, ice shelves

–Ice that is land-based: glaciers, snow on mountains, ice shelves, ice caps


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