Find out about sea and land ice and what may happen to sea levels if they melt.
Sea Ice and Land Ice
Sea ice is frozen ocean water. It forms, grows, and melts in the ocean. For most of the year, sea ice is typically covered with snow. It covers about 7% of the Earth’s surface and about 12% of the world’s oceans. Find. out more about Sea Ice here.
Land ice in the form of glaciers and ice sheets contains the majority of the world’s fresh water and covers about 10 percent of the world’s land area. Every continent apart from Australia has some amount of land ice, but the large majority of it exists on Greenland and Antarctica.
Exploring Melting Ice
1. Fill each cup three quarters full of water, and float an ice cube in one to represent ‘sea ice’ that
is naturally occurring.
2. Place the funnel in the top of the second cup, and fill the funnel with three ice cubes to represent ‘land ice’.
3. Wait for about an hour to give the ice a chance to melt, then compare the water levels in the cups. Which one is most full and why?
The Danger of Melting Land Ice
What is happening, and how does this mirror what happens in the real world?
Sea ice naturally shrinks in the summer and grows in the winter – but since 2000 scientists have noticed that it s shrinking more and more in the summer and coming back a tiny bit less in the winter, so overall it is reducing. Melting sea ice does not cause sea levels to rise, because it is already in the water so its volume is accounted for.
Melting land ice adds to the volume of water in our oceans so it does cause sea levels to rise. If all land ice melted, sea level would rise approximately 70 meters (230 feet) worldwide. Land ice is melting – according to NASA satellite images, both Antarctica and Greenland are losing land ice. Antarctica has lost more than 24 cubic miles of land ice per year since 2002. Other areas have also seen recent dramatic glacial retreat, including Mount Kilimanjaro (which lost about 80 percent of its glacial ice in the past century), Alaska and the Himalayas.
Take it further
This activity doesn’t take long, but it makes a good starting/finishing activity as it’s good to set up the demonstration and then do something else to allow the ice time to melt. Perhaps pair it with Water Everywhere.