There are two warnings about melting ice and rising oceans: one is by land, the other, by sea. But it’s ice sheets on land, not icebergs in the ocean, that are the biggest contributors to sea level rise.
Land ice includes mountain glaciers and ice sheets, covering Greenland and Antarctica. These giant blocks of ice are melting and the water is flowing rapidly into the oceans. Think of it like adding water to an already full glass — it soon overflows. But melting sea ice behaves differently. Axel Schweiger is a researcher at the University of Washington.
SCHWEIGER: “Melting sea ice has no impact on sea level rise because it’s already floating in the ocean.”
Think of as like a glass of ice water. As it warms, the ice in the glass melts, but the total volume of water does not change. However, melting sea ice does contribute to climate change. That’s because white sea ice reflects the sun. So when it melts, the dark open ocean now absorbs sunlight and heats up, raising global temperatures, which in turn cause glaciers and ice sheets on land to melt further. Globally, sea levels have risen four to eight inches since the last century and will continue to rise as the ice melts, putting coastal communities worldwide at risk.
Reporting credits: David Appell and ChavoBart Digital Media.
Photo: The Antarctic Ice Sheet covers an area larger than the U.S. and Mexico combined. This photo shows Mt. Erebus rising above the ice-covered continent. (Ted Scambos & Rob Bauer) Courtesy of the National Snow and Ice Data Center, University of Colorado, Boulder.
In this lab, students explore this phenomena using a simple lab set up.
Materials (for each group)
I begin this class with a thought experiment by asking students to think about the following scenario, then write a response in their journals before turning and talking to a neighbor about their ideas.
The Too-Full Glass of Water
Show the image below while you narrate the story:
"You place four ice cubes into a glass and fill it with cold tap water to the brim. Using an eyedropper or spoon, you add even more water to make the glass as full as possible.
Predict what you think will happen as the ice melts. Will the glass overflow? Why or why not? Write down your prediction and explain your thinking. "
Below is an image of the experimental set up. We were able to use snow in place of ice.
In the image below you can see the results a student got using compacted snow. Notice the rate of melt of sea ice versus land ice and the corresponding ending water levels.
Wrap up this lesson by asking students to read and answer questions related to the reading. See the attached handout on melting ice.
This reading helps to drive in home the change in glaciers and connect this melting ice to sea level rise. Since we are talking about the inputs and outputs of a system and the relationship of the parts to the outcomes, this is a great opportunity to have students build causal loop diagrams.
Causal loop diagrams help students make connections between elements in a story and identify the relationships between each of the elements.
I have included a link PBS Learning Media's page on Understanding Causal Loops, a great place to start learning the basics of Systems Thinking.
I have students share out their causal loop diagrams with the class. In the image below, one of my students is sharing her diagram.
Below are images of student completed work: