For this experiment, we’re setting up an ocean environment and using ice cubes to represent the Arctic sea ice.
What you’ll need:
A large, clear glass or plastic container, like a baking dish or beaker
A jug of water (room temperature)
A tray of ice cubes
Pen and paper
A small plastic cup or container
Optional: blue food colouring, rocks and plastic animals to bring your ocean environment to life.
Pour enough water in the large container to fill it halfway.
Add a few ice cubes to the water. Remember, these are acting as the Arctic sea ice, so make sure they’re floating and not touching the bottom of the container.
Use your ruler to measure exactly how deep the water is and write it down.
You might also like to mark the depth on the side of your container – but check with your parents first!
Wait and watch how the ice cubes change shape as they melt.
Measure the water level when they are melted to half their size.
When the ice cubes are fully melted, use the ruler to measure the final depth of the water.
Write this measurement down on your piece of paper. What do you notice?
You should be getting different results from the two experiments. Do you know why? Before we answer that, we’re going to do one more experiment.
BONUS experiment: Things are heating up
Let’s keep experimenting to investigate one more factor that could be influencing changes in ocean levels – the temperature!
You will need a thermometer to do this experiment. Make sure you ask for help before heating up your water, and don’t carry the hot water by yourself.
Keep using the same container you used in Experiment 1 with the same water.
Use your ruler to confirm the measurement of how deep the water level is and write this down. Use the thermometer to measure the temperature of the water, and write this down as well.
Use a hot water bottle or a heat pack to warm the water. You must have a grown-up help you for this bit.
Use a thermometer to track the changing temperature of the water. Write the temperature down and then measure the depth of the water at different temperatures.
What happens to the water level as the temperature rises?
What does it all mean?
Rising sea levels are one of the clearest signs of global warming. It’s also one of the biggest problems that global warming is causing.
Using the results from your experiments, can you identify the two main causes of sea levels rising? What did we see?
In the experiments, we saw that:
The water level increased when the land ice melted into the water
The water level increased when the water temperature was higher.
What do these two things have in common?
The answer is HEAT.
As our planet becomes warmer, land ice melts and flows into the oceans. More water in the oceans makes sea levels higher.
And as water becomes warmer, it expands (gets bigger) and increases in volume. This is called thermal expansion.
And now we can answer our original question: If melting sea ice is not changing sea levels, then what is?
The answer is… rising global temperatures.
But hold up! If that’s the answer, then why is melting Arctic sea ice so bad?
Arctic sea ice plays an important role in moderating global warming. Its bright surface reflects sunlight back into space to prevent the ocean from absorbing extra solar energy (which would raise temperatures even further). It also plays a role in the movement of ocean currents. And of course, sea ice is an important habitat for animals like the polar bear.