How are
people changing
the climate?

Basics

1. Man-made climate change?

Worksheet 3

1. Answer individually or in groups

In great forest fires, an enormous number of trees burn, and such fires lead to great amounts of CO₂ being released. Despite this, we do not expect that forest fires increase the greenhouse effect.

Just as trees, fossil fuels are also natural substances. Explain why it is so that burning of these two natural substances, both with release of CO₂, are different in a climate context.

2. Experiment: 
Melting sea ice

a) Put an ice block in a water bath. Make hypotheses about the water level when the ice block melts: Will it be higher, lower or steady state? Observe the water level after the ice has melted. Was your hypothesis confirmed? (Do you know a physical principle that can account for what you observed)?

b) Repeat the experiment, but this time put a pebble/small rock in the water container (the rock must extend above the water level). Place the ice block on top of the pebble. Make hypotheses about the water level when the ice block melts: Will it be higher, lower or steady state? Observe the water level after the ice has melted. Was your hypothesis confirmed?

c) Which of the experiments in a) and b) is a model of the conditions around the North Pole and the South Pole, respectively? Can you use these experiments to deduce something about what happens to the sea level if the ice at and near the North Pole and the South Pole starts to melt?

3. Experiment: 
Thermal expansion

Fill a test tube with coloured water. Put on a rubber cap with a glass tube. Place it in a hot bath. What do you think will happen?

Observe your system for a few minutes. What do you see? Was your hypothesis confirmed? Can you use your observation to say something about the sea level in a warmer climate?

---

Authors: Ellen K. Henriksen and Camilla Schreiner - University of Oslo - Norway. Scientific reviewer: Andreas Tjernshaugen - CICERO (Center for International Climate and Environmental Research - Oslo) - Norway - 2004-01-20 Educational reviewer: Educational reviewer: Nina Arnesen - Marienlyst school in Oslo - Norway - 2004-03-10. Last update: 2004-03-27.