Introduction

“When the well is dry, we know the worth of water.”
Benjamin Franklin (1706-1790).

As more and more is found out about the effects of global warming on the Earth, the influence that water in the oceans and in the air can exert on weather patterns becomes more apparent. The finite amount of water in, on and around the planet can, if its location or state changes, cause problems for mankind. Scotland has had a very wet Autumn, with more than twice the expected level of rainfall from October to December. This led to widespread flooding, traffic disruption and school closures.

Figure 1a - Global warming - is it a reality?

At the same time, Australia has suffered from its worst drought since records began. Antarctica is the driest continent, and its Polar region only receives about the same amount of moisture as a hot desert. However, the snowflakes that fall there have been accumulating undisturbed for hundreds of thousands of years. Each flake contains information about the dust, gas and chemicals that were in the atmosphere at the time it was created, so it can provide scientists with information on environmental conditions from long ago.

Figure 1b - Climate change published by the RSC, includes a series of activities for students with background information and teaching tips on current climate issues. It brings together several sources of data on the Earth's climate, newspaper cuttings and examines Mario Molina's work on ozone and its impact on global politics. Click graphic on the right for more.

Water is unusual because the three states of matter (solid, liquid and gas) can be shown
to children at easily achievable temperatures. They will be familiar with the solid (ice), the
liquid (water) and can detect the presence of the gas (water vapour) if they breathe on a
cold window or mirror and the invisible gas condenses into liquid water droplets. If you look at the emissions from a boiling kettle, invisible water vapour occupies the space close to the spout. We often think of steam as a cloudy, white “gas,” but that white mist is actually just tiny liquid droplets suspended in the air.

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