Why are our glaciers shrinking?

Key questions

Who is the iceman and why was he murdered?

What is happening to the world's ice - why is it melting?

How does ice tell us the secret of why it is melting?

Environmental interaction and sustainable development

Who is the iceman and why was he murdered?

The ‘iceman' was found in an Austrian snowfield in 1991. Covered by ice for 5000 years, melting ice revealed his body to explorers. As the ice melted, a man was revealed who had lived long ago, shedding light on his life and finally his violent murder. We now know that when The Iceman's body was discovered, he had with him a copper bladed axe. So rare and expensive was this item that scientists feel that his death could not have been a random attack or his killers would have stolen it. Instead the evidence suggests that his murder was likely to be political. The man's age and weapon indicate he was powerful, and as so little preparation went into his journey it is likely that he left his home in a hurry trying to escape from danger.

The case study shows that the ice has stories to tell. It also gives us a clue that some of the world's ice is melting.

What is happening to the world's ice - why is it melting?

The world's ice is melting, quite simply, as a result of climate change. Rising temperatures in the earth's atmosphere are being caused predominantly by the burning of fossil fuels - coal, oil and natural gas - in the operation of cars, planes, heating and lighting our homes, and so on. This releases carbon dioxide into the atmosphere which acts as an insulating layer - very much like a greenhouse - trapping solar insolation and raising temperatures at the earth's surface. Plants and trees absorb carbon dioxide for the process of photosynthesis, so are natural carbon ‘sinks'. As a result, deforestation contributes to the problem. During the 20th Century, surface temperatures rose on average 1C. As a result of this increase, snow and ice cover has decreased, releasing freshwater into the oceans. In the same timeframe global sea levels have risen between 10cm and 20cm. Without significant policy changes, global mean temperature is predicted to increase between 1.4 and 5.8C over the next century, with an equivalent sea level rise of between nine centimetres and 88cm globally.

In terms of the shrinking of glaciers, the impacts of climate change are being felt most severely at the poles. Rising temperatures are causing the ice caps to melt in both Arctic and Antarctic regions. The Arctic has lost a third of its ice since the 1970s and 2007 was the worst year on record for ice cap loss. Some scientists are predicting further acceleration in melting, and have even suggested that there may be ice-free summers in the Arctic as soon as 2030.

As a result of the melting of polar ice caps, sea level is rising globally, creating a flood risk for coastal areas and many world cities, such as New York and London, both of which are located on the flood plain. According to an Australian study, sea levels have risen by almost two centimetres every year since 1870, in line with temperature rises over the same period.

How does ice tell us the secret of why it is melting?

It is the ice itself that has helped us to solve the mystery of why the ice is melting. Trapped air that is found in very old ice is analysed by scientists to determine how carbon dioxide levels have changed over time. Ice cores are cross-sections drilled through the snow and ice. They allow us to look back in time. Over the past few decades, several long cores of ice between three kilometres and four kilometres long have been pulled up from the Greenland and Antarctic ice sheets to investigate long-term climatic change. Parts of the Antarctic ice are an amazing 500,000 years old. The ice was taken to a laboratory and melted, releasing bubbles of ancient air. Changes in air content - especially hydrogen - were then analysed, showing scientists how temperatures have warmed and cooled over time.

The pockets of air trapped within the ice enable scientists to reconstruct the gaseous composition of the atmosphere in the past, notably the concentrations of carbon dioxide (CO2). The ice can also be examined for concentrations of dust, volcanic ash and various chemicals - all giving evidence of what was in the atmosphere at various times in the distant past.

Starter

Who is the Iceman? Why was he murdered? Why was his body found 5,000 years later?

Have a look at the Iceman image. It shows the body of the Iceman. His body was found in an Austrian snowfield in 1991, having been frozen in ice for 5,000 years.

Who do you think the Iceman was?
How and why do you think he was murdered?
Why do you think his body came to be found so long after he was murdered?

Discuss your answers with the rest of the class.

Main Activity

Who killed the Iceman?

Read through the Iceman murder mystery document. It gives you some of the answers to the questions you discussed in the starter activity. Of course, some of the answers we just do not know.

Can you now solve the 5,000 glacier murder mystery of the Iceman?
Why was his body revealed so long after his death?

What is happening to the world's ice - why is it melting?

This is a good opportunity to recap the topic of global warming. If you do not need to, move straight on to the next task.

Now it is time for a bit of internet research. Using the Discovering Antarctica website, see if you can find the answers to the following questions:

• What is happening to the world's ice?

• Why is the ice melting?

• What is happening to Antarctica?

(Tip: look at the ‘A Changing Climate' section)
Your teacher might also show you a clip from the film ‘An Inconvenient Truth' so that you can draw a sketch map of the retreat of the Columbia glacier in Alaska.

How does ice tell us the secret of why it is melting?

For the final part of this activity, you will be taking a look at some of the techniques used by scientists to carry out geographical investigations into why the ice is melting.

Read the ice cores document which explains how ice cores are used to work out what the climate was like thousands of years ago.

Complete the activity on the sheet in which you are asked to plot a graph of how the carbon dioxide content of the atmosphere changed between 1800 and 2008.

• What pattern does your graph show?

• Why is this happening?

• How does the carbon dioxide level affect the temperature of the atmosphere?

• What does this mean for the future of the world's glaciers?

Plenary

Have a look at the help save the ice PowerPoint presentation. It will give you some ideas of the things you can do to reduce your carbon footprint and live more sustainably - and at the same time, do your bit to save the ice.

What other ideas do you have? Write your own checklist of small changes that you can make to your lifestyle that could have a positive effect on our glacial environments.