Page 40 - 新思维科学学生用书9 样章

1.4 Climate change

When rains fail, people may lose their harvests.

Long droughts also increase the risk of wildfires.
All of these changes affect not only people, but
also plants and animals.

This wildfire in Australia followed a long period
of drought.

Rising sea level

The increase in the Earth’s mean temperature
affects sea level. Water expands as it is heated,

so if the sea temperature increases, sea level rises. Melting ice caps and glaciers add extra water to the
oceans.

This glacier is getting smaller (retreating) as temperatures increase. The ice used to reach much higher
up the sides of the valley.

Sea level has been rising at a rate of about 3 mm per year. Scientists estimate that more than 600
million people are at risk from flooding caused by sea-level rise by the end of this century. Many
megacities are built on the coast – such as Shanghai, Mumbai and Los Angeles – and these are

especially vulnerable to sea-level rise.

Questions

5 Calculate by how much sea level is predicted to rise by the end of this century.
6 Explain why sea level is predicted to rise.

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