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Weather and climate

Climate change

Emissions that increase greenhouse gasesEmissions that increase greenhouse gases Climates change over time. In the past, the Earth has been both hotter and cooler than it is now. During the Age of Dinosaurs 100 million years ago, there were no polar ice caps and tropical forests grew in temperate lands. More recently, 20,000 years ago, ice caps extended from the North Pole as far as northern Europe during the Ice Ages. Between about 1550 and 1800, in what were called the Little Ice Ages, winters were significantly colder than they are today. Most scientists are agreed that the global climate is now changing once more, this time due to the rapid growth of industry around the world.

Grinnell Glacier, USA, is retreating.Grinnell Glacier, USA, is retreating.

Global warming

The Earth is becoming warmer. The average temperature has risen by more than 0.5°C in the past century and is predicted to rise by 2°C by 2050—although this figure is far from certain. The effects may be felt by more frequent droughts, violent storms and changing climates. Glaciers are retreating (shrinking). The ice caps at both poles may start to melt, resulting in rising sea levels and the flooding of coastal regions where most cities are located.

Why is this happening? Most scientists are convinced that human activities—industries, power stations, cars and planes—has contributed to a huge increase in greenhouse gases in the atmosphere, causing global warming.

Carbon dioxide

Since the beginning of the Industrial Revolution in the mid-18th century, the burning of fossil fuels has contributed to the increase in carbon dioxide in the atmosphere from 280 ppm (parts per million, by volume of air) to over 400 ppm.

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