What is global warming?
Renewable energy is also known as "clean energy" or "green power" because it doesn’t pollute the air or the water. Fossil fuels like oil, gas and coal are very harmful to the environment, and when burnt, like in the engines of cars and in the ovens of factories, gases are emitted. The best known gas is Carbon Dioxide or CO2 which is a major cause of global warming and climate change.
Global warming is the increase in the Earth’s temperature. There have always been fluctuations in the temperature of the Earth, however the rise in temperature is occurring with greater speed than ever before, and most scientists agree that this is largely due to the activities of humans.
The CO2 released into the air causes our atmosphere to work like a greenhouse: the heat of the sun can come in, but cannot leave. Just like in a garden greenhouse sunshine comes through the glass heating the greenhouse and everything inside it. Plants (like tomatoes) are kept in a green house because they need warm temperatures to grow in. Of course, there are also plants which prefer cooler temperatures, and would die in the warm greenhouse conditions.
As more CO2 is released into the atmosphere our planet is heating up as if it were in a greenhouse. This is a real problem, because not all parts of the world can survive with warmer climates. The ice caps at the north and south poles are melting, which is leading to a rise in sea levels which in turn will change rainfall patterns. There will be many, many changes which will have a huge impact on plants, wildlife and humans. We have already begun to see the effects of climate change as flooding increases.