In recent years scientists have noticed that the rate of climate change has been increasing. A number of theories exist as to how this has happened but all scientists agree that the impact of these changes could be far-reaching if we do not learn to manage our resources effectively.
When fossil fuels burn, they produce greenhouse gases that are having a global impact on temperature and weather systems.
Fossil fuels and greenhouse gases
When fossil fuels are burned by industry, in power stations and by vehicles and planes, gases (as unwanted by-products known as carbon emissions) enter the atmosphere.
Carbon dioxide (CO2) is given off when fossil fuels, such as oil and coal, are burned.
Although these gases have always been present in the world's atmosphere, their concentration is gradually increasing as more and more fossil fuels are burned.
Scientists believe that the build-up of so-called greenhouse gases in the atmosphere acts like a blanket or greenhouse around the planet; heat is trapped inside the Earth's atmosphere.
This is the greenhouse effect, and the resulting increase in global temperatures is called global warming.
Plants and trees need CO2 and use it up. However, if there is too much CO2 in the atmosphere - due to factories and power stations, combined with a reduction in the number of trees, through deforestation - CO2 builds up in the atmosphere.
The build-up of CO2 is believed to contribute to global warming through the greenhouse effect. This is why CO2 is called a greenhouse gas.
The biggest producers of CO2 in the world are the United States (USA), China, Russia, Japan, India, Germany, United Kingdom, Canada, Italy and Mexico.
The largest producers by far are the USA and China.
The diagram below shows the countries that contribute the biggest percentage of the world's carbon emissions.