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), in particular, 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.
The inequality in the use of resources between MEDCs and LEDCs is shown by measuring and comparing their carbon emissions per capita. Countries that use a lot of fossil fuels to produce energy to power industry, produce electricity and heat homes, also produce a lot of carbon gasses.
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.
The diagram below shows the countries that contribute the biggest percentage of the world's carbon emissions.