Causes

One of the main greenhouse gases is carbon dioxide (CO2).

As trees grow they take in CO2 from the air. When the wood dies the CO2 is returned to the air. Forest clearance and wood burning (such as happens in tropical rain forests) is increasing the latter half of the process, adding to the CO2 in the atmosphere. Deforestation is now out of control. For example in 1987 an area of the Amazon rain forest the size of Britain was burned, adding 500 million tonnes of CO2 to the atmosphere. According to 2018 satellite data compiled by a deforestation monitoring program called Prodes, deforestation has hit its highest rate in a decade. About 7,900 km2 (3,050 sq miles) of the rainforest was destroyed between August 2017 and July 2018. The loss of the forests also means that there are fewer trees to absorb CO2.

However, as large a contribution as deforestation makes, studies in 2018 - 2019 suggest deforestation only causes around 8 to 10% of global CO2 emissions, the rest comes from the burning of coal, oil and other fossil fuels. These fossil fuels are burned in cars, power stations and factories of the wealthier nations such as the USA, Western Europe and the USSR.  The concentration of CO2 has increased 40% since the industrial revolution, half of this rise has been in the last 30 years. It is expected to double within decades. 

Televisions, lights and computers use electricity that is created mainly from burning oil and coal. This is why saving energy by doing simple things like turning off the lights helps to reduce pollution. Cars are also major sources of CO2.

It is also accepted that those of us living in the Western world, or more developed countries contribute far more to this problem than those in developing countries.  The average European is responsible for nearly 2.5 times as much atmospheric carbon as a Latin American.

For more information see Pollution factsheets and to find out more about fossil fuels take a look at Energy.  Related factsheets include Acid Rain, Meat free Mondays, Our Battered Biosphere.