Key Stage 3 (KS3) Energy Practice Test 2025 - Free KS3 Energy Practice Questions and Study Guide

When fossil fuels such as coal, oil, and natural gas are burned for energy, one of the key greenhouse gases released into the atmosphere is carbon dioxide. This occurs because the combustion process chemically converts the carbon present in fossil fuels into carbon dioxide, which is then emitted as a byproduct.

Carbon dioxide is a significant greenhouse gas because it contributes to the greenhouse effect, which traps heat in the Earth’s atmosphere, leading to global warming and climate change. The increase in carbon dioxide levels from human activities, particularly from the burning of fossil fuels, has been a major concern for environmental scientists and policy makers.

Other gases mentioned, such as methane and nitrous oxide, are also greenhouse gases, but they are not the primary products of fossil fuel combustion. Methane is typically released during the extraction and transportation of fossil fuels rather than during their burning, while nitrous oxide is mainly produced from agricultural and industrial activities. Ozone, although a greenhouse gas, is formed through reactions involving sunlight and other pollutants, rather than being directly emitted by fossil fuel combustion.