The Earth has always got hotter and cooler, wetter and drier, over long periods of time. These changes are part of natural cycles, but many scientists agree that changes are also affected by what people do. Some scientists are still debating how much this is the case.
Scientific evidence suggests that the Earth has become hotter in the last 100 years. Some consequences of this are sea levels rising, ice sheets melting, deserts spreading.
Gases in the Earth’s atmosphere trap heat and reflect it back to the surface. This helps stop us from freezing. Too much, however, may cause overheating. Some of these gases [like methane and carbon dioxide] are released through what people do eg burning fossil fuels such as oil and coal.
There is sometimes some confusion about the difference between carbon and carbon dioxide. Carbon is the element that combines with oxygen to produce carbon dioxide. For every one molecule of carbon, there are two molecules of oxygen (CO2). Carbon on its own is not a greenhouse gas, but carbon dioxide is often shortened to carbon for ease of reference.
Burning fossil fuels such as gas, coal or oil, releases carbon dioxide into the atmosphere [carbon emissions]. Carbon dioxide is naturally re-absorbed by plants and trees. However, we are burning fuels where the carbon dioxide has been trapped under the earth's surface for millions of years, and we're doing it so quickly that plants and trees that are alive now are struggling to take it all in.
As well as carbon dioxide, there are other gases (such as methane) which cause global warming. Collectively, they are known as 'greenhouse gases'.
All plants absorb carbon dioxide, and give out oxygen into the atmosphere. Large forests and ocean plant life are important for keeping the planet healthy. Carbon is an essential part of all living things