What causes climate change?

The atmosphere is like a blanket that keeps us warm. It contains greenhouse gases that stop the sun’s rays escaping back into space. But what would happen if we increased the number of greenhouse gases in the atmosphere? We’d get too hot. That’s what’s happening right now.

Humans burn fossil fuel to power lights and factories, to run our cars, ships and motorbikes. We also burn vegetation when we clear land for farming. This produces the most important greenhouse gas of all, carbon dioxide, known as CO2.

There are other greenhouse gases too, like methane which farm animals burp or which leaks from gas pipelines, and nitrous oxide which comes from the fertilizers used in agriculture. But CO2 from oil, coal, and gas is the biggest problem, and we use it as a benchmark to measure the other gases.

CO2 makes up the bodies of all living things including you, and is ‘fixed’ (trapped) when plants and algae photosynthesize. Most carbon used to leave the atmosphere naturally thanks to plants, algae, and the ocean absorbing it. Coal, for example, is made of ancient trees, and oil is made of ancient algae.

But since the Industrial Revolution in the 19th century, we’ve burned more and more fossil fuels, and cleared more and more land. To stay safe, we need to get global levels of CO2 back down to 350 parts per million in the atmosphere (currently 410ppm) and stop warming beyond 1.5 degrees Celsius (currently about 1 degree).