Global warming is an environmental issue ongoing in the past years. It is about the planet Earth heating up. One major cause of the warming is the greenhouse effect. Certain gases, such as CO2, keep the heat within the Earth atmosphere. These gases get into the air by burning fossil fuels such as coal, oil or natural gas. Fossil fuels contain a lot of carbon, which is when burnt, combines with oxygen to form carbon dioxide.
One of the main solutions to avoid global warming is to replace fossil fuel energy sources with renewables, such as wind, solar, hydropower etc. Another carbon free energy source is nuclear energy, which has a different set of challenges to solve.
To learn more about this visit this article by the National Geographic.