Greenhouse gases are the primary source of climate change. These gases include methane, carbon dioxide and the vapor from water. When they float into the atmosphere of Earth they can prevent heat from radiating out into space. This means that the heat is trapped and the temperature of the planet rises.
This is how global warming is created. This heat comes in the form of electromagnetic radiation. Usually this radiation would radiate away from the earth as long infrared wavelengths. However, if there are an abundance of greenhouse gases in the air then a portion of this infrared will be absorbed by them and into the atmosphere. This in turn heats up the atmosphere itself.
Greenhouse gases can be naturally occurring or they can be man made. Methane is a predominantly natural gas that is expelled by animals, particularly cattle. This makes the agricultural industry a significant contributor to greenhouse gases. Methane is also produced from burning coal.
Much of the water vapor in the atmosphere comes from the rivers and oceans of the world. This is created through the process of evaporation. However, this gas is also man made. The burning of hydrocarbon fuels is a contributing factor to the amount of this gas in the air.
By far the biggest cause of global warming is the gas carbon dioxide. This is expelled every day from living animals, including humans. Volcanoes and wild fires also throw this gas into the air. One of the most well publicised causes of carbon dioxide emission is the use of fossil fuels such as petroleum. This is done every day by millions of people and is a major issue. In order to prevent global warming from increasing, the amount of this fuel being burned needs to be drastically increased by a large amount of people.