It's all about energy!
Greenhouse gases like carbon dioxide, methane and water vapor in the air trap energy from the sun. Without this layer, Earth would be a frozen, lifeless rock in space. The atmosphere and the life on the planet are dependent upon each other. Without one, there wouldn't be the other. As life changed on the planet, the atmosphere changed with it. Too many greenhouse gases, and Earth becomes like Venus: an overheated, hostile lifeless planet with an atmospheric pressure so powerful it can implode a spaceship within an hour
They call this the greenhouse effect because the earth's atmosphere traps the sun's energy just like the covering of a greenhouse traps the sun's energy. You experience this every sunny day in a car with its windows closed. Except in the case of your car, almost all of that trapped energy is expressed as heat. It works a little differently on a planet with an atmosphere. Heat energy in the atmosphere is also converted into other forms of energy. Examples include: blowing wind, evaporation, ocean waves, ocean currents, atmospheric currents like the Jet Stream, electrical storms, thunder. Much of heat energy is absorbed by oceans (which warm) and ice caps (which melt). Extra trapped heat creates warmer oceans, stronger ocean currents, stronger hurricanes, more frequent hurricanes, stronger winds, greater evaporation, more and longer droughts, and stronger wind currents. It can push cold air down far from the north and warm air far up from the south which can lead to unusual weather patterns.
Carbon dioxide is pulled from the atmosphere by coral reefs, and by trees, bushes, grasslands and wetlands as they grow and reproduce. By protecting and improving these habitats, and by eliminating excessive greenhouse gas emissions by humans, scientists believe the planet's atmosphere can stabilize and continue to protect and contribute to the delicate balance of life on earth.
Economists believe the benefits of moving away from fossil energy and toward renewable energy will greatly outweigh the cost of staying with fossil fuels.