How do greenhouse gases cause the greenhouse effect?
Greenhouse gases cause the greenhouse effect by trapping heat.
Greenhouse gases work the same as the windows of a greenhouse. They allow sunlight in but prevent the heat generated by that sunlight from escaping.
The atmosphere naturally lets some sunlight through and reflects some sunlight. (If we didn't have an atmosphere, our planet would be much, much cooler.)
As water vapor, CO2, and other greenhouse gases (GHGs) increase, they trap more and more sunlight or energy. Energy that would normally escape from earth cannot, and the planet warms.
To learn in detail how greenhouse gases trap heat, see this question.
NASA also has a webpage designed specifically for kids that can be found here.
The same way a greenhouse works. Sunlight comes in through the windows but the heat generated by that sunlight is blocked by those windows. In this cause the windows are greenhouse gases.
The answer to this question is basically the same as the answer to other similar questions, so I will post a link to how the process works.