The greenhouse effect involves the absorption and re-emission of infrared radiation by certain gases in the atmosphere. Here is a way to fill in the blanks in your statement:
"And the greenhouse effect far infrared radiation is released from the Earth's surface and absorbed by greenhouse gases in the atmosphere. These gases have increased in concentration over the past century."
This highlights the process by which the Earth's surface emits infrared radiation, which is then absorbed and re-emitted by greenhouse gases, contributing to the warming of the atmosphere. Furthermore, it notes the significant increase in the concentration of these gases due to human activities, such as burning fossil fuels and deforestation.