Q:Answer the question based on the following text.  Question:   Billionaire Joey McMoneystuffs added 3 new jets to his already large fleet of personal aircraft. One day, he decided to have them race each other, burning excess fuel and adding greenhouse gases to the atmosphere. When the resulting ultraviolet radiation becomes trapped, the Earth's heat index will increase or decrease?    Text:  If there are more greenhouse gases in the atmosphere, more ultraviolet radiation will be trapped and the Earth will heat up.
A:
increase