Global warming is that concept that due to the dramatic increase of CO2 emissions produced by the use of energy sources such as coal. This is believed to have caused a greenhouse effect. The logic being, that in normal circumstances the sun's rays would bounce off of the earth's surface and out of atmosphere. However, because CO2 is beginning to fill the atmosphere, it makes it more difficult to for the sunlight to leave, gradually heating up the earth.
Detriments to the Economy. Edit
Global warming is believed to be responsible for for stronger and stronger storms. Since global warming is causing warmer waters, and since warmer waters cause longer and stronger hurricanes, it does more damage. The previous 2 hurricanes, including Maria, caused billions in damages for the state and for the people. It is also believed that many coastal cities would start to flood with the rise of sea-level, sinking parts of cities like Miami, New York, and Los Angeles.
It also causes more severe droughts in many places, such as California or Arizona. This could devastate the local agriculture.