You don't need me to explain science to you line-by-line, you can read for yourself: https://climate.nasa.gov/causes/ > Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as "forcing" climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as "feedbacks." CO2 promotes plant growth, but the climate disruption associated with global warming is likely to have a larger, negative effect on world food supplies and especially forests.