Greenhouse gas in the atmosphere (water vapor, carbon dioxide, methane, nitrous oxide and chlorofluorocarbons) keep some of the heat from escaping.
Human activities, like the burning of fossil fuels, have increased the amount of CO2 in the atmosphere by more than a third since the Industrial Revolution.
Effects
oceans
Ice sheets are melting.
Sea levels riss.
Coastal areas were flooded.
weather
more extreme
more intense major storms, floods and heavy snowfall, but also longer and more frequent droughts.
food sources
Growing crops becomes more difficult.
The areas where plants and animals can live shift and water supplies are diminished.
health
increase the amount of smog
Exposure to higher levels of smog can cause health problems.