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The greenhouse effect is a natural phenomenon that is essential to keeping the Earth’s surface warm. Like a greenhouse window, greenhouse gases allow sunlight to enter and then prevent heat from leaving the atmosphere. These gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor. Human activities — especially burning fossil fuels — are increasing the concentrations of many of these gases, amplifying the natural greenhouse effect. Image courtesy of the Marian Koshland Science Museum of the National Academy of Sciences
Source: Marian Koshland Science Museum of the National Academy of Sciences.