Climate scientists have concluded that the earth is warming primarily as a result of human activity, and that, consequently, the most colossal environmental disturbance in modern history is underway. Since the Industrial Revolution, ever increasing concentrations of carbon dioxide, methane, nitrous oxide, and other potent greenhouse gases are being emitted into the atmosphere by deforestation and the burning of fossil fuels. These gases are slowly but surely altering cycles of matter and life, and interfering with the earth's natural cooling processes. Melting sea ice, permafrost.
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