Global Environment Change
Most climate scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect"1 — warming those results when the atmosphere traps heat radiating from Earth toward space. Human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). Global warming is primarily a problem of too much carbon dioxide (CO2) in the atmosphere—which acts as a blanket, trapping heat and warming the planet.