AP BIOLOGY

Detailed explanation-1: -When fossil fuels are burned, they release large amounts of carbon dioxide, a greenhouse gas, into the air. Greenhouse gases trap heat in our atmosphere, causing global warming. Already the average global temperature has increased by 1C.

Detailed explanation-2: -Human Activity Is the Cause of Increased Greenhouse Gas Concentrations. Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This increase happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2.

Detailed explanation-3: -Carbon dioxide from the burning of fossil fuels is the largest single source of greenhouse gas emissions from human activities.

Detailed explanation-4: -Burning fossil fuels, changing land use, and using limestone to make concrete all transfer significant quantities of carbon into the atmosphere. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising; it is already greater than at any time in the last 3.6 million years.

Detailed explanation-5: -The main human activity that emits CO2 is the combustion of fossil fuels (coal, natural gas, and oil) for energy and transportation.