AP BIOLOGY

Detailed explanation-1: -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-2: -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-3: -"CO2 levels were extremely elevated during the age of the dinosaurs (which ended 65 million years ago), perhaps at some 2, 000 to 4, 000 ppm(Opens in a new tab). Tremendous CO2 emissions, from incessant and extreme volcanism, heated Earth and allowed dinosaurs to roam a sultry Antarctic(Opens in a new tab).

Detailed explanation-4: -First, the annual average CO2 concentration is increasing year-on-year. This is mainly due to the burning of fossil fuels, with further contributions from deforestation. Second, as human-driven emissions have increased, the rise in CO2 has accelerated. It took over 200 years to reach a 25% increase by 1986.

Detailed explanation-5: -Since the beginning of industrial times (in the 18th century), human activities have raised atmospheric CO2 by 50% – meaning the amount of CO2 is now 150% of its value in 1750. This is greater than what naturally happened at the end of the last ice age 20, 000 years ago.