AP BIOLOGY

Detailed explanation-1: -Fossil fuels – coal, oil and gas – are by far the largest contributor to global climate change, accounting for over 75 per cent of global greenhouse gas emissions and nearly 90 per cent of all carbon dioxide emissions. As greenhouse gas emissions blanket the Earth, they trap the sun’s heat.

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: -Key Takeaway: Carbon dioxide in the atmosphere warms the planet, causing climate change. Human activities have raised the atmosphere’s carbon dioxide content by 50% in less than 200 years.

Detailed explanation-4: -The concentration of CO2 has especially increased as a result of the Industrial Revolution and exponential growth in manufacturing activities around the world. Deforestation, agriculture, and fossil fuel use are the primary sources of CO2.

Detailed explanation-5: -In the United States, the largest source of greenhouse gases is transportation (29 percent), followed closely by electricity production (28 percent) and industrial activity (22 percent). Learn about the natural and human causes of climate change.