GEOLOGY

Detailed explanation-1: -Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years. The largest source of greenhouse gas emissions from human activities in the United States is from burning fossil fuels for electricity, heat, and transportation.

Detailed explanation-2: -In the United States, most of the emissions of human-caused (anthropogenic) greenhouse gases (GHG) come primarily from burning fossil fuels-coal, natural gas, and petroleum-for energy use.

Detailed explanation-3: -Annual greenhouse gas emissions by sector Here we see that electricity and heat production are the largest contributor to global emissions. This is followed by transport, manufacturing and construction (largely cement and similar materials), and agriculture.

Detailed explanation-4: -Although all of the activities on the list cause greenhouse gas emissions, transportation and electricity generation are the biggest causes.

Detailed explanation-5: -Electricity generation (40%) and transportation are the two largest sources of greenhouse gas emissions in the US. 69% of the electricity in the US is generated by fossil fuels. 50% of it is from coal. One way to lessen the amount of fossil fuels used is by encouraging conservation.