Greenhouse gases, such as carbon dioxide (CO₂), methane, nitrous oxide and fluorinated gases are emitted into the atmosphere through varying methods, and trap heat in our atmosphere Overview of Greenhouse Gases | US EPA. 

Carbon dioxide is emitted through the burning of fossil fuels such as coal, oil and natural gas. It can also occur through certain chemical reactions such as cement production and comprises most greenhouse gases (2022 it was 80% of greenhouse gases in the United States (US)). The source of CO₂ is mainly human related, and this has increased since the industrial revolution Carbon Dioxide Emissions | US EPA. The two top producers of CO₂ are electricity (coal, natural gas and oil) and energy for transportation (gasoline and diesel); these comprise 65% of total CO₂ and 52% of total greenhouse gases in the US. 

The three top emitters of methane are agriculture, energy/industry and the third is waste from businesses and homes in the form of landfills. In agriculture methane is emitted from domestic animals such as cattle, sheep and goats as part of their normal digestion. Additional methane is released when their manure is stored in holding tanks or lagoons Methane Emissions | US EPA. Natural gas and petroleum systems emit methane during the processing, storage and transportation for energy and industry production. Our landfills emit methane during decomposition and is the 3^rd highest amount in the US. 

Sources of nitric oxide are mainly from agriculture, wastewater management, industry and fuel combustion, representing only 6% of CO₂ emissions. Fluorinated gas emissions are low and mainly come from industrial processes and semiconductor manufacturing Fluorinated Gas Emissions | US EPA.

Greenhouse gases absorb heat energy from the earth’s surface, and it can remain in the atmosphere for years to even centuries What Are Greenhouse Gases and Why Do They Matter | NOAA Climate.gov. Some of the heat energy can be reflected back to the earth and trapped near the surface increasing its’ temperature.