The cycling of carbon dioxide in photosynthesis and cellular respiration are main components of the carbon cycle. Carbon is also returned to the atmosphere by the burning of organic matter (combustion) and fossil fuels and decomposition of organic matter.

Eighty-five percent of all human-produced carbon dioxide emissions come from the burning of fossil fuels like coal, natural gas and oil, including gasoline. The remainder results from the clearing of forests and other land use, as well as some industrial processes such as cement manufacturing.

Carbon dioxide is added to the atmosphere naturally when organisms respire or decompose (decay), carbonate rocks are weathered, forest fires occur, and volcanoes erupt. Carbon dioxide is also added to the atmosphere through human activities, such as the burning of fossil fuels and forests and the production of cement.

Carbon dioxide is used as a refrigerant, in fire extinguishers, for inflating life rafts and life jackets, blasting coal, foaming rubber and plastics, promoting the growth of plants in greenhouses, immobilizing animals before slaughter, and in carbonated beverages.

The three ways by which CO2 is returned back into atmosphere are: (i) By the decomposition of dead organic matter. (ii) As the product of respiration by both plants and animals. (iii) As the gaseous waste formed by the combustion of fuels like coal, wood, petrol and gaseous fuels.

When animals eat food, they get carbon in the form of carbohydrates and proteins. The carbon combines with oxygen to form carbon dioxide (CO2) and is released back into the atmosphere as a waste product when animals breathe and exhale.

Photosynthesis removes CO2 from the atmosphere and replaces it with O2. Respiration takes O2 from the atmosphere and replaces it with CO2.

Carbon dioxide causes about 20 percent of Earth’s greenhouse effect; water vapor accounts for about 50 percent; and clouds account for 25 percent. Likewise, when carbon dioxide concentrations rise, air temperatures go up, and more water vapor evaporates into the atmosphere—which then amplifies greenhouse heating.

300 to 1,000 years

CO2 makes up only about 0.04% of the atmosphere, and water vapor can vary from 0 to 4%. But while water vapor is the dominant greenhouse gas in our atmosphere, it has “windows” that allow some of the infrared energy to escape without being absorbed.

Greenhouse Gas Removal (GGR) refers to an technique that removes greenhouse gases from the atmosphere through mechanical means. A more common umbrella term is Carbon Dioxide Removal (CDR), which excludes methods that remove other greenhouse gases such as methane.

Burning fossil fuels and wood is one source of the increase in atmospheric nitrous oxide, however the main contributor is believed to be the widespread use of nitrogen-base fertilisers. Sewage treatment plants may also be a major source of this gas.

China

Nitrous oxide measurements were made on nine vehicles. Based on this value and the rate of N2O increase in the stratosphere, vehicles in the United States emit about two percent of anthropogenic N2O emissions and contribute only 0.1 percent of the calculated temperature increase from greenhouse gases.

In the first two decades after its release, methane is 84 times more potent than carbon dioxide. While methane doesn’t linger as long in the atmosphere as carbon dioxide, it is initially far more devastating to the climate because of how effectively it absorbs heat.

Since cows are the most carbon-intensive part of the food industry — cattle are responsible for 62 percent of agricultural emissions — eating fewer of them is one of the most powerful steps an individual can take toward protecting the planet.