Greenhouse gasses (also known as GHGs) are gasses in the earth’s atmosphere that trap heat. They absorb solar energy and keep heat close to Earth's surface, rather than letting it escape into space. These gasses act like the glass walls of a greenhouse – hence the name, greenhouse gasses. Not only does the concentration of greenhouse gasses influence Earth’s temperature but temperature fluctuations caused by natural climate factors in turn alter these concentrations. Scientists agree greenhouse gasses are the cause of global warming and climate change.
Major greenhouse gasses and sources
Carbon dioxide (CO2): Carbon dioxide is the primary greenhouse gas, responsible for about three-quarters of emissions. CO2 is released through natural processes, such as volcanic eruptions, plant respiration and animals and humans breathing. The atmospheric CO2 concentration has increased by 47% since the Industrial Revolution began in the 1800s, due to human activities like the burning of fossil fuels and large-scale deforestation. Due to its abundance, CO2 is the main contributor to climate change.
Methane(CH4): The main component of natural gas, methane is released from cattle farming, landfill waste dumps, rice farming and the traditional production of oil and gas. A molecule of methane doesn't stay in the atmosphere as long as a molecule of carbon dioxide (about 12 years) but it is at least 84 times more potent over two decades. It accounts for about 16% of all greenhouse gas emissions.
Nitrous oxide (N2O): Nitrous oxide occupies a relatively small share of global greenhouse gas emissions (about six percent), but it is 264 times more powerful than carbon dioxide over 20 years, and its lifetime in the atmosphere exceeds a century, according to the Intergovernmental Panel on Climate Change (IPCC). N2O is produced through the large-scale use of commercial and organic fertilizers, fossil-fuel combustion, nitric-acid production and biomass burning.
Industrial greenhouse gasses: In addition to naturally occurring greenhouse gasses, there are three industrial fluorinated gasses that are solely man-made (during industrial processes) and do not occur in nature. These are- hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulphur hexafluoride (SF6). Although these gasses are present in very small concentrations in the atmosphere, they are highly potent due to their ability to trap heat very effectively. SF6, for instance, is used in high-voltage electricity equipment, and has a ‘Global Warming Potential’ 23,000 times greater than CO2.
Other greenhouse gasses include water vapor and ozone (O3). Water vapor is actually the world's most abundant greenhouse gas, but it is not tracked the same way as other greenhouse gasses because it is not directly emitted by human activity and its effects are not well understood. Similarly, ground-level or tropospheric ozone (not to be confused with the protective stratospheric ozone layer higher up) is not emitted directly but emerges from complex reactions among pollutants in the air.
Virtually every sector of the global economy, from manufacturing to agriculture to transportation to power production, contributes greenhouse gasses to the atmosphere, so all of them must evolve away from fossil fuels if we are to avoid the worst effects of climate change.
On an individual level, switching to sustainable practices like reusing and recycling, and switching to electric vehicles can make a huge contribution in saving the planet.