What are greenhouse gases?
Gases that trap solar heat in the earth’s atmosphere and contribute to global mean temperature are considered greenhouse gases. They take their name from the “greenhouse effect,” the term that compares the heat-trapping gases to the glass panes of a greenhouse for the way they warm the atmosphere. According to the National Energy Information Center, “Many gases exhibit these greenhouse properties. Some of them occur in nature (water vapor, carbon dioxide, methane, and nitrous oxide), while others are exclusively human-made (like gases used for aerosols).
Greenhouse gases occur naturally in the Earths atmosphere in addition to being emitted through human activities. This natural carbon cycle includes carbon dioxide used in plants during photosynthesis and the exchange of carbon dioxide between the atmosphere and the oceans. The primary natural processes that release CO2 into the atmosphere (sources) and that remove CO2 from the atmosphere (sinks) are: • Animal and plant respiration, by which oxygen and nutrients are converted into CO2 and energy, and plant photosynthesis by which CO2 is removed from the atmosphere and stored as carbon in plant biomass • Ocean-atmosphere exchange, in which the oceans absorb and release CO2 at the sea surface; • Volcanic eruptions, which release carbon from rocks deep in the Earths crust Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone.
A. www.ghgonline.org is an excellent website by local lad, Dave Reay, Senior Lecturer on the Carbon Management MSc at Edin Uni., It explains all about the greenhouses gases and not just CO2 as many people focus on Carbon Dioxide, and in actual fact we need to look at Methane (CH4) and more potent gases too, like CFC’s in fridges.
Greenhouse gases are gases in the atmosphere that have the capacity to absorb long-wave radiation emanating from the Earths surface. By absorbing this energy and re-radiating it, the gases cause the temperature of the Earths lower atmosphere and surface to increase. The most common greenhouse gases are water vapour and carbon dioxide. Back to TOP Are water vapour and carbon dioxide all we have to worry about? No. Other gases can absorb infrared radiation and contribute to greenhouse warming. These include methane, ozone, CFCs (chlorofluorocarbons) and nitrous oxide (released by fertilisers). Methane is the most important of these. Its atmospheric concentration has more than doubled since pre-industrial times. Methane sources include bacteria in paddy fields, cattle guts and natural gas from landfills and rotting vegetation. Molecule for molecule, other substances are even more potent greenhouse gases. A single molecule of either of the two most common CFCs has the same greenhouse warmi
Atmospheric trace gases that keep the Earth s surface warm are known as greenhouse gases. About three-quarters of the natural greenhouse effect is due to water vapour. The next most significant greenhouse gas is carbon dioxide. Methane, nitrous oxide, ozone in the lower atmosphere, and CFCs are also greenhouse gases.
