Where do greenhouse gases come from?
Most of the carbon dioxide in our atmosphere comes from plants and the decomposition of organic matter. These release more than 10 times the carbon dioxide as that released by human activities. But these releases have generally been in balance during the centuries leading up to the industrial revolution, with carbon dioxide absorbed by earth’s vegetation and the oceans. Gas emissions have taken on a new pattern since the beginning of the industrial revolution, when atmospheric concentrations of carbon dioxide increased nearly 30 percent, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15 percent. These increases have enhanced the heat-trapping capability of the earth’s atmosphere. The Source of Additional Greenhouse Gases Scientists generally believe that the combustion of fossil fuels and other human activities are the primary reason for the increased concentration of carbon dioxide.
Greenhouse gases are emitted from a variety of natural and anthropogenic (human) sources. Carbon dioxide has the greatest effect on climate change because of its abundance. CO2 is emitted from the burning of fossil fuels (coal, oil, and natural gas), solid waste incineration, and wood burning (deforestation). Only a small proportion of CO2 emissions come from natural sources, such as plant decay, volcanic eruptions, and animal respiration (BBC 2004). CO2 emissions from oil and natural gas account for 82% of the anthropogenic GHG emissions in the United States (EIA 2001). Methane has the second most significant effect on climate change. It is 21 times better than CO2 at trapping heat near the earths atmosphere (methanes GWP is 21), but it is not emitted in as high a volume. Human-related activities account for approximately 70% of global methane emissions (Fung et al. 1991; IPCC 1992), while natural sources account for the other 30%. The major anthropogenic sources of methane in the US
Greenhouse gas emissions resulting from human activities are substantially increasing the atmospheric levels of the greenhouse gases which include carbon dioxide, methane, halocarbons (HFCs), and nitrous oxide. Carbon dioxide emissions have increased 30% during the past century largely due to fossil fuel combustion which produces the largest amount of CO2 emissions (about 80% of United States GHG emissions and about 87% of California emissions). In California, approximately 43% of the CO2 emissions come from cars and trucks. Methane emissions have doubled in the past 100 years. Over the same period, nitrous oxide levels have risen about 15%. Agriculture is a major source of both methane and nitrous oxide, with additional methane coming primarily from landfills. Halocarbons are another greenhouse gas. Most halocarbon emissions come from their use as refrigerants, solvents, propellant agent, and industrial processes. Manufactured compounds, like HFCs, persist in the atmosphere for long p
Most of the increase in carbon dioxide comes from burning of fossil fuels such as oil, coal and natural gas for energy, and from deforestation. Cows, sheep and other ruminant animals burp methane into the air. Rice paddies also generate methane. Other sources of methane are landfills, burning vegetation, coal mines and natural gas fields. Nitrous oxide concentrations are increasing because of changes to the way in which we use land, from fertiliser use, from some industrial processes, and from burning vegetation. Ozone is a component of photochemical smog, which, in turn, is the result of emissions of hydrocarbons and nitrogen oxides from motor vehicles and industry. CFCs were made in the past for refrigerants, spray pack propellants, producing foam plastics and as solvents for electronic components. All developed countries, including Australia, have stopped producing CFCs.
Most of the emission of greenhouse gases comes from the burning of fossil fuels including coal and petroleum which are used to create energy for much of the world today. Considering the heating, cooling, and other power needs we have to live a “comfortable” life today, humankind is primarily responsible for the influx of the greenhouse gases in the atmosphere which contributes to an accelerated green house effect, thus driving the temperature of the earth upward, and creating issues with weather, along with the lives of plant and animal species. The energy related explosion of carbon dioxide is the biggest contributor to the greenhouse effect, with an astonishing 82% of the total man-made gas emissions during 2006, as according to the Energy Information Administration and a brochure released in May 2008.
