With Congress deep in debate over legislation aimed at the prevention of global warming, and skeptics ramping up their rhetoric, it seemed like a good time to take a step back to some basics — more accurate information is critical here. Step one in figuring in out how we can help in the battle against climate change involves answering questions like “What are the major causes of global warming?”
What causes global warming?
[social_buttons]Scientists have understood the greenhouse effect since the early 19th century; the first paper on the topic was published in 1896. Essentially, certain gases trap energy from the sun: according to the Intergovernmental Panel on Climate Change’s Fourth Assessment Report, greenhouse gases “act as a partial blanket for the longwave radiation coming from the surface. This blanketing is known as the natural greenhouse effect.”
What are greenhouse gases?
Several compounds contribute to the greenhouse effect, including
Carbon dioxide (CO2): Carbon dioxide is probably the best-known greenhouse gas. According the US Environmental Protection Agency, “Carbon dioxide enters the atmosphere through the burning of fossil fuels (oil, natural gas, and coal), solid waste, trees and wood products, and also as a result of other chemical reactions (e.g., manufacture of cement)”
Methane (CH4): Methane is produced by the production and transportation of a number of fossil fuels, by livestock, and by the decay of organic materials. It is 20 times more potent a greenhouse gas than CO2.
Water vapor: Water vapor is the most abundant greenhouse gas, and skeptics have tried to use this fact to dismiss claims about atmospheric CO2 levels. The Christian Science Monitor noted earlier this year, though, that “As CO2 concentrations have risen and warmed the atmosphere, the warming has allowed the atmosphere to hold more water vapor, which in turn further warms the atmosphere.” RealClimate noted this fact several years ago, claiming that water vapor is a feedback, not a forcing.
Nitrous oxide (N2O): Nitrous oxide is produced largely by agricultural practices, as well as manure and sewage management.
Fluorinated gases (or High Global Warming Potential gases): This group of gases, which includes hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, are “synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes.” Ironically, several of these compounds are used widely as substitutes for ozone-depleting substances.
What are the major sources of greenhouse gases?
While all greenhouse gases (except fluorinated gases) occur in nature, the EPA’s most recent Inventory of Greenhouse Gas Emissions and Sinks shows a 20% rise in emissions of CO2 from human sources over the study period of 1990-2004; methane and nitrous oxide emissions, fortunately, have decreased over this period. Among the most prominent sources of greenhouse gases:
- Fossil fuel combustion
- Cement production
- Incineration of wastes
- Agricultural soil management
If were going to prevent further global warming, understanding its sources, and our contributions to it, are critical. We can reduce our emissions of greenhouse gases while maintaining economic sustainability… let’s hope our leaders keep that in mind as they debate the path forward in addressing climate change.