Although the causes of global warming are widespread, experts feel that the leading cause is that of overcrowding on the planet. Even though there are just over 5 billion human beings now, that number is expected to double in the next 60 years. More people means more energy, dri

Ground–level ozone accounts for 5%. (Stegar/Bowerman 1991) The most recent science assessment document for ground-level ozone (O3) was released in February of 1999. Ground-level ozone is a secondary pollutant, a highly reactive and unstable form of oxygen, and the most detrimental of "photochemical" pollutants. It is being continually created and destroyed in the troposphere by reactions involving oxygen molecules and ultraviolet light. The rate of synthesis of ozone is greatly increased by the presence of high concentrations of nitrous oxide and volatile organic compounds that react, with oxygen, in sunlight. (www.sierraclub.com/)

Nitrogen oxides account for 10%. (Stegar/Bowerman 1990) Nitrogen oxide emissions are a concern because they contribute to the formation of acid rain and, either directly or through the creation of ozone, lead to harmful effects on human health. According to estimates made by the U.S. Environmental Protection Agency (EPA), highway vehicles accounted for 35 percent of the 22 million tons of Nitrous oxide emissions in the United States in 1995, and electric utilities accounted for 29 percent. (www.ela.doe.gov)

Methane’s contribution is not far behind that of carbon dioxide. Methane accounts for about 20% of global warming. More than 425 million tons a year are generated by bacterial decomposition of organic matter – especially in landfills, flooded rice paddies, the intestines of cattle and termites, and by the burning of wood and fossil fuels. As the Earth’s population has grown steadily, so has the % of this gas, about 1% each year. However, methane emissions dropped 1.4% between 1997 and 1998, and are now nearly 5% lower than in 1990. EIA attributes the decline to increased capture of methane from landfills, mandated by EPA regulations but spurred on by operators trying to meet a deadline to receive tax credits for landfill gas recovery projects. (US Dept. of Energy’s Energy Information Assoc. (EIA))

Carbon dioxide

Some topics in this essay:
Statistics Carbon, Climate Weather, CARBON DIOXIDE, Agency EPA, Global Warming, Scientists Earth, Sciences Earth’s, NITROUS OXIDE, HFC’s PFC’s, , carbon dioxide, greenhouse gases, human activities, nitrous oxide, global warming, carbon dioxide methane, naturally occurring, dioxide methane, fossil fuels, solid waste, greenhouse gas, degree fahrenheit past, causes global warming, methane nitrous oxide, dioxide methane nitrous,