For the first time in 25 years, Americans are driving less. A study by Cambridge Energy Research Associates finds that the average American drove 13,657 miles in 2005, down from 13,711 in 2004, or 54 miles less per year average -- not much, but at least in the better direction. Last year also saw SUVs comprise a smaller chunk of new-vehicle sales; even though gas-guzzlers still account for more than half of such sales.
While consumption continues to rise, demand grew at a rate of only 0.3% last year and 1% for the first 11 months of 2006, compared to 1.6% per year from 1990 to 2004. High prices were a critical factor with gas sucking up about 3.8% of average U.S. household spending. The graying of the population has also contributed, as older drivers tend to drive less.
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However, in 2005, carbon emissions from the burning of fossil fuels climbed to a record high of 7.9 billion tons, an increase of some 3% from the previous year. Annual global emissions have been increasing since the beginning of the Industrial Revolution in the late eighteenth century, when humans first began burning fossil fuels on a large scale to produce energy. Since the early 1900s, emissions have been rising at an increasingly rapid pace. Annual emissions have grown by a factor of fifteen since 1900, advancing nearly 3% a year over that time.
Half of all energy-related carbon emissions come from only four countries. The United States, with less than 5% of the world’s population, accounts for 21% of carbon emissions. It is followed by China, which emits 18%. Both countries are heavy users of coal, the most carbon-intensive fossil fuel. Russia accounts for 6% of carbon emissions, just ahead of Japan, which produces 5% of the global total. Other major contributors to global carbon emissions are India, Germany, Canada, the United Kingdom, South Korea, and Italy. The United States, Australia, and Canada each emit roughly 5 tons of carbon per person each year. This is five times the figure in China and 17 times that in India.
Some 40% of energy-related emissions come from the burning of fossil fuels, such as oil, coal, and natural gas, to generate electrical power. The transportation sector is the second-largest source worldwide, responsible for 20% of all carbon emitted. Residential and commercial buildings account for roughly 15% of the total, and the industrial sector, another 15%. The remaining 10% of energy-related emissions come from a variety of minor uses, including fuels burned by sea-going ships.
As global emissions of carbon increase, they raise the levels of carbon dioxide (CO2) in the atmosphere. The average atmospheric concentration of CO2 reached 380 parts per million by volume in 2005, up 2.2 parts per million from 2004 levels and up 103 parts per million from pre-industrial times. The Intergovernmental Panel on Climate Change (IPCC), a global body of some 2,000 scientists, estimates that the current atmospheric CO2 concentration has not been exceeded over the last 420,000 years and probably not during the past 20 million years.
Experts predict that the effects of global warming will be far more dramatic if carbon emissions force atmospheric CO2 levels above 550 parts per million. Beyond this threshold, widespread flooding, droughts, and storms will be more severe. If carbon emissions continue to increase as projected, this level is likely to be reached in the second half of this century. To prevent this from happening, scientists estimate that carbon emissions must be cut by some 70%.
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Labels: energy, transportation