There is increasing scientific evidence that carbon dioxide and other greenhouse gases released into the atmosphere are exerting a profound effect on the Earth’s climate: increasing extreme weather events, changing rainfall and crop productivity patterns, and fueling the migration of infectious diseases.
Climate Change Factsheet (178 KB)
Causes & Consequences
Human activity has influenced global climate systems by greatly increasing atmospheric concentrations of greenhouse gases, primarily carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and tropospheric ozone (O3).
Why Should a Few Degrees of Warming Be a Cause For Concern?
The International Panel on Climate Change (IPCC) reports that 23 global climate models predict world temperatures will rise by 2 to 12 degrees Fahrenheit by the end of the century. Climate modelers conclude there is a 66 percent chance that the increase by 2100 will be between 3.6 and 8.1 degrees.
Read the IPCC 2007 Climate Change summary for policy makers.
These changes may lead to a number of potentially serious consequences. For example, mid-and high-latitude regions including much of the United States, Europe and Asia, could experience an increase in the incidence of heat waves, floods and droughts as the global climate changes. The impacts of such extreme events on human welfare as well as natural ecosystems could be significant.
For Colorado, global warming will likely mean diminished snow pack, increased drought, more insect outbreaks in forests, an earlier and longer wildfire season, reduced habitat for native species, and less economic growth in certain industries, such as farming and skiing. The IPCC reports that the Rocky Mountains will probably see less snow and a shorter snow season as the century wears on. Although global-warming-caused increases in water vapor could result in increased precipitation, higher temperatures will probably create a drier climate overall. Local temperatures may average 7 degrees warmer than current temperatures, according to Linda Mearns, a National Center for Atmospheric Research senior scientist.
Criticism of Climate Change
Many skeptics of climate change claim climate change is a result of a natural cycling of the sun that flexes over thousands of years. However, the 2007 IPCC climate change summary includes proven data that the solar factor is one half of what was originally assumed. The report states, "It is very unlikely that climate changes of at least the seven centuries prior to 1950 were due to variability generated within the climate system alone."
Local Governments Think Globally, Act Locally
Boulder County and other local governments are not waiting for Federal action to reduce harmful emissions. The City of Boulder's Office of Environmental Affairs has created a Climate Action Plan, and in November 2006, Boulder residents approved a Climate Action Plan tax - the first in the country - to fund the necessary programs and changes to implement the Plan.
In 2005, the Boulder County Commissioners adopted two Sustainability resolutions as first steps to take an active role in reducing climate change and harmful emissions and pollutants. In accordance with the resolutions, Boulder County has inventoried the sources and quantities of its greenhouse gas emissions (GHG) and thus set benchmarks and goals for emission reductions. The inventory has revealed that it is impossible to reach Boulder County's original goal of meeting the Kyoto Protocol standard of reducing greenhouse gas emissions to 7 percent below estimated 1990 County emission levels. However, Boulder County is working to revise goals and objectives to meet the most aggressive attainable standards.
To affect climate change, we all must do our part to reduce greenhouse gas emissions. Boulder County is committed to finding ways to meet our growing energy demand while protecting the environment and stimulating the economy. We are also committed to making sure that our residents have the information and resources necessary to use less energy, save money and make the best possible energy choices. This includes knowing how to pick the most energy efficient products and appliances, improve the efficiency of homes and commercial buildings, use alternative transportation and much more.
Emissions Sources in the United States
Where do greenhouse gases come from? It is a well-researched fact that the combustion of fossil fuels releases greenhouse gases (GHG), namely carbon dioxide (CO2), into the atmosphere, causing global surface temperatures to increase.
Methane and nitrous oxide are often associated with livestock and agriculture. The U.S. Department of Energy provides the following data regarding carbon dioxide emissions:
Residential Sector
Residential carbon dioxide emissions represented 21 percent of U.S. energy-related carbon dioxide emissions in 2004. The residential sector’s pro-rated share of electric power sector emissions accounts for more than two-thirds of all emissions in the residential sector. Natural gas accounted for 22 percent, and petroleum (mainly distillate fuel oil) represented 8.9 percent.
Commercial Sector
Commercial sector carbon dioxide emissions accounted for about 17 percent of total energy-related carbon dioxide emissions in 2004, of which 78 percent is the sector’s pro-rated share of electricity-related emissions. Natural gas contributes 16 percent and petroleum 6 percent of the sector’s emissions.
Industrial Sector
Industrial sector emissions accounted for 29 percent of total U.S. energy-related carbon dioxide emissions in 2004. In terms of fuel shares, electricity consumption was responsible for 38 percent of total industrial sector emissions, natural gas for 26 percent, petroleum for 26 percent, and coal for 10 percent.
Transportation Sector
Carbon dioxide emissions from the transportation sector, accounted for 33 percent of total U.S. energy-related carbon dioxide emissions in 2004. Almost all (98 percent) of transportation sector emissions result from the consumption of petroleum products: motor gasoline at 60 percent of total transportation sector emissions; middle distillates (diesel fuel) at 22 percent; jet fuel at 12 percent of the total; and residual oil (i.e., heavy fuel oil, largely for maritime use) at 2.8 percent of the sector’s total emissions. Motor gasoline is used primarily in automobiles and light trucks, and middle distillates are used in heavy trucks, locomotives, and ships.
For more information, visit the U.S. Energy Information Administration.
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