What Are Greenhouse Gases?
Gases that trap heat in the atmosphere are often called greenhouse gases. Some greenhouse gases such as carbon dioxide occur naturally and are emitted to the atmosphere both through natural processes and human activities. Other greenhouse gases (e.g., fluorinated gases) are created and emitted solely through human activities. The following principal greenhouse gases enter the atmosphere because of human activities:
Carbon Dioxide (CO2)
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). Carbon dioxide is also removed from the atmosphere (or sequestered) when it is absorbed by plants as part of the biological carbon cycle. About 75% of all greenhouse gases emitted globally are carbon dioxide.
Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.
Nitrous Oxide (N2O)
Nitrous oxide is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.
Hydrofluorocarbons (HCFCs), perfluorocarbons, and sulfur hexafluoride are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for ozone-depleting substances (i.e., chlorofluorocarbons [CFCs], HCFCs, and halons). These gases are typically emitted in smaller quantities, but because they are potent greenhouse gases, they are sometimes referred to as High Global Warming Potential gases (High GWP gases).
How Much GHG Do We Generate?
The United States is responsible for approximately 25% of the world's total emissions. Idaho is one of the states with the lowest emissions of carbon dioxide (47th); however, Idaho's gross greenhouse gas emissions increased approximately 31% from 1990 to 2005, while national emissions rose by only 16% over the same period. Activities in Idaho accounted for approximately 37 million metric tons of gross carbon dioxide equivalent (CO2e). Idaho's primary sources by sector are transportation, agriculture, residential, commercial and industrial fuel use, and electricity consumption.
Idaho's GHG Emissions Inventory Report
The Center for Climate Strategies (CCS) prepared the Idaho Greenhouse Gas Inventory and Reference Case Projections 1990-2005 Report for DEQ through an effort of the Western Regional Air Partnership (WRAP). The report contains an inventory and forecast of the state’s greenhouse gas emissions from 1990 to 2020 to provide an initial comprehensive understanding of Idaho’s current and possible future greenhouse gas emissions. The information presented provides the state with a starting point for revising the initial estimates as improvements to data sources and assumptions are identified. The state intends to update and improve upon this report as more data become available.