 Aug. 22, 2008 - Two-thirds of U.S. industries overlook 75% of their total greenhouse gas emissions using current calculation methods, say researchers at Carnegie Mellon University.
A little background: Accepted frameworks for tracking industry carbon emissions rely on "tiers" of increasingly broad scope. Tier one generally includes emissions by the company's own activities, such as burning gasoline in fleet vehicles or natural gas in its facilities. The second tier boundary expands to include emissions from electricity and steam purchased by the company. Tier three includes all other emissions, including the entire supply chain of goods and services.
Unfortunately, most companies reporting their greenhouse gas emissions opt to use only tier one or the tier two boundary - leaving significant amounts of emissions unaccounted for, the researchers say. The average industry has only 14% of its total greenhouse gas emissions in tier one and 12% in tier two for a total of 26%.
For example, only 6% of the publishing industry's greenhouse gas emissions result from its tier one and tier two uses of petroleum products and electricity. Large emissions from electricity and paper in the supply chain ("tier 3") don't even make it into the books, according to the report.
To highlight the disparity, Carnegie Mellon researchers H. Scott Matthews, Chris T. Hendrickson and Christopher L. Weber developed a new calculation method that estimates the amount of greenhouse gas emissions across all tiers of the entire supply chain for all industries. The researchers have helped develop a website that analyzes carbon footprints and other impacts for different economic sectors in the U.S. economy.
"By far, most companies are pursuing very limited footprints — toe prints really — instead of comprehensive ones," says Matthews, an associate professor of civil and environmental engineering and engineering and public policy.
The Carnegie Mellon report appeared in the Aug. 15 issue of Environmental Science & Technology. |
