EERE Network News - 10/22/08

Carbon dioxide emissions from burning fossil fuels and manufacturing cement have increased 38% since 1992, despite international efforts to reduce emissions, according to DOE's Oak Ridge National Laboratory (ORNL). Carbon dioxide emissions grew from 6.1 billion metric tons of carbon in 1992 to 8.5 billion metric tons in 2007, with the greatest growth in rapidly developing Asian countries such as China and India. In fact, the United States was the largest emitter of carbon dioxide in 1992, but China is now leads the pack. The major human-caused sources of carbon dioxide are energy use, cement manufacture (which releases carbon dioxide when limestone is converted to lime), and deforestation, so the ORNL study accounts for two of the three major sources.

The ORNL study is part of a larger effort to determine the global carbon budget for 2007. That effort, led by the Global Carbon Project, also looks at carbon emissions from land use changes (such as deforestation) and natural "sinks" for carbon dioxide. The world's oceans and trees are large carbon sinks, with oceans removing 25% of all carbon dioxide emissions over the past eight years, and terrestrial sinks removing another 29%. The end result is that the fraction of carbon dioxide in the atmosphere is increasing. In fact, it increased by 2.2 parts per million (ppm) in 2007, which was greater than the 2.0 ppm average growth rate for 2000-2007, and well above the growth rate of 1.5 ppm that held for the previous 20 years. The 2007 increase brought the atmospheric concentration of carbon dioxide to 383 ppm, which is 37% greater than the concentration at the start of the industrial revolution. According to the Global Carbon Project, the present concentration is the highest in at least 650,000 years and is probably the highest for the last 20 million years.