11 July 2007

The US Climate Change Science Program (CCSP) released a Synthesis and Assessment (S&A) report titled “Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations, and Review of Integrated Scenario Development and Application”. The report provides a new long-term global reference for greenhouse gas (GHG) stabilization scenarios, and an evaluation of the process by which scenarios are developed and used.

Four scenarios are examined, needed to stabilize CO2 concentrations at 450 ppm, 550 ppm, 650 ppm, and 750 ppm. The report also includes a reference scenario where no new climate goals are set after the Kyoto Protocol expires and after the United States meets its greenhouse gas intensity goals, both of which are scheduled for 2012. Three different modeling groups independently examined each of the five scenarios.

The report concludes that to stabilize greenhouse gases concentration will require a transformation of the global energy system, reducing fossil fuel use, and reducing the growth in demand for energy. All of the scenarios found that GHG emissions reductions were achieved at the lowest cost by the electric power industry, using such technologies as renewable energy, nuclear power, and CO2 capture and storage. Other sectors of the economy—including transport, industry, and buildings—could achieve emissions reductions through the use of energy efficiency, biomass energy and biofuels, and electricity generated from low-carbon sources.

Under the most stringent scenarios, GHG emissions begin to decline immediately or within a few decades, while the less stringent scenarios result in peak emissions late in this century or beyond, causing Earth’s atmosphere to increase its heat-trapping ability by a factor of 2.5. The reference scenario projects an increase in the heat-trapping ability of Earth’s atmosphere by a factor of 3 to 4 by 2010.

CCSP was established by President Bush in 2002 to integrate federal research on global environmental change at 13 federal agencies, and to provide the nation with science-based knowledge to manage the risks and opportunities of climate change. The report has been coordinated by the US Department of Energy (DOE).

Source: US Climate Change Science Program