Second U.S. Climate Change Science Program Report Issued
The U.S. Climate Change Science Program (CCSP) today announced the release of the second in a series of 21 Synthesis and Assessment reports.
The
U.S. Climate Change Science Program (CCSP) today announced the release of the second in a series of 21 Synthesis and Assessment reports.
The report is titled “Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations, and Review of Integrated Scenario Development and Application,” and provides a new long-term, global reference for greenhouse gas stabilization scenarios and an evaluation of the process by which scenarios are developed and used.
This report is presented in two parts. Part A, “Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations,” uses computer-based scenarios to evaluate four alternative stabilization levels of greenhouse gases in the atmosphere and the implications to energy and the economy for achieving each level. Although these scenarios should not be considered definitive predictions of future events, they provide valuable insights for decision-makers.
Part B, “Global-Change Scenarios: Their Development and Use,” examines how scenarios have been developed and used in global climate change applications, evaluates the effectiveness of current scenarios, and recommends ways to make future scenarios more useful.
This report uses a reference case and four scenarios that evaluate the implications of stabilizing greenhouse gases. The reference case assumes that no new measures are instituted to limit emissions.
In the four stabilization scenarios, global greenhouse gas concentrations are limited in the atmosphere to 450 parts per million (ppm), 550 ppm, 650ppm and 750ppm. The report shows that stabilizing the concentration of carbon dioxide (CO2), the most important greenhouse gas released by human activities, requires global emissions to peak in the 21st century and then decline indefinitely thereafter for all four stabilization levels. Non-CO2 greenhouse gas emissions, such as methane and nitrous oxide, played an important role in each level.
Part A includes stabilization scenarios for the six primary anthropogenic greenhouse gases - CO2, nitrous oxide, methane, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride – and it used updated economic and technological data and new tools for scenario development. However, the report highlights that the outcomes, estimated over a 100-year period, reflect simplified assumptions about economic, societal, and political behavior, including a presumption of perfect economic efficiency and policy agreement among nations.
Part B of the report concludes that scenarios can support decision-making by providing insights regarding key uncertainties, including future emissions and climate as well as other environmental and economic conditions.
Federal agencies plan to deliver the remaining 19 reports over the course of the next year to increase scientific understanding related to climate change.
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