According to the document, which has already been circulated to millions via its posting on the Internet, "This document provides technical support for the endangerment analysis concerning greenhouse gas (GHG) emissions that may be addressed under the Clean Air Act. The primary GHGs of concern directly emitted by human activities include carbon dioxide CO2, methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6)."
According to the report, "The current (year 2005) CO2 concentration is 379 parts per million (ppm) and has recently been increasing by about 1.9 ppm per year. Current ambient concentrations of CO2 and other GHGs remain well below published thresholds for any direct adverse health effects, such as respiratory or toxic effects. . .
"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level. Global mean surface temperatures have risen by 0.74°C (1.3ºF) over the last 100 years. The rate of warming over the last 50 years is almost double that over the last 100 years. . .
"Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. Climate model simulations suggest natural forcings alone (e.g., changes in solar irradiance) cannot explain the observed warming. Likewise, North America’s observed temperatures over the last century can only be reproduced using model simulations containing both natural and anthropogenic forcings. . .
"Observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases. Observations show that climate change is currently impacting the nation’s ecosystems and services in significant ways. . .
"The range of projected ambient concentrations of CO2 and other GHGs will remain well below published thresholds for any direct adverse health effects, such as respiratory or toxic effects. . . "All of the U.S. is very likely to warm during this century, and most areas of the U.S. are expected to warm by more than the global average. The average warming in the U.S. is projected to exceed 2°C (3.6°F) by the end of the century, with 5 out of 21 models from IPCC projecting average warming in excess of 4°C (7.2°F). . . By the end of the century, sea level is projected to rise between 0.18 and 0.59 meters relative to around 1990. . . "
The report indicates that the Global and U.S. Impacts Associated with Future Climate Change include:
- Risk increases with increases in both the rate and magnitude of climate change. Climate warming may increase the possibility of large, abrupt, and unwelcome regional or global climatic events (e.g., disintegration of the Greenland Ice Sheet or collapse of the West Antarctic Ice Sheet). . .
- Severe heat waves are projected to intensify in magnitude and duration over the portions of the U.S. where these events already occur. . .
- The IPCC projects with virtual certainty declining air quality in U.S. and other world cities due to warmer and fewer cold days and nights and/or warmer/more frequent hot days and nights over most land areas. . .
- Moderate climate change in the early decades of the century is projected to increase aggregate yields of rainfed agriculture by 5-20% in the U.S., but with important variability among regions. . .
- Disturbances like wildfire and insect outbreaks are increasing and are likely to intensify in a warmer future with drier soils and longer growing seasons. . .
- Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution. . .
- Climate change will constrain over-allocated water resources in the U.S., increasing competition among agricultural, municipal, industrial, and ecological uses. . .
- Climate change is likely to affect both U.S. energy use and energy production; physical infrastructures; institutional infrastructures. . .
- Disturbances such as wildfire and insect outbreaks are increasing in the U.S. and are likely to intensify in a warmer future with drier soils and longer growing seasons.
- Climate change impacts in certain regions of the world may exacerbate problems that raise humanitarian and national security issues for the U.S.
Section 8 of the report describes how climate change may increase exposure to concentrations of ozone and, in some cases, PM with associated impacts on public health and welfare in the U.S. The report indicates, "Assuming constant population and dose-response characteristics, ozone related deaths from climate change in the U.S. are projected to increase by approximately 4.5% from the 1990s to the 2050s (under the IPCC A2 scenario) (Field et al., 2007; Bell et al., 2007; Knowlton et al., 2004). According to the IPCC (Field et al., 2007), the 'large potential population exposed to outdoor air pollution, translates this small relative risk into a substantial attributable health risk.' In New York City, health impacts could be further exacerbated by climate change interacting with urban heat island effects (Field et al., 2007). . ."
Access the Endangerment document (click here). Access the EPA Docket with links to the many other background materials (click here). Access EPA's website on the ANPR with additional information (click here). [*Climate]
No comments:
Post a Comment