The report, "Climate Change Indicators in the United States," looks at 24 key indicators that show how climate change impacts the health and environment of the nation's citizens.
"These indicators show us that climate change is a very real problem with impacts that are already being seen," said Gina McCarthy, assistant administrator for EPA's Office of Air and Radiation.
The report finds that greenhouse gas emissions from human activities are increasing. Between 1990 and 2008, there has been about a 14 percent increase in emissions in the United States. Carbon dioxide accounts for most of the nation's emissions and most of this increase. Electricity generation is the largest source of greenhouse gas emissions in the United States, followed by transportation, the report finds. Emissions per person have remained about the same since 1990.
Worldwide, emissions of greenhouse gases from human activities increased by 26 percent from 1990 to 2005, according to the report, which is based on data collected by federal government agencies and universities.
The generators at the Keystone power plant in Pennsylvania are among the largest coal-fired units in the United States. As all coal-fired power plants do, Keystone emits greenhouse gases. (Photo by Doug Jackson)
Emissions of carbon dioxide, which account for nearly three-fourths of the total, increased by 31 percent over this period. As in the United States, the majority of the world's emissions are associated with energy use.
Concentrations of carbon dioxide and other greenhouse gases in the atmosphere have risen substantially since the beginning of the industrial era. "Almost all of this increase is attributable to human activities," the report states. "Historical measurements show that the current levels of many greenhouse gases are higher than any seen in thousands of years, even after accounting for natural fluctuations."
Average temperatures are rising. Seven of the top 10 warmest years on record for the continental United States have occurred since 1990.
Tropical cyclone intensity has increased in recent decades. Six of the 10 most active hurricane seasons have occurred since the mid-1990s.
Sea levels are rising. From 1993 to 2008, sea level rose twice as fast as the long-term trend. The report finds that along the U.S. coastline, sea level has risen the most relative to the land along the Mid-Atlantic coast and parts of the Gulf Coast. Sea level has decreased relative to the land in parts of Alaska and the Northwest.
Glaciers are melting. Loss of glacier volume appears to have accelerated over the last decade.
The portion of North America covered by snow has generally decreased since 1972, although there has been much year-to-year variability, the report states. Snow covered an average of 3.18 million square miles of North America during the years 2000 to 2008, compared with 3.43 million square miles during the 1970s.
The frequency of heat waves has risen steadily since the 1960s. The percentage of the U.S. population impacted by heat waves has also increased.
McCarthy says the information included in this report will inform future policy decisions and will help evaluate the success of climate change efforts.
"The actions Americans are taking today to save energy and reduce greenhouse gas emissions will help us solve this global challenge," said McCarthy.
The data used in the report were collected by several government agencies, academic institutions, and other stakeholder organizations. As new data and information become available, EPA will update and broaden the indicators in future reports.
Click here for the Climate Change Indicators report.
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