The US EPA just released an excellent report on climate change indicators in the US. In this first of a series of Planetsave posts summarizing the report, we look at greenhouse gases.
The US Environmental Protection Agency just released Climate Change Indicators in the U.S., a report showing “compelling evidence that the composition of the atmosphere and many fundamental measures of climate in the United States are changing.”
Although there is surely much more happening as a result of climate change than what is in this report, the range of indicators presented by the EPA here and their significance for humans and life everywhere on the planet are profound.
Rather than present everything in one bulky post, I am reposting key summary findings from the EPA in a series of posts related to different specific topics. To start with, here are summary findings concerning greenhouse gases, directly quoted from the EPA’s “Summary of Key Findings” [PDF]:
U.S. Greenhouse Gas Emissions. In the United States, greenhouse gas emissions caused by human activities increased by 14 percent from 1990 to 2008. 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. Emissions per person have remained about the same since 1990.
Global Greenhouse Gas Emissions. Worldwide, emissions of greenhouse gases from human activities increased by 26 percent from 1990 to 2005. Emissions of carbon dioxide, which account for nearly three-fourths of the total, increased by 31 percent over this period. Like in the United States, the majority of the world’s emissions are associated with energy use.
Atmospheric Concentrations of Greenhouse Gases. 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. 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.
Climate Forcing. Climate or “radiative” forcing is a way to measure how substances such as greenhouse gases affect the amount of energy that is absorbed by the atmosphere. An increase in radiative forcing leads to warming while a decrease in forcing produces cooling. From 1990 to 2008, the radiative forcing of all the greenhouse gases in the Earth’s atmosphere increased by about 26 percent. The rise in carbon dioxide concentrations accounts for approximately 80 percent of this increase.
For more detailed information on greenhouse gases, visit the EPA’s Greenhouse Gases PDF.
Image Credit: Roberto Rizzato ►pix jockey◄ Facebook resident via flickr/CC license
Graph Credit: US EPA’s Greenhouse Gases PDF