5.802 billion

Metric tons of carbon-dioxide emissions from fossil fuels generated in this country in 2008, down from 5.967 billion metric tons of carbon dioxide in 2007, according to new preliminary estimates from the Energy Information Administration. The 2.8 percent decline is the largest the EIA has measured since it has tracked CO₂ emissions. It's worth noting that even with this decline, since 1990, total U.S. energy-related CO₂ emissions have climbed by 15.9 percent.

The recession has been a major factor in the emissions reduction, as economic activity in this country has fallen off and demand for oil slackened. (Oil-related emissions slid by 6 percent year over year.)

Residential CO₂ emissions fell by 1.1 percent in 2008. Even though heating degree-days rose by 5.6 percent last year, the summer was cooler than in 2007, resulting in a cooling-degree-days drop of 8.7 percent.

Want to keep limit your own energy use? Check out our buyer's guide to air conditioning, use our calculator to determine how big an air conditioner you need, learn how to keep your cooling costs down this summer,  and read up on ceiling fans, portable air conditioners, and split-ductless AC systems.