by Bob Tippee, EditorHere's how to cut emissions of greenhouse gas: Shrink the economy, and burn less coal.These lessons emerge in a March US Energy Information Administration report showing that human-induced emissions of GHGs by the world's favorite global-warming villain fell by more in 2009 than in any year since records began in 1990. Carbon dioxide, the main regulatory target, dominated the 5.8% decline.EIA gives three primary reasons for the lower emissions: economic recession, the particularly heavy setbacks of energy-intensive industries, and fuel-switching by power generators to natural gas from coal, encouraged by falling gas prices.Largely because of economic slowdown, the US ...