In 2007, the city aimed to reduce greenhouse gas emissions by 30 percent of the 2005 levels by 2030. Emissions were reduced by 13 percent between 2007 and 2011. This was attributed to a 26 percent decrease in carbon intensity present in the city's electrical supply during this period as a result of more efficient power plants and increased use of renewable energy. Con Edison also stepped in to curb the threat of fugitive sulfur hexafluoride leakage in its electricity transmission and distribution system, which further lowered emissions by 3 percent.