The Sierra Club's Cool Cities campaign encourages cities to make a commitment to stopping global warming by signing the U.S. Mayors' Climate Protection Agreement. Started in 2005, the effort has recently seen a spike in membership as more city officials become wise to the benefits of energy conservation. To date just over 1,000 cities across the country have taken the pledge to move forward with innovative energy solutions that curb global warming.\r\n\r\nAt the website <a href="http:\/\/coolcities.us">coolcities.us.<\/a> you can not only see if your city is on the list but also what specifically your leaders are doing to make your city more efficient. For instance, Charlotte, N.C., can tout a large municipal fleet of hybrid cars, while Blacksburg, Va., has started replacing traffic lights with LEDs and doing an energy audit of town buildings and making needed changes to reduce their energy use.