New York Times: In the first quarter of 2012, energy-related carbon dioxide emissions in the US were the lowest recorded for the same time period since 1992, writes Rachel Nuwer for the New York Times. Although some of the decline can be attributed to the mild winter and a reduced demand for gasoline, the biggest factor was that the drop in natural gas prices due to continuing extraction from the Marcellus shale led to reduced use of coal. Natural gas is more efficient than coal in generating electricity, and it emits less carbon per unit of energy. Michael Mann, a climate scientist at the Pennsylvania State University, however, points out that the process of extracting natural gas can cause other problems, including the escape of methane into the atmosphere and contamination of the groundwater. Experts agree that wind and solar energy are superior to any fossil fuel when it comes to emissions, and they should continue to be pursued.