SACRAMENTO, Calif. — California plans to install a network of computerized monitors to measure methane emissions from regions that are home to dairy ranches, farms, landfills and other sources. It will be the first network of its kind in the United States and will help the state take another step toward reducing emissions of the gases related to global warming. By May, seven devices about the size of a personal computer will be placed in regions of the state where methane emissions are believed to be the highest. Those include the farm fields of the Sacramento and San Joaquin valleys...