Reuters: Carbon markets could one day help support the development of U.S. high-speed commuter rail lines, the head of the Chicago Climate Exchange (CCX) said on Tuesday. The United States has lagged many countries in building high-speed trains that emit a smaller volume of planet-warming gases per passenger than auto or jet travel while also dramatically cutting down on travel time compared to cars and regular trains. China, for instance, unveiled last summer a new “bullet” train from …