Climate Central: The carbon dioxide that belches from tailpipes and smokestacks is a proven greenhouse gas that has been driving global temperatures more or less steadily upward over the past century. But the heat that leaks directly into the environment from hot exhaust pipes, boilers and chimneys has also contributed to temperature increases in some places, according to a study published Sunday in Nature Climate Change, especially in winter-- not directly, but rather because the waste heat may be altering the flow...