Bloomberg: The price of carbon emissions must rise to US$180 a metric ton by 2030 to meet greenhouse gas reduction targets, the executive director of the International Energy Agency said. “An energy revolution is necessary,” Nobuo Tanaka said at the Asian Oil & Gas Conference in Kuala Lumpur. European Union carbon dioxide allowances for December traded US$18.82 a ton today on the European Climate Exchange in London. United Nations scientists say greenhouse-gas output should peak by …