WASHINGTON — The Environmental Protection Agency is expected to act for the first time to regulate carbon dioxide and other greenhouse gases that scientists blame for the warming of the planet, according to top Obama administration officials. The decision, which most likely would play out in stages over a period of months, would have a profound impact on transportation, manufacturing costs and how utilities generate power. It could accelerate the progress of energy and climate change legislation in Congress and form a basis for the United States’ negotiating position at United Nations climate talks set for December in Copenhagen. The...