The United States should accommodate millions of refugees who will be forced to flee disasters and other effects of a changing climate, according to a task force report released Wednesday.   The study, under the auspices of Refugees International, which advocates for displaced people around the word, argues that the United States, as the traditional biggest carbon emitter, “has a special responsibility to lead on issues of climate change, migration and displacement.”  As many as 200 million people worldwide annually will likely need humanitarian assistance due to a changing climate by the year