‘ANNAPOLIS, Md. \u2014 When Lisa P. Jackson announced at the end of last year that she was stepping down as the administrator of the Environmental Protection Agency, President Obama faced a choice. He could play it safe by appointing her deputy or he could confront Congress head-on and signal a strong commitment to tackling climate change by appointing the agency\u2019s head of air quality, Gina McCarthy.’<\/p>\n