"the three most important environmental posts in the federal government" are all vacant; also, the White House Office of Energy and Climate Change Policy has been eliminated as a standing White House Office

Salazar departure leaves ‘green’ posts vacant - The Washington Post

With Interior Secretary Ken Salazar’s announcement Wednesday that he intends to resign, the Obama administration finds itself in exactly the same place it was four years ago: looking to fill the three most important environmental posts in the federal government.

The Interior Department, the Environmental Protection Agency and the National Oceanic and Atmospheric Administration all have openings at the top, while the administration has a limited amount of time to press a second-term environmental agenda before the next election cycle begins.
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Heather Zichal, deputy assistant to the president for energy and climate change, is the highest ranking adviser. She was deputy to Carol Browner, who was not replaced.
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Thomas L. Strickland, who served as Salazar’s assistant secretary and now is a partner at the law firm WilmerHale, said global warming remains “the dominant issue of our time” when it comes to the environment.

White House Office of Energy and Climate Change Policy - Wikipedia, the free encyclopedia

The White House Office of Energy and Climate Change Policy is a new government entity in the United States created by President Barack Obama by Executive Order, by-passing Congress. Its first director is Carol Browner, who was Administrator of the Environmental Protection Agency for the eight years of the Bill Clinton administration. The office was created in order to coordinate administration policy on energy and climate change...In April 2011 it was reported that Congress would no longer fund the office in the 2011 budget.[4] On March 2, 2011 the White House announced that the climate and energy work done by the office would move under the umbrella of the Domestic Policy Council, thereby eliminating it as a standing White House Office.