For more than five years, I have been fortunate to have Heather Zichal as a trusted advisor. She crafted my energy and climate change agenda in the 2008 campaign, then again on my Presidential transition, and as my top energy and climate advisor at the White House, she has been a strong and steady voice for policies that reduce America's dependence on foreign oil, protect public health and our environment, and combat the threat of global climate change. Heather has overseen some of our biggest achievements in energy and climate change, including establishing historic new fuel economy standards that save consumers money, reducing mercury pollution from power plants to keep our kids safe, supporting the growth of homegrown clean energy that creates good new jobs, and enacting my Climate Action Plan that will help us leave a safer planet for our children. Above all, Heather's efforts have proven that strengthening America's energy security does not have to be a choice between economic growth or good environmental stewardship -- it can mean both. I am grateful for Heather's service, and I wish her the best in her next endeavors.