WASHINGTON – President Barack Obama signaled his willingness to tackle climate change with his pick of Gina McCarthy to lead the Environmental Protection Agency, one of three major appointments he announced Monday.

A 25-year veteran of environmental policy and politics, McCarthy has worked for Republicans and Democrats, including Obama’s presidential rival, Mitt Romney, who tapped her to help draft state plans for curbing the pollution linked to global warming. Along with McCarthy, Obama nominated MIT nuclear physicist Ernie Moniz to lead the Energy Department and Wal-Mart’s Sylvia Mathews Burwell to head the budget office.

McCarthy, 58, a Boston native, has led the EPA’s air pollution division since 2009, ushering in a host of new rules targeting air pollution from power plants, automobiles, and oil and gas production.