Environmental Protection Agency Administrator Gina McCarthy couldn't give much detail in only 140 characters, but she could have at least answered more than nine questions during her first-ever Twitter "office hours."

Two of the nine were from Obama administration officials, Secretary of Transportation Anthony Foxx and Secretary of Energy Ernest Moniz. Another question was about the Boston Red Sox, to which McCarthy answered "Go Sox!"

That leaves six questions about policy.

McCarthy responded to two questions by pointing to Obama's recent climate plan. With no successful international climate change program that the U.S. could look toward for guidance, McCarthy was left to refer her questioner to Obama's plan, saying "No lost causes  just opportunities to work together for the health of the planet."

The toughest question McCarthy was asked was if global warming could be a naturally occurring event. She responded by admitting the climate has changed in the past, but said that recent warming is "mostly due to human emissions," and provided a link to an EPA report saying so.

McCarthy also responded to a question about giving advice to young people considering a job in environmental studies, saying, "Go for it. Know your science. It's not just a job  it's a career that matters."

Another questioner asked about renewable energy, prompting McCarthy's observation that "green infrastructure is not just for climate, good for water quality and local economies." Well, except for all the jobs lost from green energy and other companies going belly up.

The final remaining question was about protecting water. McCarthy offered no actual answer but said it must be part of EPA's solution.