What science has to say about Obama's speech

In his speech Tuesday, President Obama said he wanted one day to tell his grandchildren that "Yes, we did" do everything possible to avert climate change. He said his "all of the above" energy policy had brought America "closer to energy independence than we have been in decades."

"One of the reasons why is natural gas," Obama said. "If extracted safely, it's the bridge fuel that can power our economy with less of the carbon pollution that causes climate change." He added, "We have to act with more urgency because a changing climate is already harming western communities struggling with drought and coastal cities dealing with floods."

On this week's Climate Cast, we talk with a NASA scientist about the president's remarks on climate change.