Why are this week's new carbon rules critical to our future?
As EPA's Gina McCarthy described it, "We have a moral obligation to the next generation to ensure the world we leave is healthy & vibrant."
Others might be more direct: It's climate change, stupid!
I recently interviewed CBS 60 Minutes correspondent Lesley Stahl and she shared her emotional reaction to climate change. She witnessed the rapid ice melt in Greenland and reported about it for Years of Living Dangerously, the documentary series on climate change.
"I thought global warming needed an alarm bell rung before I went, but it was extremely emotional for me to see first hand the ice melt," says Stahl. "Knowing what it's going to do for the rest of the planet."
She's talking primarily about global sea level rises, but there's also the devastation that will occur due to rising temperatures, widespread drought and the increasing frequency of deadly storms like Hurricane Sandy.
Find out more about Stahl's report for the Years of Living Dangerously series here. It's produced by David Cameron and features reports from Tom Friedman, Matt Damon, Jessica Alba and Don Cheadle.
The interview was recorded at the Foothill College Celebrity Forum Series in Silicon Valley on May 15, 2014.
Here's my interview with Lesley Stahl on Barbara Walters' legacy.