Airplane travel is nature's way of making you look like your passport photo.

Today I challenge our nation to commit to producing 100 percent of our electricity from renewable energy and truly clean carbon-free sources within 10 years.

Pollution should never be the price of prosperity.

When it comes to climate, we can all make a big difference. At the most basic level, don't let denial go unchallenged and win the conversation on climate.

What's at risk [in 100 years] if we do not take action, truly is the survival of civilization as we know it... Literally that is the case. We have seen global warming so far of just a little bit less than one degree Celsius and look at what's happened. Superstorm Sandy. Boulder Colorado. All these fires. Hurricane Irene one year before.

During my service in the United States Congress, I took the initiative in creating the Internet. I took the initiative in moving forward a whole range of initiatives that have proven to be important to our country's economic growth and environmental protection, improvements in our educational system.

We're all capable of mistakes, but I do not care to enlighten you on the mistakes we may or may not have made.