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.

We have arrived at a moment of decision. Our home - Earth - is in grave danger. What is at risk of being destroyed is not the planet itself, of course, but the conditions that have made it hospitable for human beings.

For a long time, the scientists have been telling us global warming increases the temperature of the top layer in the ocean, and that causes the average hurricane to become a lot stronger. So, the fact that the ocean temperatures did go up because of global warming, because of man-made global warming, starting around in the '70s, and then we had a string of unusually strong hurricanes outside the boundaries of this multi-decadal cycle that is a real factor; there are scientists who point that out, and they're right, but we're exceeding those boundaries now.

Global warming is real and human activity is the main cause. The consequences are mainly negative and headed toward catastrophic, unless we act. However, the good news is that we can meet this challenge. It is not too late, and we have everything we need to get started.

You know there's an old african proverb that i made up: "If you want to go quickly, go alone. If you want to go far, go together."

I remain optimistic that ultimately free speech and a free press where individuals have access to the dialogue will have a self-correcting quality.

You can push your local communities to adopt more sustainable sources of energy and environmentally-friendly practices.