There is scientific evidence that demonstrates there is some impact from human activities. However I don't think the evidence is conclusive.

In Maidan Square right now, you see thousands of Ukrainians protesting the Russian occupation of Crimea. So this is a Russian protest by Ukrainians who want their sovereignty. They want their freedom and they're protesting what Russia did in Crimea.

If Vladimir Putin is conscious and aware of his standing in the world economy, he has to understand this aggression in Crimea is not helping the reputation of Russia as a modern nation where you can do business. He's back to the old Soviet ways and a lot of folks are going to hold back and pull back as a result of it. I think he may have second thoughts.

If I am going to pick and choose the laws I defend, I wouldn't be doing my duty as attorney general.

In the midst of our wars in Iraq and Afghanistan, Putin invaded the Republic of Georgia. Let's call it for what it is. Here is Vladimir Putin with a failing Soviet franchise. And when he can't win the hearts and minds of his neighboring nations, he uses energy extortion, masked gunmen and barbed wire.

If we were to impose greater sanctions on economic sectors, I think we could have a significant impact on Putin.

There is scientific evidence that demonstrates there is some impact from human activities. However I don't think the evidence is conclusive.