I wanted to take a very quick break from my travels not to ask for money and not to talk politics, but just to pass on some thoughts about two big global challenges which need to be on our minds: HIV/AIDS and climate change.

This week, Teresa and I experienced an up close and personal reminder of how far the world has yet to travel to defeat HIV/AIDS. Talking with people in poverty stricken KwaNgcolosi near Hillcrest in Durban, South Africa, we saw both the most inspiring and the most heartbreaking realities of a global struggle to defeat a global scourge.

We met orphaned children left with no choice but to assume adult responsibilities, caring for their young brothers and sisters. We met single mothers scratching out subsistence in mud houses, their husbands lost to a horrific disease. I have to tell you, experiences like this have an impact on you.

I didn't want to wait until I got back to the United States to say something to you, because tomorrow is World AIDS Day - and it needs to be a day of action. Challenge Washington to stop blocking better educational efforts and stop putting ideology before science. Demand that American leadership help convince nations like South Africa not to repeat our shameful denial of HIV/AIDS in the 1980s - and to commit their countries to saving lives not saving face. There is no fixing a problem political leaders refuse to admit exists.

There's something else - and I'll have much more to say about this when I'm back. I'll be leading - with Senator Boxer - a Senate delegation to Bali in December to the global conference where work will start on a new international climate change treaty. We can't wait until we have a new president; we need to get moving now. The world simply can't solve these problems without American participation and leadership. Stay tuned.

Bottom line - these are the huge global issues that demand that America be America again, and that we lead by example - and that we lead now.