My name is Dan Weiss, I'm a Senior Fellow working on clean energy and global warming here at the Center for American Progress. We got submitted a number of questions about clean energy and global warming from our Facebook page.

Our first questions is from Sandi Smith from Austin, Texas.

"How do we explain that global warming is really happening to people who may be doubters?"

That's a great question, Sandi. What I think is most effective is to talk about real world impacts that we're already seeing. For example, this past July was the hottest month on record. This has been the hottest year on record, following the hottest decade on record. And the decade before that--the 1990s--was until then the hottest decade on record. In addition, one can look to Russia, where they are having the hottest weather on record also. It's caused a huge decline in their wheat crop, and they aren't going to be able to export any wheat. It's important that you understand the difference between weather and climate. Weather is what we see everyday, climate is the long-term trend. When you look at the long-term trend, it shows warming and an increase in extreme weather events.

Our next questions is from Rob Stanfield in Rochester, New York.

"How does the carbon cap and trade legislation differ from the highly successful acid rain effort?"

Great question, Rob. First, a little background. In 1990, President George H.W. Bush proposed to reduce the the pollution from coal-fired power plants that cause acid rain by establishing a cap and trade program. Rather than make every power plant make the same level of reductions, we made a system where the overall amount of pollution had to come down. Power plants that could make more reductions would get paid to make them by power plants who couldn't afford to make reductions. That way, we accomplished the goal at about one-third the cost that people predicted.

Now, when it comes to global warming pollution, the same system actually passed the House of Representatives. But there's a couple differences. First, it covers the entire industrial economy, the larger sources of pollution, which include power plants, transportation fuels, and industrial sectors. Second, there's a lot of opposition to it, even though such a program worked so well under acid rain. We're continuing to try to push this concept forward, because we think its a very cost-effective way to reduce pollution, drive investment into cleaner energy sources, create jobs, and increase our national security by reducing oil use.

Our next question is from Gary Dees of Tyler, Texas. He wants to know:

"What kind of energy bill can pass without a provision that reduces global warming pollution, but that still makes some difference?"

Well, Gary, that's a great question. It's pretty clear that there won't be global warming legislation passed by Congress in 2010 that will reduce global warming pollution. Instead, there's a possibility we could do some leaner clean energy programs that would reduce oil use by boosting investment in natural gas trucks, by increasing incentives for electric vehicles, and by increasing incentives for home efficiency retrofits. All three of these measures would also reduce global warming pollution. The World Resources Institute did an interesting study that showed if you just used existing legal authority and actions that the states are planning to undertake, you could reduce about two-thirds of the global warming pollution that President Obama committed to by 2020. The challenge is getting that last third, and then getting further reductions after 2020. To do that, Congress is going to have to pass legislation to reduce global warming pollution.