Watch Democracy Now! interview with James Hansen.

Here's a few excerpts from the interview transcript;
"...having a cap-and-trade-with-offsets agreement, which is analogous to the Kyoto Protocol, which was disastrous. Before the Kyoto Protocol, global emissions of carbon dioxide were going up one-and-a-half percent per year. After the accord, they went up three percent per year. That approach simply won’t work....

We began in 2002 to get this spectacular data from the gravity satellite, which measures the gravitational field of the earth with such a high precision that you can get the mass of the Greenland ice sheet and the Antarctic ice sheets. And what we see is that in 2002 to 2005, we were losing mass from Greenland at a rate of about 150 cubic kilometers per year. Well, now that’s doubled to about 300 cubic kilometers per year. And likewise, the mass loss from Antarctica has also doubled over that time period....

So we can see that we’re moving toward a tipping point where those ice sheets will begin to disintegrate more rapidly, and sea level will go up. And that’s one of the bases, and others, for saying that a safe level of carbon dioxide is actually less than what we have now.....

But if you look at what governments are doing, the reason that you know that the kind of accords they’re talking about are not going to work is because, look at what they’re actually doing. The United States had just agreed to have a pipeline from the tar sands in Canada to the United States....

They’re among the dirtiest fossil fuels on the planet. There’s oil mixed in the ground with the sand. You have to cook that material to get oil to drip out of it. That takes a lot of energy to cook it. And then you end up with oil, which also has carbon. Then you burn the oil, and you get more carbon. So it’s much more carbon-intensive than oil itself....

There’s much more there in tar sands than even in Saudi Arabia....

So the point is, we’re going to have to move to the energy system beyond fossil fuels. We need to drive the economic system so that we move to a clean energy future. And there are many other advantages in doing that: cleaning up the atmosphere, cleaning up the ocean. You get—the mercury and arsenic and all these pollutants are coming from fossil fuels. So we need to get off this fossil fuel addiction. And the way you do that is to put a gradually rising price on the carbon emissions. "