This morning, his lecture was a science-heavy discussion of the history of natural and human-caused climate change and the effects we are seeing now, but with some "holy cow" points that really made me sit up and take notice.
Humans are in total control of the global climate now, he said. So much so that we'll never have another ice age if we don't want to. "A thimbleful of CFCs will stop an ice age," he said. The climate is delicate enough that the massive contributions - for better or for worse - that humans have made has put us in complete control.
The business-as-usual scenario for climate change is that we'll see an approx 3 degree Celsius change in temperature and extinction of 25-50% of species. The alternative scenario (I don't think he articulated very well exactly what that means): Keep average global warming temperature change to around 1 degree Celsius and only about 10% of species may go extinct.
Of course we don't have to do anything about climate change, but the most devastating results - if we continue with a business-as-usual scenario - will include massive species extinction and rising sea levels that will affect major cities up and down the East Coast and pretty much all of Florida. The economic and social devastation is hard to imagine.
One question from the audience was when? When will the ice caps melt? How long do have?
Answer: Hard to say. The ice tends to melt slowly and then collapse. But if we keep on doing what we're doing and don't clean up our act, they'll likely melt this century.
So what do? Hansen had several ideas, including restructuring the way utilities make money so that they emphasis clean technologies and efficiency rather than be made for the amount of electricity they sell. "We can't expect them to stop make money, so we have to change the rules of how they make money."
He also thinks every political candidate should be asked whether they agree with the following:
- Moratorium on all coal-fired power plants unless they can capture and sequester CO2
- Incentives for renewable energy
- Incentives and massive push for efficiency