Get people to work together by motivating them as groups, not individuals.
You know what it's like to be part of a crowd. You do what the person next to you is doing, or the person in front; you feel connected, a part of something larger than yourself. That's missing when people try to mitigate climate change--because it seems like nobody else is doing anything. Furthermore, people only do what the crowd is doing, and don't want to do more than that, because it's really hard to see the difference that individual contributions make; it's only communities working together that make a noticable difference.
So harness the power of the crowd. Get people working to combat climate change as communities and groups, not as individuals: hold competitions and rallies to reduce the carbon footprint of a community as a whole, and create competition between communities, to foster team spirit. Also, give people a tangible benefit to their actions, a prize, something they can help their community win--like a new public park, or a tax credit for everyone. And make at least some prize available to any community that accomplishes a certain goal.
Category of the action
Changing public perceptions on climate change
What actions do you propose?
It's not that difficult to find ways of mitigating climate change that can be measured. The first is recycling: Any town that has a certain percentage of its trash go to the recycling plant wins a prize. The town that has the greatest amount go to the recycling plant wins the grand prize--say, even bigger tax breaks for everyone, or even a visit from an NFL team (see below).
Then there's air and water quality, though those will mainly be for businesses like refineries. It's fairly simple to take a sample of the air, or water, and see how many contaminants are in it; when the community as a whole reaches a certain threshold, places that would have contributed to bad air quality (and thus would cut back in order to attain the good air quality) would get a tax cut. This will create peer pressure, if you will, on the plants and businesses, because they'll be encouraging their fellows to work for those cuts.
Who will take these actions?
State governments, mostly. The federal government is too much in debt to take on a program like this.
There is another option, which could be done in addition to the tax cuts given by state governments:
Football teams. EVERY community has places that love football. Teams could offer to come visit the town in their area that improves its carbon footprint by the largest amount. They could even offer to come play a game against another NFL team on the local football field, and sign autographs after.
Where will these actions be taken?
How much will emissions be reduced or sequestered vs. business as usual levels?
It depends on how motivated, and inspired, people are--and how much they feel that everyone around them is contributing (making them a slacker if they don't contribute themselves).
What are other key benefits?
Team spirit, comradrie, not killing the Earth, and NFL player autographs.
What are the proposal’s costs?
Depends. If it's put on by state and local governments, it would be pricy. If it's put on by the NFL, they might see it as a publicity stunt, and a way to get even more people (especially kids) interested in football.