The only realistic way to reduce CO2 emissions is by developing much more efficient and much cheaper solar technology. If it's cheaper than coal/gas/oil/nuclear and can be relied upon under any weather conditions, then businesses, governments, and consumers will use it. This could happen with better solar cells, and with better large-capacity batteries that charge much faster and hold a charge longer without losing efficiency over time. The production of those batteries would also have to be less harmful to the environment than current battery technology as well. With the number of people working on solving these problems, the solutions seem likely to occur within the next hundred years, or sooner. Global warming is probably not going to eradicate all human life in the interim.
Another possibility is in gathering excess CO2 from our atmosphere, or before it gets to our atmosphere, and launching it beyond Earth's atmosphere into space. If we can control how much CO2 gets trapped in our atmosphere, then we could theoretically pump out as much of it as we want without causing further warming. The first person to solve that problem is going to become very wealthy, especially since it's a solution that big energy companies are likely to favour. However, there may be other unforeseen consequences to removing so much carbon from the Earth, never to return. Hopefully any such consequences would be less catastrophic than the end result of global warming.
