Carbon dioxide has been the focus of a lot of discussions on global climate change and energy policy. Certainly, there are other greenhouse gases, but CO2 is the major by-product of our fossil-fueled economy that people have been massively pumping into the air at an extraordinary rate. Over millennia, biology has already come up with an answer to this problem -- in nature, carbon dioxide is part of a carbon cycle that is recycled and/or sequestered into wood or sugars or other forms of chemical storage. Perhaps some clever chemists/scientists can come up with another kind of photosynthesis to save us from dangerously high levels of carbon dioxide in the atmosphere? Check out some of these research projects that could turn CO2 into fuels.
If you'd like to read more awesome and interesting stuff, check out this unrelated (but not entirely random!) Techdirt post