Just because RE<C stopped in 2011 does not mean the RE world has not progressed since. Google has a history of stopping great projects such as their RSS feed Reader (which gave rise to even better products such as InoReader). RE<C was mostly a research facility building prototypes, they never went into the industrial stage. Current solar panels from the existing industry are already cheaper than coal, so that "Renewable Energy < cost of Coal" motto is already a reality for many states and countries. Since this year, there are already solar power plants that sell electricity to utilities at a price inferior to coal electricity, and we're only going to see more of them going forward.
And sorry to say, but combining one 2008 Hansen study with one 2011 Google study does make this exactly what the article says it isn't, a theoretical exercise based on stats analysis. I'd much prefer to go with the IPCC 2013 report for a broader picture. Their point of view also seem very limited to technology, with mentions such as "truly disruptive technologies are what our planet needs. To reverse climate change, our society requires something beyond today’s renewable energy technologies." We do have zero-carbon technologies already, some cheap, some more expensive, we just don't use them, or barely, so it seems to me that the most important factor is a change in society, how and what we consume energy, food, etc., and also a strong political determination by ourselves and our leaders to encourage the adoption of existing technologies and the research of new or improved ones. I don't dream about "disruptive" or revolutionary new technologies. If we find them, all the better, but there's work enough to implement what we have.
There are also other considerations that could use a bit of the same creativity that these two engineers say we should apply to such issues. For instance, when they say that agriculture will keep using fossil fuel, that's only because of a lack of such creativity. Farmers are not in the field with tractors every day, mostly during planting and combining and a few times in between, or to dry grain, that's when they use the most fuel. But there's plenty enough used oil coming from the fast food restaurants that could be used to make biodiesel to cover all agricultural needs and then some. There's also biomethane digesters deployed more and more at cow farms. Governments could encourage cover crops used to bury carbon and build humus by making the seeds cheap enough so that it becomes a mainstream practice wherever applicable. Eventually, we'll need to move toward systematic irrigation and drainage to control water usage and reduce cultivated acreage because of the corresponding higher yield. We'll need much more water, and also ways to bring it into drylands such as the Midwest, because while corn and soybean yields are high in the U.S., they rank around number 50 worldwide for dryland crops such as wheat. This is a total waste of resources, especially in drought years. We just can't allow weather to dictate how much food we get anymore, every grain planted counts.
And as far as society is concerned, since a lot of crops are grown as animal feed rather than human food, a small reduction of 10% of the Western World's meat consumption would have a tremendous impact on carbon. I am sure there are hundreds of other ideas that may even cost nothing to implement that could be part of a global strategy to reduce greenhouse gas emissions. I don't believe however that a technology could suck up existing carbon dioxide from the atmosphere, we'll probably need to work with forestry and agriculture with regular plants for that. Even if they can help, no need to wait for bio or other technologies for that. But yeah, it is clear that GHG in the atmosphere will not go down quickly but in the matter of several decades, between the long life cycle of carbon and the increased release of methane because of higher temperatures. Maybe we need to sequester more carbon with carbon fiber in our cars and buildings, and carbon nanotube batteries to store solar energy!