Reducing emissions is a fools game so far as being a response to climate forcing. They can't be reduced enough to matter without better technologies and decades of deployment, and if the models are right (unlikely) a great deal of change is already in the works with existing concentrations. That only leaves removal.

"The climate problem is too big to solve easily with the tools we have . . . David Keith and his team have developed a number of innovative ways to achieve the efficient capture of atmospheric carbon" . . .

Keith and his team showed they could capture CO2 directly from the air with less than 100 kilowatt-hours of electricity per tonne of carbon dioxide. Their custom-built tower was able to capture the equivalent of about 20 tonnes per year of CO2 on a single square metre of scrubbing material – the average amount of emissions that one person produces each year in the North American-wide economy.

"This means that if you used electricity from a coal-fired power plant, for every unit of electricity you used to operate the capture machine, you'd be capturing 10 times as much CO2 as the power plant emitted making that much electricity," Keith says.

The U of C team has devised a new way to apply a chemical process derived from the pulp and paper industry cut the energy cost of air capture in half, and has filed two provisional patents on their end-to-end air capture system.

The technology is still in its early stage, Keith stresses. "It now looks like we could capture CO2 from the air with an energy demand comparable to that needed for CO2 capture from conventional power plants, although costs will certainly be higher and there are many pitfalls along the path to commercialization."

Nevertheless, the relatively simple, reliable and scalable technology that Keith and his team developed opens the door to building a commercial-scale plant.

Richard Branson, head of Virgin Group, has offered a $25-million prize for anyone who can devise a system to remove the equivalent of one billion tons of carbon dioxide or more every year from the atmosphere for at least a decade.

If the electricity source produced no carbon emissions the net benefits would be even higher.

But what do they do with the captured CO2? In what form is it captured? That's one of the issues that makes char so appealing to me. It captures carbon, not carbon dioxide, and does so in a form that is durable and useful.