Al Gore appears to have adopted some language from a piece by Gwyn Prins and Steve Rayner titled The Wrong Trousers. For an long article on biochar (itslef interesting) in today’s FT:

Even if biochar does not fulfil all of the potential claimed for it, it could still make an important contribution. Al Gore, the former US vice-president and environmental campaigner, likes to point out that the search for a “silver bullet” to solve the problem of climate change has been a distraction. Instead, he argues, though there may be no silver bullet, “there is silver buckshot”. Only by bringing many different methods of cutting emissions or absorbing carbon to bear can we reduce atmospheric levels of carbon to within the limits of safety.

Biochar is another form of air capture of carbon dioxide. The Wrong Trousers by Prins/Rayner was published just over a year and can be found here.