A balanced view on fracking?

Michael Bloomberg, the former mayor of New York City, and the President of the Environmental Defense Fund, have a more or less pro-fracking piece in today's NYT. They acknowledge some problems but argue that they are solvable, and that on balance natural gas is a step in the right direction. This seems a pretty common-sensical position, which in today's world probably means that no one will support it at all, alas....