Mike Hulme in WSJ.

Science never writes closed textbooks. It does not offer us a holy scripture, infallible and complete. This is especially the case with the science of climate, a complex system of enormous scale, at every turn influenced by human contingencies. Yes, science has clearly revealed that humans are influencing global climate and will continue to do so, but we don't know the full scale of the risks involved, nor how rapidly they will evolve, nor indeed—with clear insight—the relative roles of all the forcing agents involved at different scales.