He says the issue is unresolved, and is not supported one way or the other. The same view held by Dr. Judith Curry and many others.Funny thing is nowhere in that op-ed does he forward an alternate theory or even deny the impact of CO2. All he does is criticizes the IPCC and the 'alarmists'.
And let's not forget Zeke Hausfather from the Yale forum on climate change and the media:
http://www.yaleclimatemediaforum.org/2013/09/examining-the-recent-slow-down-in-global-warming/As with many things in science, there is still significant uncertainty surrounding climate sensitivity, and different approaches can obtain fairly different results. However, the longer the current slow-down continues, the more questions will arise about whether GCMs are getting either multi-decadal variability or climate sensitivity wrong.
What is clear is that there is still much we don’t understand about the many different factors impacting Earth’s climate system, especially over periods as short as a decade.