So if a large proportion of these climate scientists don't think that doubling the atmospheric CO2 concentration will cause problematic warming what (according to them) is causing the current problematic warming trend?
Do you understand the logical fallacy of "loaded question?" Look it up, because your question commits that fallacy.
Most scientists accept that there's been some warming. How much of it is caused by CO2 is an open question, because the models need adjusting (though to be fair, the main difficulty is likely in over-estimating feedbacks). Scientists disagree on that problem, but the main question that matters from a practical standpoint is, "what should we do?" There's no consensus on this at all.
1) Should we do nothing, because eventually technology will replace coal before anything bad happens? (this is suggested by John Christy).
2) Should we do nothing, even though damage will be caused, because the damage will be easier to fix than to prevent? (I believe Bjorn Lomborg holds this view).
3) Should we replace all coal plants with nuclear immediately, even at great expense? (this is proposed by James Hansen)
4) Should we spend a lot of money on research for fusion?
5) Should we spend a lot of money to help push forward the electric car? (I saw this proposed in the Wall Street Journal)?
6) Should we replace all coal power with wind and solar? (this isn't actually possible with today's technology, but some people want it)
7) Should we agree to the Kyoto protocol, damaging the economy while making little impact on CO2 release?
8) Should we agree to the Copenhagen accord, which will do little, but cost billions in transfer payments to impoverished countries?
This is just scratching the surface of possible responses, and there is absolutely no scientific consensus on how to respond to AGW, or even if it needs a response.