For global warming alarmists to be correct about what we need to do, all
of the following must be true.
1. The globe is warming.
2. The warming is caused by us.
3. There are not sufficient negative feedbacks to halt it.
4. The net effect is bad.
5. The proposed solution is better than leaving the status quo in place.
It's not dishonest to note problems with all of those points, even if for the sake of discussion you occasionally stipulate one of the other points as true. Each has problems. Note that I'm not claiming the skeptics are right on every point, only that it's not dishonest of them to note problems with each of the above steps.
1. Seems to be at a standstill. It appeared to be waming before, but almost all of the warming (USHCN at least, haven't double checked GHCN) was present in the adjustments not the raw data. Those adjustments can be questioned. My personal suspicion is that the mathematical model they use to adjust for Time of Observation bias magnifies the existing data. It's not a good sign that the successive iterations have had the warming in adjustments go up, while the rate of warming in raw data hasn't shifted significantly. Compare USHCNv2 to v3 sometime. If those adjustments need to be made according to the physics, than that's fine, but it still qualifies as deeply suspicious, and was a legitimate point of contention.
2. Really hard to establish, since we know non human variation has included periods of much greater and lower warmth and CO2 concentrations. Even establishing climate sensitivity is iffy, and the number has changed several times over the past couple of decades. Protestations to the contrary, the form of the equation they use for climate sensitivity is not
3. Again, hard to establish. They net direction of water vapor isn't known for certain since more vapor -> more clouds, and clouds are cooling agents. It might not even be unidrectional. It could act as warming at some points, cooling at others. Gotta love chaotic systems. The recent unpredicted pause is evidence that there are negative feedbacks which have not been handled correctly or not included at all.
4. Well, take a look at the warmlist sometime and see if you can understand why this claim is not trusted. Almost all claims on this point don't even acknowledge the possible positive effects of warming. http://wattsupwiththat.com/2010/01/06/winter-kills-excess-deaths-in-the-winter-months/
is one example argument that warmer temps cause fewer deaths.
5. Lots of arguments can be found about adaptation being more effective than cutting CO2 emissions. Certainly more politically achievable in many countries. YMMV.