Climate is still variable. El Nino, PDO, NAO, QBO -- it's not static and it's not linear.
What we have to worry about is the landlocked ice - most especially the West Antartica Ice Sheet. But this is not even close to melting, so this rising oceans scare a bunch of bunk.
James Hansen has stated several times that the "dangerous anthropogenic influence" would lead to ice sheet collapse. He's the one saying that it is necessary to start acting within the next decade to attempt to prevent something that could happen a century or more from now. Most people would admit that an ice sheet collapse wouldn't be a good thing.
If you recall, it was absolutely "proven" that CFCs would cause dramatic climate change.
I don't recall that the danger from CFCs and ozone depletion was expressed as a climate-change problem. My sense is that it was expressed as an environmentally-damaging problem.
You might keep in mind that an honest assessment of any climate model predicting the future is to see how well it predicts the past. So far, no climate model has a very good track record in this regard.
When this topic has been raised, I have referred to a discussion of the subject, which is below. You can evaluate it at your convenience; I can't add significantly to it.
http://mustelid.blogspot.com/2005/09/junkscience-is-junk.html
But even given that, is global warming necessarily bad? I know the assumption is, but just a few degrees change increases the crop land available.
It really depends on the rate of warming; ecosystems only adapt slowly. A perfect example is how treelines move in response to warming or cooling. Trees don't walk up or down mountains; if climate changes such that the habitable zone of a given species changes altitude, trees that fall out of the habitable zone will die, and new trees in the new habitable zone range will have to take root and grow. Some trees grow fairly fast, other's don't.
The problem with the discussion in the link you gave is it fails to mention the parameters that can be arbitrarily adjusted to produce results that match the climate record. They mostly repeat your "best tool we have" argument. As I showed in post 444, there are parameterizations that can be adjusted to produce any result particularly over a short time span such as a century. The dissenters in your link almost got it when they pointed out that the 20th century can be modelled with a 3 or 4 parameters in an algebraic equation. But that misses the precise point that the parameters used in the models are not verified or verifiable in reality except in a few limited and insufficient cases.