For example, I read that actually Europe will start to get colder and colder.
That's still climate change though, isn't it?
The "clever" thing is that the nay-sayers have gained a foot-hold by constantly talking about the changes as "warming", not just "climate change", which could be either hotter or colder - then point at places which are, as you say, colder, as if the temperature in the main population centres is the be-all and end-all of it all.
The science has always said that the warming being talked about is an increase in average global temperature, but the effects will be most noticeable in the desert regions (which are already very hot), and (possibly more importantly) in the seas.
Changes to the ice-caps and the sea-temperature have always pointed to regions such as northern Europe getting colder; the Gulf Stream (warm water from the tropics which is channeled through the Atlantic to round Britain and onward) is being diverted, for example, so Britain will get colder on average, because of prolonged winters. It doesn't mean it won't be warm or warmer in summer, but the average over the year will be colder.
Whether or not the main cause is man-made or not (and the fact that the grounding of all 'planes over America for even a few days was accompanied by a recordable difference to temperature, suggests that man-made emissions do have a measurable effect), I'm not sure why there should be an argument against decreasing activities which are possibly harmful - it's not like we can go somewhere else if we do get it wrong, is it, so why gamble?
I see it being like you bailing out your basement if it has flooded: you have a gallon bucket, and you are throwing water out.
I have a thimble, and am throwing water in.
Even if what I am doing has a negligible effect on what you are doing, as long as I am doing it, it is worse for you: it will prevent you getting your basement dry, and I will be wasting water (and the money it is costing me to buy it).
If I stop doing it, it will make a difference to you, your basement, and I won't have to pay for water to throw into your basement - everybody wins!