In your opinion, does man-made global warming exist or do the natural processes of the Earth contribute more? And what makes you believe that?
Climate change is a better phrase than global warming. Yes, natural processes on the Earth (and in the sun or in space) contribute significantly to climate change. And yes, I think humanity is contributing to the current change in climate.
The reason, mainly, is the rate at which the climate is changing. The rate at which icesheets are melting. It is happening much more quickly than can be attributed to natural causes alone.
I guess part of that belief comes from listening to other scientists working in related fields and seeing movies of glaciers melting.
Of course, a second question then becomes what to do about it. The climate has changed considerably in the past. There is a mass extinction, life on Earth recovers and the cycle continues. It will be no different this time, if it gets that far. The question (for our sake) is whether we'll be among the species to go extinct if it should come to that.
Part of the problem in presenting a field like this to the general public is, first of all, the data is often scarce (because we've only been recording directly for so long) or indirect (tree rings, ice cores, each of which requires intermediate steps to interpret what they say about the climate). Year-to-year variations are huge (larger than any systematic trend, which only shows up in 5-year averages). The general public doesn't "get" a difficult concept like "rate of change", they like to hear "the temperature will increase by so-and-so much", and when they hear that the temperature will increase "so many degrees" they think "well, that's not too bad" because you get larger variations during a single day. People think that a few hundred years (not even a geological blink of an eye) is a long time. There's the climate models, which are still somewhat crude and imprecise and therefore not always reliable. And finally there's the fact that weather systems are chaotic systems and it's hard (not to say impossible) to predict what a small change today will do for the climate on a longer timescale (note the need to upscale "weather" to "climate", which is again not trivial).
Usually it's easier to predict the climate than the weather because the climate is less chaotic, but it is chaotic on some level (non-chaotic systems are never stable because they can't damp out small perturbations) and pushing it out of quasi-equilibrium too hard will trigger a phase where the climate changes rapidly and significantly before stabilising again.
People will tend to rely on our technology and innovation to counter any problems that may arise. But there are things our technology will be powerless to prevent. Natural disasters is an obvious example and I suspect climate change is another. Of course, people argue over whether that just reflects our current technology or whether at some point we'll have technology that will help (I think we won't ever have the kind of technology that can protect us from everything). Even if we did though, it's not obvious what the long-term effect of using such technology would be.
That's before you factor in political pressure that tries to confuse the issue one way or the other.
It is very hard to prove that the world is getting warmer when the average temperature is not raising.
Were that the case then yes, you'd have a point.
You know, sometimes I'd wish we could split the world up. Let the nay-sayers do to their part whatever the hell they like and let those of us who are a bit more responsible do unto their part what they want, then compare in a few hundred, a few thousand years. See who's laughing then. Unfortunately, we have to share the same world and choices made by a small group of people affect us all.
Though this might have to do with global warming. Maybe the warmer climate puts more water in rotation, which can be seen in more snow falling. Winter is still winter, even if the global temperatures rise.
The efficiency of the Gulf-stream is what matters. I don't know what the leading cause for the current winter is (it may be as simple as a year-to-year fluctuation), but if global temperatures rise the efficiency of the Gulf-stream decreases and Northern Europe gets colder (it'll get more similar to the climate on the other side of the Atlantic). Anyway, as I said, "global warming" is a confusing term.