Global Warming Debate part 1

One of my friends has pasted a video claiming that global warming is a hoax. This sparked off a debate between us. Though there are several people who replied, I will just paste the debate I had with him, in four parts: His arguments in maroon and mine in blue .

K: Raju, What do you think of this video? I am surprised to hear what they are saying.
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Check out this video on YouTube.

Me: This is what I think:

K: That's disappointing. I thought you would say something rational, like evidence-based, scientific research based idea. Is there really any evidence that CO2 increases temperature in the atmosphere? It seems like the converse is true according to what environmentalists are saying. And I looked at the graph of sun radiation vs global temperature change graph which pretty much follows it.

Me: I wasn't sure whether you sent that video as a joke or not. But it appears that you didn't.

The overwhelming majority of climate scientists and experts are convinced that global warming is happening and is caused by human activity. Since you and I are not experts in this, the best thing to do (if you believe in the scientific method) is to trust them. Regarding your argument about solar radiation: If it is true do you think so many scientists from across the continents would have overlooked such an obvious explanation ?

Also I have seen several documentaries that give ample evidence for global warming. I am also not sure if solar radiation has been consistently increasing in the last 40 years. In fact I have read that the radiation reaching earth's surface has been reducing (until recently) due to air-borne pollutants. (This is called Global Dimming. It seems that global dimming has partially masked the effects of global warming i.e. without global dimming global warming would be happening even more rapidly.)

This discussion reminds me of the following. Consider the following sets of people.
1. Creationists (or people who don't believe in evolution).
2. Holocaust Deniers.
3. Global Warming Deniers.
4. 9/11 Debunkers.
5. Moon landing Deniers.

I conjecture that if a person falls in one of the above categories then there is a very good chance that they may fall in other categories as well ;) Do you agree ?